Estimation of economic and hydrologic impacts of water management policies in the Yellowstone River Basin by Derrell Sylvester Peel A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Applied Economics Montana State University © Copyright by Derrell Sylvester Peel (1982) Abstract: A partitioned linear programming model of the Yellowstone River Basin is developed. The model maximizes returns over variable costs to a vector of alternative irrigated agricultural crops. Demands for water in municipal use, energy production and minimum instream flows are included in the model as model constraints. With the basic model as a benchmark, a number of scenarios reflecting alternative water management policies and changes in important variables are evaluated. Specific scenarios include increased levels of irrigation efficiency, increased irrigated acreage in the basin, below average levels of river flow which would be associated with dry years and increased, levels of prices for agricultural products. The results of the basic model indicate the presence of time and site specific water scarcities which are exaggerated in the scenarios of increased agricultural prices or below average flows. The results also indicate that water management policies designed to increase the level of irrigation water use efficiency will, within some range, result in increases in returns over variable costs to irrigated agricultural production. However, the costs of increasing irrigation efficiency are not calculated in the model. Model results indicate that increasing irrigation efficiency may result in significant income redistribution, between sectors within the basin. ESTIMATION OF ECONOMIC AND HYDROLOGIC IMPACTS OF WATER MANAGEMENT POLICIES IN THE YELLOWSTONE RIVER BASIN by D e rre ll S y lv e ster Peel A t h e s i s subm itted in p a r t i a l f u l f il l m e n t of th e re q u ir e m e n ts f o r th e degree of Master of S cien ce in A p p l i e d Economics MONTANA STATE UNIVERSITY Bozeman, Montana December 1982 MAIN U 8. hi [SYS ii Cbp- APPROVAL o f a t h e s i s s u b m i t t e d by D e rre ll S y lv e ste r Peel T h i s t h e s i s h a s b e e n r e a d by e a c h member o f t h e t h e s i s c o m m i t t e e and h a s b e en f o u n d t o be s a t i s f a c t o r y r e g a r d i n g c o n te n t, E n g lish usage, fo rm at, c i t a t i o n s , b ib lio g r a p h ic s t y l e , and c o n s i s t e n c y , and i s r e a d y f o r s u b m i s s i o n t o t h e C ollege of G raduate S tu d ie s . ,,/ D ate C h a i r p e r s o n , G r a d u a t e Committe e Z7 Approved t h e Major D e p a r t m e n t , 19 8 Head, Major D e p a r t m e n t D ate A p proved f o r / L- D ate Z— G r a d u a t e Dean iii STATEMENT OF PERMISSION TO USE In p r e s e n tin g t h i s t h e s i s in p a r t i a l f u l f i l l m e n t of th e r e q u i r e m e n t s f o r a m a s t e r ' s d e g r e e a t Montana S t a t e U n i v e r ­ sity , I a g r e e t h a t t h e L i b r a r y s h a l l make i t a v a i l a b l e t o borrow ers under r u l e s of th e L ib ra ry . B r i e f q u o t a t i o n s fro m t h i s t h e s is are allow able w ith o u t s p e c ia l perm issio n , pro ­ v i d e d t h a t a c c u r a t e acknowledgement o f s o u rc e i s made. P e r m i s s i o n f o r e x t e n s i v e q u o t a t i o n fro m o r r e p r o d u c t i o n o f t h i s t h e s i s may b e g r a n t e d by my m a j o r p r o f e s s o r , o r i n h i s / h e r a b s e n c e , by t h e D i r e c t o r o f L i b r a r i e s , when, i n t h e opinion of e i t h e r , th e proposed use of th e m a te r ia l i s fo r sch o larly purposes. Any c o p y i n g o r u s e o f t h e m a t e r i a l i n t h i s t h e s i s f o r f i n a n c i a l g a in s h a l l n o t be allo w ed w ith o u t my w r i t t e n p e r m i s s i o n . S ignature D a t e ____ ^ \ sZJLX __________________ iv V ita D e r r e l l S y l v e s t e r P e e l was b o r n J u l y 3 0 , 1959 i n Mul eshoe^ T e x a s , He i s t h e f o u r t h c h i l d o f M, A, raJ a c k ra and D e a l i a P e e l , D e r r e l l and h i s f a m i l y moved t o P a b l o , Montana i n 1964, He g r a d u a t e d f r o m Ronan High S c h o o l i n 1977 and e n t e r e d Montana S t a t e U n i v e r s i t y t h a t f a l l . A fter he g r a d u a t e d w i t h a B,S, i n Farm and Ranch Management i n t h e s p r i n g , he b e g an w o rk on an M.S, d e g r e e i n A p p l i e d E c o n o m ic s i n t h e f a l l o f 1981, V Acknowledgm ents I w o u l d l i k e t o e x p r e s s my s i n c e r e t h a n k s a n d a p p r e c i a t i o n t o my g r a d u a t e c o m m i t t e e : D r e R o b e r t. T a y l o r , Dre B r u c e B e a t t i e , and D r e R i c h a r d B r u s t k e r n f o r t h e i r g u i d a n c e and a d v i c e . . I e s p c e c i a l l y w i s h t o t h a n k my g r a d u a t e c h a i r m a n ^ Dre R i c h a r d McConnen f o r h i s w i s e c o u n s e l and n e v e r - e n d i n g f l o w o f i d e a s . In a d d it i o n , I w o u l d l i k e t o t h a n k Mike N i c k l i n and Ted W i l l i a m s i n t h e C i v i l E n g i n e e r i n g d e p a r t m e n t and P h i l F a m e s o f t h e Montana s t a t e o f f i c e o f SCS-USDA f o r t h e i r a d v i c e w i t h t e c h n i c a l hydrologic m atters. S i n c e r e a p p r e c i a t i o n i s e x t e n d e d t o my m o t h e r and my f a m i l y f o r t h e i r c o n t i n u e d s u p p o r t t h r o u g h o u t my a c a d e m i c career. L astly, t o my w i f e , P a t , I w a n t t o e x p r e s s my d e e p e st g r a t i t u d e f o r both her d e d ic a te d a s s i s t a n c e w ith t h e p r e p a r a t i o n o f t h i s t h e s i s and h e r c o n t i n u e d s u p p o r t and p a t i e n c e t h r o u g h many l o n g d a y s and n i g h t s . vi TABLE OF CONTENTS Page Chapter L i s t o f T a b l e s * o****************************** i L l S t Of FiyUiTOS o o e e e e o e o e e e e c e o e e o e e e o e o o e e o o e AbSt ITS Ct e e e e e e e e f f e e e e e o e e e o o o o e o e e o e e e e e o e e o e e INTRODUCTION xx Xl Xll 9-e> e e o o e e e e o e o o e e e e e e e e e e e o o e o e e e e e e S c l C l C Q ST O U n C l e e o e e e e o o e e e o e o e o e o o e o e o o e e o e o o e e o e 2 L O C fclI 6 I S S U 0 S © o © o o e o © o o o © ® © o o o o 9 o o o © © o o 6 o o © o o © S t 0 t 0 W d .t 0 IC L a w o e © o e e e o o » e o © e » o e o © © ® ® e © 9 » o Fo cl ©ifo I I y R o s o r v o d Watosr o © © * ® © ® ® © ® ® ® ® © © © ® ® The Y e l l o w s t o n e R i v e r Compact©®®©®©®©®©®®® The W ater Problem®o©©®®®©®®©®©®©®©©©©®©©®©©©© P o s s i b l e S o l u t i o n s ®a©®©©©®©*©©*®®©©®©©©©©©* ©© ^ i r r i g a t i o n and R e t u r n Flows® ee®©©®®©©®©®®©®©© W ater Quality©©oo©©©®®®©©©©©®©©©©©©®©©®®©©©©© O b ^ e c t i v e s 0 0 ©©©©©©©©©©®®®®©©©©®©®®©®®®®°®®°°® -ECONOMIC AND HYDROLOGIC THEORY0 o o e e e e e o o o o o o e a o o H y d r o l o g i c Theorye®©©©®©®©©®®©®©®©®©©©©®®®®©® RunOffoo©®©©©©®©©©©©©©®©®®©®©©©®®®®®®©©0®® Hydrographs© ©o©©©©©©®©.©©©*©®®©*®®®®®*®®®®® S t r e a m f l o w and I r r i g a t i o n © * ©©©©®©o®©©©©©©®®®© Economic Theorye©©©©©©©©©©©©©®®©©©©©©©®©®®®®® H e n e f i t / C o s t Fr a mewor le©®©©©©©©©©©®©©©©©©©® An A l t e r n a t i v e M e t h o d o l o g i c a l A p p r o a c h , THE MODEL® ©e 6 8 9 10 12 14 15 17 19 19 22 25 25 32 32 41 o o e ® e o © e © e o o e © o ® ® o ® ® o © ® ® ® © ® ® © ® ® ° ® The S t a n d a r d L i n e a r Programming P r o b l e m , S p a t x a l Dxmensxon 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 * 0 0 0 @0 0 0 Time Di me n s i o n * o***************************** The Hydro l o g x o Model * * * * * * * * * * * * * * * * * * * * * * * @ 0 The I r r i g a t e d A g r i c u l t u r e Mo d e l «*«*. **»**»*** The O b ] e c t x v e Functxon* e********************* The B a s x n wWxde Model ******** * **************oo R e s e r v o x r s *e ********************************* l e e e e o e 47 52 53 56 59 60 63 v ii TABLE OF CONTENTS--Continued C hapter Page DATA SOURCES AND PREPARATION e 66 o o e o o e o e e o o o o o o e o e o Th© BaSlC Mod ©I eooooooooeooooooooooooooooooe H y d r o l o g i c D a t al e o o o e o o Q o e e o e e o e o e e o e o e o o o e o e e Conve yanc e and F i e l d E f f i c i e n c i e s R e tU rn Flows »ooe ooe e ooe QO- - ' ~~" ~~ Minimum Flow R e q u i r e m e n t s ' o o o e o o o o o o o o o o e o o o e e M u n i c i p a l and E n e r g y R e l a t e d W ater Use I r r i g a t e d Acres® oo@ooo@oe*®o*@*@o@oo0 o@o*@o® I r r i g a t e d Crops® ®®e®oo®@@®®®®®®® ®o®®®®®®®®®® R e t u r n s Over V a r i a b l e C o s t (ROVC)®®®®» ®. ®®. ® S u g a r B e e t and Bean A c r e a g e R e s t r i c t i o n s ® ®®® Net I r r i g a t i o n R e q u i r e m e n t s ® .......... ......................... A l t e r n a t i v e Scenarios®®®®®®*®®®®®*®®®®®®®®®®® ^ In creased I r r i g a t i o n E ffic ie n cy Scenarios Dry Year S c e n a r i o s ® o ® ® ® ® * ® ® ® ® ® ® ® ® ® ® ® ® ® ® ® ® I n c r e a s e d L e v e l o f A g r i c u l t u r a l P r i c e s ® ®® I n c r e a s e d I r r i g a t e d Acreage S c e n a r io s ^ 0 4 9 0 0 0 9 0 0 0 0 9 * 0 0 0 0 9 0 0 0 0 0 0 0 0 0 0 9 0 0 0 9 0 0 0 0 0 0 9 0 0 0 0 0 0 *0 RESULTS. 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9 0 9 0 0 0 0 0 9 0 C a l i b r a t i n g t h e Model R e s u l t s o f t h e B a s i c Model.® ,R e su lts of In c re a s e d I r r i g a t i o n E f f i c ie n c y Scenarios® H y d ro lo g ic Im pacts Economic I m p a c t s R e s u l t s o f t h e Dry Year S c e n a r i o s ® R e s u l t s of th e I n c r e a s e d I r r i g a t e d Acreage S c e n a r i o s ® o®®®®®®®®®®®®®®®®*®®®®®*®®®®®®®® R e su lts of the In creased A g ric u ltu ra l P ric e s Scenarios®.e®®®®®®®®*®®®®*®®®®®®®*®®®®®®®® C a v e a t s and L i m i t a t i o n s o f t h i s Study®.®*®®® S u g g e s t e d R e f i n e m e n t s o f t h e Mode l ®. . ®. ®. 0 0 0 0 0 0 9 0 9 0 0 0 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9 0 0 0 0 0 0 0 0 0 0 0 9 0 0 0 0 0 0 0 0 0 0 0 0 6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9 0 0 0 9 0 0 0 9 0 9 0 0 0 0 0 0 0 0 9 0 9 6 9 9 0 0 0 0 9 0 0 0 9 0 6 . 66 67 68 70 72 73 73 74 77 77 78 78 78 79 81 82 83 85 88 96 96 97 98 99 100 100 102 CONCLUSIONS, POLICY IMPLICATIONS AND SUGGESTIONS FOR FURTHER RESEARCH® * ® ® o * ® ® ® e ® @ o ® o ® ® ® ® ® ® * ® ® ® ® 104 C o n c l u s i o n s and P o l i c y I mpl i cat i ons . ®®®®®. ®®. S u g g e s t i o n s f o r F u r t h e r Research®. ®®. ®. ®®®®®. 104 112 v iii TABLE OF CONTENTS--Continued Page Chapter APPENDICESe e e e o e e e e o e e o e e e o A p p e n d l X A® e o o e o o e o o e o 0 0 0 0 0 © 0 0 ® 0 0 0 0 0 ©© 0 0 p® 0 0 © 115 e o o o e e o e o o a a o o o a o o o o o o 116 125 127 o o o e e o o o o o o a o o o o o o o e o o o 136 o o © o © o o o o © e o o o o © o a © o o © o A p p e n d ix Bo®®®®®®®®®®* A p p e n d ix C®e®®*®*®®®®® o 0 » 9 O e O 0 O © © O O O O O © G O 9 O © O O REFERENCES CITED....................... ix LIST OF TABLES Table 1. Page The N in e S u b - b a s i n s o f t h e Y e l l o w s t o n e R i v e r and A sso c ia ted H ydrologic D r a i n a g e s . , o . , , 49 C u r r e n t and F u t u r e L e v e l s o f Conveyance and F i e l d E f f i c i e n c i e s ®. . © . ©. o o o c o o o o e o o o o o o . o o . o o . 69 3. R e t u r n Flow P a t t e r n Used i n t h e LP M o d e l . . . . . . . . . 71 4. Minimum I n s t r earn F l o ws o . . . . . . . . . . . . . . . . . . . . . . . . . 72 5. I r r i g a t e d A c r e a g e s o f t h e N in e S u b - b a s i n s u s e d i n t h e LP Model . o©. ©. ©©©. ©©. ©©©. . . . ©. ©. . ©. ©©©® 75 6. A l t e r n a t i v e C r o p s f o r t h e N in e S u b - b a s i n s . . . . . . . 76 7. B a s i n - w i d e Summary o f t h e B a s i c Model ( B I ) . . . . . . 89 8. T o t a l D i v e r s i o n s and R e t u r n F l o w s . . © . © . . . . . . . . . © 90 9. D i v e r s i o n s by Sub—b a s i n . © © . . . © © © . . . . . . . © o © . © . . . . 90 10• R e t u r n Flows by Sub—b a s i n . . . . . . a . © © . © . © © . © . . . © . © 91 11. B asin -w id e Cropping P t . 92 12. Ret u r n s t o Ag r i c u l t u r e©. . ©. . . . ©. ©. ©©©. ©. ©. ©. ©©©© 93 13. Shadow P r i c e s o f Wat er©©©. ©o©. . ©©. . . -. . ©©©. . ©. ©©© 94 14. Shadow P r i c e s o f I r r i g a t e d A c r e a g e . © . . . . . . . . . . . . 95 15. Irrig a te d A lfalfa for Sub-basins I , 2, 16 . Irrig a te d A lfalfa for S u b - b a s i n s 5 and 7 . . . . . . . . 118 17. Irrig a te d A lfalfa for S u b -b a sin s 6, 8 , and 9 . . . . 119 18. I r r i g a t e d Corn f o r G r a i n f o r A l l S u b -b asin s..... 120 19. I r r i g a t e d Feed B a r l e y f o r A l l S u b - b a s i n s . . . . . . . . 121 20 . I r r i g a t e d B e an s f o r A l l Sub—b a s i n s . . . . . . . . . . . . . . 122 2. a t e r n s . 3 , and 4© 117 X LIST OF TABLES— C o n t i n u e d Table Page 21« I r r i g a t e d Sugar B e e ts f o r A ll S u b - b a s i n s . . 0 22. I r r i g a t e d Corn S i l a g e f o r A l l S u b - b a s i n s 0 0 0 9 0 0 124 23. C l i m a t i c Zones f o r t h e Nine S u b - b a s i n s 0 0 0 0 0 0 126 24. Ne t I r r i g a t i o n R e q u i r e m e n t s . . . . . . . . . . . . . . . . . . . . . 126 25. C r o p p i n g P a t t e r n s by S u b - b a s i n f o r t h e B a s i c Model (BI) and t h e P l and P2 S c e n a r i o s . . . . . . . . 128 C r o p p i n g P a t t e r n s by S u b - b a s i n f o r t h e El Scenario. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 C r o p p i n g P a t t e r n s by S u b - b a s i n f o r t h e E2 and E3 Scenarios. . . . . @. . . . 130 C r o p p i n g P a t t e r n s by S u b - b a s i n f o r t h e Dl S c e n ario *. . . . . . . . . . . . . o . . . . . . . . . . . . . . . o . . . . . . . . 131 26. 27. 28. 29. 30. 31. 32. 9 0 0 0 0 0 C r o p p i n g P a t t e r n s by S u b - b a s i n f o r t h e D2 S c e n a r i o . . . . . . . . 0 9 0 0 0 . . 123 132 C r o p p i n g P a t t e r n s by S u b - b a s i n f o r t h e Al Scenario.. . . . . . . o . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 C r o p p i n g P a t t e r n s by S u b - b a s i n f o r t h e A2 Scenario.. . . . . . . . . . O . . . . . . . . . . . . . . . . . . . . . . . . . . 134 C r o p p i n g P a t t e r n s by S u b - b a s i n f o r t h e A3 Scenario.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 xi LIST OF FIGURES Figure Page 1. S i m p l i f i e d Diagram o f t h e H y d r o l o g i c a l C y c l e . . , . 21 2. D iagram m atic R e p r e s e n t a t i o n of th e Runoff P r o c e s s . . . . =. . . . . < . » » 0 . . . . . . 23 A v e r a g e M o n th ly Flow o f t h e Y e l l o w s t o n e R i v e r a t S i d n e y , M ontana, f o r W ater Y e a r s 1 9 3 4 - 1 9 8 0 . 26 4. Components o f W ater L o s s fro m I r r i g a t i o n S y s t e m s 29 5. C o n c e p t u a l D iagra m o f t h e I r r i g a t i o n R e t u r n Flow S y s t e m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 M a r g i n a l B e n e f i t s (MBw) and M a r g i n a l C o s t s (MCw) o f W ater U s e . . . . . . . . . . . . . . . . . . . . . . . . . ®• ®. . . . . ® 34 M a r g i n a l B e n e f i t s and M a r g i n a l C o s t s o f I r r i g a t i o n E f f i c i e n c y (E1 ) . . . . . . . . . . . . . . . . . . . . . 38 P u b l i c and P r i v a t e M a r g i n a l B e n e f i t s and M a r g i n a l C o s t s o f I r r i g a t i o n E f f i c i e n c y (E1 ) . . . 40 The Nine P l a n n i n g S u b - b a s i n s of t h e Y e l l o w s t o n e R i v e r B a s i n . . . . .......... .. 48 10 . The N in e S u b - b a s i n s a s a Ne t wo r k . . . . . . . . . . . . . . . . 50 11. The Nine S u b - b a s i n s S u b m a t r i c e s i n t h e P a r t i t i o n e d L i n e a r Programming Fram ew o rk . . . . . . . 51 Flow C h a r t o f t h e P r i n c i p a l Components o f t h e LP Mo d e l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 "Movement63 o f W ater f ro m t h e R i v e r t o C r o p s i n t h e LP Mo d e l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 "Movement" o f I n s t r e a m Flow from an U p s t r e a m S u b - b a s i n t o an I m m e d i a t e l y Downstream S u b - b a s i n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ®. . . ®. SI S i m u l a t i o n o f R e s e r v o i r i n t h e LP Mo d e l . . . . . . . . . 65 3. 6. 7. 8. 9. 12. 13. 14. 15. x ii A bstract A p a r t i t i o n e d l i n e a r p r o g r a m m i n g model o f t h e Y ellow stone R iver B asin i s developed. The model m a x i m i z e s r e t u r n s over v a r i a b l e c o s t s t o a v e c to r of a l t e r n a t i v e i r r i g a t e d a g r i c u l t u r a l crops. Demands f o r w a t e r i n m u n i c i ­ p a l u s e , e n e r g y p r o d u c t i o n and minimum i n s t r e a m f l o w s a r e i n c l u d e d i n t h e model a s model c o n s t r a i n t s . W ith t h e b a s i c m odel a s a b e n c h m a rk , a number o f s c e n a r i o s r e f l e c t i n g a l t e r n a t i v e w a t e r m an agem en t p o l i c i e s and c h a n g e s i n i m p o r t a n t v a r i a b l e s a r e e v a l u a t e d . S p ecific sc e n a rio s include in cre ased l e v e ls of i r r i g a t i o n e f f i c ­ i e n c y , i n c r e a s e d i r r i g a t e d a c r e a g e i n t h e b a s i n , be lo w a v e r a g e l e v e l s o f r i v e r f l o w w h i c h w o u ld be a s s o c i a t e d w i t h d r y y e a r s and i n c r e a s e d , l e v e l s o f p r i c e s f o r a g r i c u l t u r a l products. The r e s u l t s o f t h e b a s i c m o d e l i n d i c a t e t h e p r e s e n c e o f t i m e and s i t e s p e c i f i c w a t e r s c a r c i t i e s w h i c h a r e e x a g ­ g e ra te d in th e s c e n a rio s of in c re a s e d a g r i c u l t u r a l p r ic e s o r b e lo w a v e r a g e f l o w s . The r e s u l t s a l s o i n d i c a t e t h a t w a t e r m anagem ent p o l i c i e s d e s i g n e d t o i n c r e a s e t h e l e v e l o f i r r i g a t i o n w a t e r u s e e f f i c i e n c y w i l l , w i t h i n some r a n g e , r e s u l t in i n c r e a s e s in r e t u r n s over v a r i a b l e c o s t s to i r r i g a t e d a g r i c u l t u r a l production. However, t h e c o s t s o f in c re a s in g i r r i g a t i o n e f f ic ie n c y a re not c a lc u la te d in the m o d e l. Model r e s u l t s i n d i c a t e t h a t i n c r e a s i n g i r r i g a t i o n e f f i c i e n c y may r e s u l t i n s i g n i f i c a n t income r e d i s t r i b u t i o n , betw een s e c t o r s w i t h i n th e b a s in . I Chapter I In troduction I s s u e s r e g a r d i n g w a t e r r e s o u r c e s have r e c e i v e d much a t t e n t i o n in the U nited S ta te s in re c e n t y e a rs. Increasing s c a r c i t y o f w a t e r due t o i n c r e a s i n g demands a n d / o r d e c r e a s ­ i n g q u a l i t y h a s i n c r e a s e d t h e c o n f l i c t s among w a t e r u s e r s , e n v i r o n m e n t a l c o n c e r n s and w a t e r f o r e n e r g y , a g r i c u l t u r a l , m u n i c i p a l and o t h e r i n d u s t r i a l u s e s . T his problem i s p a r t i c u l a r l y a c u t e i n many a r e a s o f t h e W e s t e r n U n i t e d S t a t e s where a h i s t o r y of p u r e , a b u n d a n t w a t e r s u p p l i e s and a m y r i a d o f w a t e r r e l a t e d l a w s and l e g a l i s s u e s , often c o n f u s i n g and c o n f l i c t i n g a n d , i n many c a s e s , j u d i c i a l l y te s te d for the f i r s t tim e o n ly r e c e n t l y , have combined t o b r i n g w a t e r p o l i c y c o n s i d e r a t i o n s t o t h e f o r e f r o n t of p ublic attention. I n a 1960 p u b l i c a t i o n , H i r s h l e i f e r , DeHaven, and M illim an c o r r e c t l y noted t h a t w ater r e l a t e d i s s u e s are o f t e n a p p r o a c h e d w i t h more e m o t i o n t h a n c l e a r t h i n k i n g . They s t a t e : Much n o n s e n s e h a s b e en w r i t t e n on t h e u n i q u e im p o rtan c e of w a t e r su p p ly to th e n a tio n , or to p a r tic u la r regions. G r a n t e d t h a t t h e n a t i o n , or any i n d i v i d u a l t h e r e o f , c o u l d n o t s u r v i v e w i t h o u t w a t e r , t h a t d o e s n o t show u n i q u e n e s s . No human can s u r v i v e w i t h o u t fo o d , w i t h o u t oxygen, and w i t h o u t a v a r i e t y o f o t h e r s u p p o r t i n g 2 e n v i r o n m e n t a l c o n d i t i o n s many n o t ev en f u l l y . k n o w n t o d a y (p .4 ). However, t h i s d o e s n o t i m p l y t h a t w a t e r r e s o u r c e s a r e . undeserving of s c i e n t i f i c in q u iry . W h il e no m ore a ’’n e c e s ­ s i t y " t h a n many o t h e r g o o d s , w a t e r r e s o u r c e s a r e p l a g u e d w i t h a c e r t a i n u n i q u e n e s s due t o t h e many c o m p e t i n g and o v erlapping uses of w ater, th e e x t e r n a l i t i e s a sso c ia te d w ith w ater use, th e absence of m arkets to a l l o c a t e w ater in many c a s e s , and t h e h a z y n a t u r e o f w a t e r o w n e r s h i p and u se r i g h t s d u e t o t h e s p a t i a l and i n t e r t e m p o r a l c o m p l e x i t i e s o f h y d ro lo g ic system s. T h u s, a s c o n c e r n and a t t e n t i o n t o t h e s e i s s u e s i n c r e a s e s and s o l u t i o n s become i m p e r a t i v e , much i n f o r m a t i o n w i l l be r e q u i r e d f o r s o c i e t y t o a r r i v e a t s a t i s f a c t o r y so lu tio n s. Issu es regarding w ater reso u rces are in v a ria b ly u n i q u e t o a s p e c i f i c l o c a l i t y and c o m p l e t e s o l u t i o n s w i l l involve s i t e s p e c i f i c study. A ccordingly t h i s study i s c o n c e n t r a t e d on s p e c i f i c r i v e r m an ag em en t a l t e r n a t i v e s i n t h e Y e l l o w s t o n e R i v e r B a s i n i n Montana. How ever, i t i s hoped t h a t t h e methods used i n t h i s stu d y w i l l p r o v id e i n s i g h t s i n t o w a t e r m an ag em en t i s s u e s t h a t w i l l a p p l y t o o th er a re a s as w e ll. B a ck g ro u n d The Y e l l o w s t o n e R i v e r , a t r i b u t a r y o f t h e M i s s o u r i R i v e r , h a s i t s h e a d w a t e r s i n n o r t h w e s t e r n Wyoming, t h e s i t e o f Y e l l o w s t o n e N a t i o n a l P a r k , and f l o w s i n a g e n e r a l l y 3 n o r t h e a s t e r l y d i r e c t i o n a c r o s s s o u t h e a s t e r n Montana and a s m a l l p o r t i o n o f N o r t h D a k o ta t o i t s c o n f l u e n c e w i t h t h e M issouri River, F r e e - f l o w i n g f o r t h e f u l l 670 m i l e r e a c h o f t h e m a i n s t e m , t h e Y e l l o w s t o n e s u p p o r t s some o f t h e f i n e s t s p o r t f i s h e r i e s in th e U nited S t a te s , Some 550 m i l e s o f t h e m a i n s t e m a r e l o c a t e d i n Montana. The m a j o r t r i b u t a r i e s o f t h e Y e l l o w s t o n e : t h e C l a r k s Fo rk o f t h e Y ellow stone? t h e B ig h o r n ? t h e Tongue? and t h e Powder r i v e r s l i k e w i s e h a v e t h e i r h e a d w a t e r s i n Wyoming and f l o w n o r t h ­ w a r d i n t o Montana b e f o r e j o i n i n g t h e Y e l l o w s t o n e . Thus? over o n e -h a lf of th e w a ter sup p ly of th e Y ello w sto n e River i s p r o d u c e d i n Wyoming. The Y e l l o w s t o n e R i v e r B a s i n i n Montana? w i t h w h i c h t h i s s t u d y i s c o n c e r n e d ? d r a i n s a b o u t 35?000 s q u a r e m i l e s w h ic h is roughly h a l f of th e t o t a l d ra in a g e of th e b a s in . The b a s i n i s g e o g r a p h i c a l l y a l a n d o f e x t r e m e s r a n g i n g fro m t h e snow -capped peaks o f t h e w e s t e r n p o r tio n ? where t h e Y ellow ­ s t o n e R i v e r e n t e r s Mon tana f r o m Y e l l o w s t o n e Park? t o t h e r o l li n g p la in s of the e a s te rn p o rtio n . E le v a t i o n s range fro m o v e r 12?000 f e e t i n t h e m o u n t a i n s t o a b o u t 2?000 f e e t w h e r e t h e r i v e r l e a v e s Montana. The c l i m a t e o f t h e b a s i n d i s p l a y s v a r i a t i o n t o match t h e geography. Average annual p r e c i p i t a t i o n r a n g e s f r o m a b o u t 6.6 i n c h e s i n p a r t o f C a rb o n County? t h e d r i e s t p o r t i o n o f t h e b a s i n ? t o 24 i n c h e s i n P a r k County? w h i c h h a s t h e h i g h e s t a v e r a g e a n n u a l p r e c i p it a ti o n in the basin. Average t e m p e r a t u r e s range 4 f r o m 15,2 d e g r e e s f a r e n h e i t i n t h e w i n t e r t o 75 d e g r e e s f a r e n h e i t i n t h e summer. The b a s i n t h u s m a i n t a i n s a v a s t number o f d i f f e r e n t m i c r o c l i m a t e s and s u p p o r t s a w i d e v a r i e t y o f f l o r a and f a u n a . The p r i m a r y s o u r c e o f w a t e r f o r t h e Y e l l o w s t o n e r i v e r i s sn ow pack t h a t a c c u m u l a t e s i n t h e m o u n t a i n s o f t h e h e a d ­ w aters. Average an n u al flow o f th e Y e llo w sto n e R iver a t S i d n e y , M o n ta n a , f o r t h e y e a r s 1 9 34-1980 i s 8.9 mmaf ( m i l l i o n a c r e - f e e t ) w i t h a v a r i a t i o n o f f l o w s f r o m 4.2 mmaf t o 15.4 mmaf.1 S n o w m e lt r u n o f f i n t h e b a s i n u s u a l l y b e g i n s a b o u t A p r i l and r e a c h e s a p e ak i n May and J u n e . A v e rag e m o n t h l y f l o w s t h r o u g h o u t t h e y e a r w i l l r a n g e f ro m l e s s t h a n .4 mmaf t o a b o u t 2 mmaf a t S i d n e y w i t h t h e l o w f l o w s , o c c u r r i n g i n t h e l a t e summer and f a l l . The b a s i n i s a s p a r s e l y p o p u l a t e d r e g i o n c o v e r i n g some f o u r t e e n c o u n t i e s i n t h e s o u t h c e n t r a l and s o u t h e a s t e r n p a r t of th e s t a t e . B illin g s, in Y ellow stone county, i s th e l a r g e s t c i t y in the b asin. T h e r e a r e tw o I n d i a n r e s e r v a ­ t i o n s i n t h e Y e l l o w s t o n e B a s i n ; t h e Crow R e s e r v a t i o n , 1 1The u s e o f a v e r a g e s can be v e r y m i s l e a d i n g . Average flow s of th e Y ellow stone a re e x tre m e ly s e n s i t i v e to the t i m e p e r i o d upon w h i c h t h e y a r e b a s e d . For e x a m p l e , a v e ra g e a n n u a l f l o w s a t Sidney f o r th e 5 y e a r p e r io d 19341 9 3 8 w e r e 6 .7 mmaf a n d f o r t h e 5 y e a r p e r i o d 1 9 7 4 - 1 9 7 8 w e r e 10.6 mmaf. I n a d d i t i o n , some a u t h o r s p r e f e r t o a d j u s t t h e raw h i s t o r i c a l a v e r a g e t o r e f l e c t a p a r t i c u l a r l e v e l o f developm ent. The DNRC (1 977a, pg. 17) r e p o r t a v e r a g e f l o w s a t S i d n e y o f 8.8 mmaf w h e n a d j u s t e d t o t h e 1 9 7 0 l e v e l o f . d e v e l o p m e n t , and B o r i s and K r y t i l l a (1980, pg, 62) r e p o r t f l o w s o f 8 . 4 5 mmaf w h e n a d j u s t e d f o r t h e 1975 l e v e l o f developm ent. 5 l o c a t e d i n B i g h o r n and Y e l l o w s t o n e c o u n t i e s , and t h e Nor­ t h e r n Cheyenne r e s e r v a t i o n , im m ediately a d ja c e n t to the Crow r e s e r v a t i o n t o t h e e a s t i n B i g h o r n and Rose bud co u n ties. A g r ic u ltu r e , i s t h e most im p o r ta n t i n d u s t r y in the b asin. A p p r o x i m a t e l y 570,000 o f t h e n e a r l y 2 5 ,0 0 0 ,0 0 0 a c r e s in th e b a s in a re p r e s e n t l y under i r r i g a t i o n . 2 D e p a r t m e n t o f N a t u r a l R e s o u r c e s and C o n s e r v a t i o n The (DNRC) (1977b) p r o j e c t s a maximum i n c r e a s e i n e c o n o m i c a l l y f e a s i ­ b l e i r r i g a t e d a c r e a g e o f a b o u t 2 3 7 ,0 0 0 a c r e s . Irrig ated a g r i c u l t u r e i s by f a r t h e m a j o r u s e r o f w a t e r i n t h e Y ellow stone B asin w ith v i r t u a l l y a l l i r r i g a t i o n w ater c o m in g f r o m s u r f a c e s u p p l i e s . P r e s e n t consum ptive use of w a t e r f o r i r r i g a t i o n i s a b o u t 1.1 m m a f / y . 3 The o t h e r m a j o r p r i m a r y i n d u s t r y i n t h e b a s i n i s c o a l m ining. C u r r e n t l y c o a l m ining ra n k s f a r behind a g r i c u l t u r e i n e c o n o m i c i m p o r t a n c e b u t h a s t h e p o t e n t i a l t o become a very s i g n i f ic a n t in d u s try .4 I n 1977, some 29.3 m i l l i o n t o n s o f c o a l w e r e r e p o r t e d m in e d i n t h e b a s i n , rep resenting a b o u t a 3 0 - f o l d i n c r e a s e o v e r m i n i n g 10 y e a r s p r e v i o u s l y . T h e r e a r e a n e s t i m a t e d 50 b i l l i o n t o n s o f c o a l r e s e r v e s i n 2 T hes e a r e f u l l y i r r i g a t e d a c r e s a s r e p o r t e d by t h e SCS (1978, T a b l e I l i a ) , and do n o t i n c l u d e w a t e r s p r e a d i n g acreage. 3 The 1.1 mmaf was r e p o r t e d by t h e SCS-USDA (1978, pg. 24). The DNRC (19 7 7 a, pg. 33) r e p o r t s i r r i g a t e d a g r i c u l t u r a l c o n s u m p t i v e u s e a s 1 . 5 mmaf. 4See DNRC (1977d, p p . 1 1 -36) f o r e n e r g y r e l a t e d developm ent p r o j e c t i o n s . 6 e a s t e r n M ontana, w h i c h a r e p r e s e n t l y e c o n o m i c a l l y f e a s i b l e t o m i n e , i n d i c a t i n g t h a t t h e c o a l i n d u s t r y h a s much room t o grow. C o a l m i n i n g by i t s e l f u s e s a l m o s t no w a t e r . 5 In a d d i t i o n , c u r r e n t l e v e l s o f i n s t a t e e n e r g y p r o d u c t i o n from coal i s a lso a r e l a t i v e l y i n s i g n i f i c a n t w ater user. How­ e v e r , d e p e n d i n g on t h e f o rm o f t e c h n o l o g y a p p l i e d , e n e r g y p ro d u c tio n in th e f u t u r e could r e p r e s e n t a s i g n i f i c a n t demand f o r w a t e r ( B o r i s and K r u t i l l a , pp. 1 0 4 - 1 3 0 ) . The s i t u a t i o n a p p e a rs p a r t i c u l a r l y a c u t e g iv en t h a t t h e bulk of M o n t a n a 's c o a l r e s e r v e s a r e l o c a t e d i n t h e r e l a t i v e l y w a t e r s c a r c e Tongue and Powder s u b - b a s i n s . L ikew ise, c u rr e n t w a t e r de mands f o r m u n i c i p a l and o t h e r i n d u s t r i a l u s e s a r e in sig n ifican t rela tiv e to a g r i c u l t u r a l uses. Legal Issu e s O w n e r s h i p o f M o n t a n a 's w a t e r r e s o u r c e s i s a l a b y r i n t h of ta n g le d le g a l is s u e s a t the s t a t e , federal in te rstate , and lev els.5 S t a t e W ater Law A ll w a t e r i n t h e s t a t e i s d e c l a r e d t o be p u b l i c p r o p e r t y by t h e s t a t e l e g i s l a t u r e a l t h o u g h t h i s i s c l o u d e d by l a r g e l y u n s p e c i f i e d f e d e r a l c l a i m s ( d i s c u s s e d l a t e r i n 5See B o r i s and K r u t i l l a (1980, pp. 9 4 -104) f o r a d e s c r i p ­ t i o n o f t h e c o a l m i n i n g p r o c e s s and r e l a t e d w a t e r u s e . 5A good d e s c r i p t i o n o f w a t e r r e l a t e d l a w s and l e g a l i s s u e s c a n b e f o u n d i n B o r i s a n d K r u t i l l a ( 1 9 8 0 , c h . 2 & 3) and DNRC (19 7 7 n , p p . 4 5 - 5 4 ) . 7 t h i s chapter) However, estab lish (M o n t. Code A n n o t . , 1 9 7 9 , 8 5 - 2 - 1 0 1 , s e c t . I ) . s t a t e l a w a l l o w s i n d i v i d u a l s and e n t i t i e s t o t h e r i g h t t o d i v e r t and u se w a t e r i n t h e s t a t e . W a t e r u s e r i g h t s a r e b a s e d on t h e d o c t r i n e o f p r i o r a p p r o ­ p riatio n . T his d o c tr in e , a d o p t e d i n Montana i n 18 6 5 , e s s e n t i a l l y s t a t e s t h a t r i g h t s to use w a te r a re c h ro n o lo g i­ c a l l y o r d e r e d , w ith t h e o l d e s t r i g h t s having t h e h i g h e s t p r i o r i t y , i.e ., " f i r s t in tim e , f i r s t in rig h t". Use r i g h t s under p r i o r a p p r o p r i a t i o n a r e a l s o s u b j e c t to a number o f o t h e r c o n d i t i o n s , t h e p r i m a r y one b e i n g t h a t t h e w a t e r be p u t t o " b e n e f i c i a l u s e " , (Mont. Code A n n o t . , 1979, a s d e f i n e d by t h e s t a t e 85-2-102, sect. 2). The p r o c e s s by w h i c h w a t e r r i g h t s a r e e s t a b l i s h e d h a s gone t h r o u g h some m o d if ic a tio n s over tim e. Many o f t h e e a r l y w a t e r r i g h t s w e r e e s t a b l i s h e d s i m p l y by p u t t i n g t h e w a t e r t o u s e (Bowman and L e s s l e y , p. 4 ). I n many c a s e s t h e r e was no r e c o r d of d a t e or q u a n t i t y o f w a t e r a s s o c i a t e d w i t h t h e s e r i g h t s . L a t e r o n , r i g h t s w e r e e s t a b l i s h e d by p o s t i n g n o t i c e o f i n t e n t t o d i v e r t w a t e r and f i l i n g t h e n o t i c e w i t h t h e c o u n t y c l e r k and r e c o r d e r T hes e use r i g h t s , (Bowman and L e s s l e y , p. 4). accum ulated over the y e a rs , a re often c o n f u s i n g and o v e r l a p p i n g . The Montana W a t e r Use A ct o f 1973 s e t i n m o t i o n a s t a t e - w i d e p e r m i t s y s t e m f o r use r i g h t s and m a n d a t e d a c o m p l e t e a d j u d i c a t i o n o f e x i s t i n g w ater rig h ts (Mont. Code A n n o t . , 1979, 8 5 - 2 , p a r t 2). 8 The a d j u d i c a t i o n p r o c e s s r e q u i r e s t h a t h o l d e r s o f w a t e r r i g h t s p r i o r t o J u l y I , 1973 f i l e n o t i c e o f s u c h r i g h t s w i t h t h e DNRC s o t h a t a l l r i g h t s e x i s t i n g a s o f t h a t d a t e c a n be e v a l u a t e d and q u a n t i f i e d s i m u l t a n e o u s l y by a c o u rt proceeding. From t h a t p o i n t on, new r i g h t s w i l l be i s s u e d by t h e DNRC, and a l l a p p l i c a t i o n s w i l l be h a n d l e d by th at agency. The W a t e r Use A c t o f 1973 a l s o r e c o g n i z e d a n d g r a n t e d l e g a l s t a n d i n g f o r i n s t r e a m u s e s o f w a t e r and i n i t i a t e d t h e p r o c e s s whereby governm ent a g e n c ie s , but n o t i n d i v i d u a l s , could apply f o r r e s e r v a t i o n of w a te r fo r p r e s e n t or f u t u r e b e n e f i c i a l use. T h ese r e s e r v a t i o n s c o u l d a p p l y t o b o t h i n s t r e a m and w i t h d r a w a l u s e . F e d e r a l l y R e s e r v e d W ater F u rth er co m p lica tin g th e le g a l s ta tu s of w ater reso u r­ ces i s th e e x i s t e n c e of u n s p e c i f i e d q u a n t i t i e s of w a te r r e s e r v e d f o r t h e Crow and N o r t h e r n Cheyenne I n d i a n r e s e r v a ­ tions, T h e s e r e s e r v e d w a t e r s , h i n g e d on t h e W i n t e r s D o c trin e of 1908, e s s e n t i a l l y g u a r a n te e a d e q u a te w a te r to m e e t t h e f u t u r e demands o f t h e r e s e r v a t i o n , w h a t e v e r t h a t f u t u r e demand may be. T his p la c e s p o t e n t i a l l y l a r g e de mands on t h e w a t e r o f t h e Y e l l o w s t o n e R i v e r and s p e c i f i ­ c a l l y on t h e B i g h o r n and Tongue s u b - b a s i n s . The Wind R i v e r I n d i a n R e s e r v a t i o n i n N o r t h e r n Wyoming a l s o h a s p o t e n t i a l i m p a c t s on t h e i n f l o w o f t h e B i g h o r n R i v e r i n t o Montana i n th is regard. 9 O t h e r f e d e r a l e s t a b l i s h m e n t s i n t h e b a s i n , s u c h as m ilita r y re s e rv a tio n s , n a tio n al f o r e s ts , w ilderness areas, et cetera, a re su b je c t to w ater r e s e r v a tio n s in a s im ila r manner. The Y e l l o w s t o n e R i v e r Compact The f i n a l c o m p l i c a t i n g l e g a l a r e a w i t h r e g a r d t o t h e Y ellow stone B asin i s i n t e r s t a t e P rim arily, com petition fo r w ater. t h e i s s u e i s t h a t o f d e c i d i n g how t h e w a t e r o f t h e Y e l l o w s t o n e and i t s t r i b u t a r i e s s h o u l d be d i v i d e d b e t w e e n Montana and Wyoming. T h is i s s u e i s embodied in t h e Y e l l o w s t o n e R i v e r Compact (Mont. Code A n n o t . , 1979, 85-20). The c o m p a c t , r a t i f i e d by C o n g r e s s i n 19 5 1 , i s b e t w e e n t h e tw o s t a t e s , b u t a l s o i n c l u d e d N o r t h D a k o ta a s a s i g n a t o r y s t a t e s i n c e t h e a c t i o n s of t h e o t h e r two s t a t e s d i r e c t l y a f f e c t w a te r a v a i l a b l e i n North Dakota. The c o m p a c t , and t h e c o m m i s s i o n s e t up t o a d m i n i s t e r i t , has th e s e prim ary featu res: first, to recognize a p p ro p ria tiv e r i g h ts to b e n e f i c i a l u se s o f w a te r in each s i g n a t o r y s t a t e a s of January I , 1950? s e c o n d , t o s p e c i f y t h e s h a r e s o f u n a p p r o ­ p r i a t e d w a t e r i n t h e t r i b u t a r i e s t o be a l l o c a t e d t o Montana and Wyoming? t h i r d , t o g i v e e a c h s i g n a t o r y s t a t e v e t o power over t r a n s f e r s of w ater out of th e b a sin . Two c o n s e q u e n c e s a r e i m p o r t a n t r e g a r d i n g t h e Y e l l o w s t o n e Compact. F irst, to d a t e , th e d i v i s i o n of u n a p p r o p r i a t e d w a t e r b e t w e e n Montana and Wyoming a s s p e c i ­ f i e d i n t h e compact has n o t been a p p l i e d , bu t i t a p p e a rs 10 t h a t t h e t i m e i s r a p i d l y a p p r o a c h i n g when s u c h a p p l i c a t i o n w i l l be n e c e s s a r y . S e c o n d l y , t h e Compact h a s no i m p a c t on, or le g a l sta n d in g w ith , the w a te rs re se rv e d fo r th e Indian R e se rv a tio n s in th e b a sin , th e r e f o r e th e a b i l i t y of the Compact t o r e s o l v e i n t e r s t a t e w a t e r i s s u e s i s h i n d e r e d . The W ater Pro b lem The q u e s t i o n o f t h e a d e q u a c y o f w a t e r i n t h e Y e l l o w ­ s t o n e B a s i n t o m e e t c u r r e n t and f u t u r e dem ands i s n o t an e a s y one. The a d j u d i c a t i o n o f c u r r e n t w a t e r . r i g h t s i n t h e b a s i n i s u n d e r way b u t may t a k e a s l o n g a s 1 5 - 2 0 y e a r s t o com plete.^ T h i s makes r e s o l u t i o n o f new a p p l i c a t i o n s f o r r i g h t s very d i f f i c u l t in th e in te rim . Thu s, t h e e x i s t e n c e o f c o n f l i c t s b e t w e e n p r e s e n t u s e s , new u s e s and w a t e r re s e r v e d f o r f u t u r e use i s u n c le a r . I t is clear, however, t h a t t h e q u e s t i o n o f a d e q u a c y m u s t be a n s w e r e d i n t h e c o n t e x t o f f l o w s a t s p e c i f i c l o c a t i o n s and p o i n t s i n t i m e . T h e r e a r e t w o t i m e d i m e n s i o n s t o be d i s t i n g u i s h e d , t e m p o r a l v ariatio n s, i.e., v a r i a t i o n i n f l o w fr o m y e a r t o y e a r , intertem poral v a ria tio n s , the year. Water s h o r t a g e s , i.e., and v a r i a t i o n in flow w ith in to the e x te n t th a t they e x is t o r w i l l d e v e l o p , a r e t i m e and s i t e s p e c i f i c . W h i l e i t may be t r u e t h a t t h e r e i s enough w a t e r in t h e b a s i n t o m eet ^ P r e l i m i n a r y r e s u l t s w i l l be a v a i l a b l e i n t h e i m m e d i a t e f u t u r e b u t f i n a l l e g a l d e c r e e s may be many y e a r s h e n c e . ( T e l e p h o n e c o n v e r s a t i o n w i t h Mike McLane, A d j u d i c a t i o n P r o g r a m M a n ag e r, DNRC, S e p t e m b e r 1 3 , 1982). . 11 demands i n t o t a l , basin th a t, i t i s tr u e t h a t th e re a re a re a s in the a t c e r t a i n tim es during th e y ear, p re s e n tly appear to experience sh o rtag es of w ater. In th e p l a i n s re g io n , c r i t i c a l l y low f l o w s , approach™ i n g no f l o w s i n some s t r e a m s , o c c a s i o n a l l y o c c u r i n t h e f a l l c a u s in g s e r i o u s w a te r a v a i l a b i l i t y problem s fo r both irrig ato rs and f i s h a nd w i l d l i f e (DNRC 1977a, p. 17). As demands f o r w a t e r grow t h e s e s i t u a t i o n s w i l l w o r s e n . I n t h e e a r l y 70®s , a b o u t t h e t i m e t h a t t h e Montana W a t e r Use Act was p a s s e d , c o al developm ent in th e b a sin began gro w in g a t a r a p i d r a t e . T h i s r e s u l t e d i n a wave o f c o n s t e r n a t i o n r e g a r d i n g w a t e r r e s o u r c e s i n t h e b a s i n and was t h e s o u r c e o f much r e s e a r c h t o i d e n t i f y p o s s i b l e s o l u t i o n s t o c o n f l i c t s among c o m p e t i n g w a t e r u s e r s . o f t h e r e s e a r c h was c a r r i e d on by t h e DNRC.® years, Much In re c e n t t h e r a t e o f c o a l d e v e l o p m e n t h a s s l o w e d and w h i l e th e p a n i c - o r i e n t e d c o n ce rn s i n i t i a l l y e x p re s s e d have no t m a t e r i a l i z e d , t h e r e i s every i n d i c a t i o n t h a t coal develop­ m e n t w i l l c o n t i n u e t o grow a s w i l l o t h e r i n d u s t r i a l and a g r ic u ltu r a l uses. T h u s, s o l u t i o n s t o t h e s e p r o b l e m s a r e as im p o rta n t as ev er. T h es e s o l u t i o n s m u st d e a l w i t h two c o m p o n e n t s ; t h e p h y s i c a l and h y d r o l o g i c a l c h a r a c t e r i s t i c s of the b a sin , ®Much Study, and a 1977a, i.e., when and w h e r e w a t e r i s a v a i l a b l e , o f t h i s work i s e m b o d ie d i n t h e Y e l l o w s t o n e I m p a c t a s e r i e s o f e l e v e n t e c h n i c a l r e p o r t s (DNRC, 1977d-n) f i n a l r e p o r t (DNRC, 1 9 8 1 ). See a l s o DNRC (1975, 1977b, 1 9 7 7 c ) . 12 and t h e l e g a l q u e s t i o n s o f t h e s i z e and p r i o r i t y o f r i g h t s t o use t h e , a t t i m e s , l i m i t e d s u p p l y o f w ater. P ossible Solutions What k i n d s o f s o l u t i o n s a r e a v a i l a b l e t o s o l v e t h e s e problem s? The DNRC r e c o g n i z e s t h r e e p o s s i b l e s o l u t i o n s ? w a t e r r e s e r v a t i o n s , a d d i t i o n a l s t o r a g e , and i m p r o v e d w a t e r management ( 1 9 7 7 a , p . 71). The u s e o f w a t e r r e s e r v a t i o n s , p r o v i d e d f o r i n t h e W a t e r Use A ct o f 1973, a l l o w s p u b l i c a g e n c i e s t o p r o v i d e f o r f u t u r e w a t e r demands a n d , i m p o r t a n t l y , r e c o g n i z e s and p r o t e c t s i n s t r e a m u s e s f o r f i s h an d w i l d l i f e , h e a l t h , and r e c r e a tio n a l purposes. W ater r e s e r v a t i o n s w e r e d e s i g n e d t o u n t a n g l e so m e o f t h e l e g a l h e a d a c h e s a n d t o p r o v i d e a f r a m e w o r k f o r a l l o c a t i n g w a t e r among a l t e r n a t i v e u s e s . I n c r e a s e d s t o r a g e c a p a c i t y p r o v i d e s a means o f s o l v i n g some o f t h e s p a t i a l and i n t e r t e m p o r a l w a t e r d i s t r i b u t i o n problem s. However, t h e . i s s u e o f i n c r e a s e d s t o r a g e c a p a c i t y r a i s e s much c o n c e r n o v e r who w i l l b u i l d , c o n t r o l , and a d m in iste r the f a c i l i t i e s , who w i l l g e t t o u s e t h e w a t e r and, p a r t i c u l a r l y , t h e p r e s e r v a t i o n o f f i s h e r i e s , h a b i t a t and l o w - l y i n g a g r i c u l t u r a l l a n d s . w ild life These i s s u e s make i t a p p e a r t h a t i n s t r e a m s t o r a g e f a c i l i t i e s a r e p o l i t i c a l l y i n f e a s i b l e in v i r t u a l l y a l l a re a s of the 13 b asin .9 T h i s r e q u i r e s t h e u s e o f more e x p e n s i v e o f f s t r e a m s to r a g e to im plem ent t h e s to r a g e a l t e r n a t i v e . I t would a p p e a r t h a t t h e r e is. enough d i s a g r e e m e n t and d i s c o n t e n t a b o u t i n c r e a s e d s t o r a g e t h a t i t w i l l n o t be a v i a b l e a l t e r n a t i v e to so lv e a l l of th e w a ter problem s in th e Y ellow stone Basin. The t h i r d a l t e r n a t i v e p r o p o s e s b e t t e r m an ag em en t o f w a ter being c u r r e n t l y used, p r i m a r il y fo r i r r i g a t i o n , to c o n s e r v e w a t e r and i n c r e a s e a v a i l a b i l i t y f o r o t h e r u s e s . C u r r e n tly , o v e r a l l i r r i g a t i o n e f f i c i e n c y in th e Y ellow stone R i v e r B a s i n i s a b o u t 19 p e r c e n t (SCS-USDA, 1978, T a b l e Ilia). In o th e r w ords, l e s s th an o n e - f i f t h of th e w ater d i v e r t e d f r o m t h e r i v e r i s u s e d c o n s u m p t i v e l y by a g r i c u l ­ t u r a l crops. T h e r e i s much c o n c e r n o v e r t h e o t h e r f o u r - f i f t h ' s t h a t i s taI o s t t5. I t w o u ld a p p e a r t h a t t h e r e i s i n d e e d some room f o r w a t e r c o n s e r v a t i o n t h r o u g h b e t t e r r i v e r m an a g em en t. I n c r e a s i n g t h e l e v e l of i r r i g a t i o n e f f i c i e n c y would red u c e t h e d i v e r s i o n r e q u i r e m e n t f o r i r r i ­ gation. However, t h e r e a r e some i m p l i c a t i o n s o f t h i s c o n s e r v a t i o n t h a t h a v e , a t l e a s t t o some e x t e n t , b e e n overlooked. T h i s s t u d y p r o p o s e s t o e x a m in e and d e v e l o p , in 9The A l l e n s p u r dam s i t e , one o f t h e more p r o m i s i n g r e s e r ­ v o i r s i t e s f r o m a r i v e r m an ag em en t s t a n d p o i n t , was t h e s u b j e c t o f a j o i n t r e s o l u t i o n o f t h e 1974 Montana L e g i s l a ­ t u r e a s b e i n g c o n t r a r y t o s t a t e g o a l s and o b j e c t i v e s (DNRC, 1975, pg. 2). _________________________ :______________________________________________________________________ 14 some d e t a i l , t h e s e i m p l i c a t i o n s , and e v a l u a t e t h e e c o n o m ic i m p a c t o f a l t e r n a t i v e r i v e r m anagem ent p o l i c i e s on t h e Y e l l o w s t o n e B a s i n and t h e s t a t e o f Montana, I r r i g a t i o n and R e t u r n Flows As s t a t e d p r e v i o u s l y , a p p r o x i m a t e l y 80 p e r c e n t o f t h e w a t e r d i v e r t e d f r o m t h e r i v e r i s l o s t fro m t h e i r r i g a t i o n s y s t e m b e f o r e b e i n g u s e d by a g r o n o m i c c r o p s . However, r o u g h l y 90 p e r c e n t o f t h a t t8I o s t ra w a t e r e v e n t u a l l y r e t u r n s to th e r i v e r as r e t u r n flows. The r e m a i n i n g w a t e r i s t r u l y " lo s t* t o t h e s u r f a c e flow system because i t e v a p o r a te s , p e r c o l a t e s i n t o deep groundw ater a q u i f e r s , e t cetera. The r e t u r n f l o w s e n t e r t h e r i v e r a f t e r some t i m e d e l a y and d o w n s t r e a m fr o m t h e o r i g i n a l d i v e r s i o n p o i n t . T h es e r e t u r n f l o w s , a l t h o u g h s u b t l e i n t h e i r i n t e r ­ a c tio n w ith th e h y d ro lo g ic system , a re n e v e r th e le s s a s i g n i f i c a n t f a c to r in th e flow of th e r i v e r . I t has long been rec o g n ize d t h a t w a te r r e e n t e r i n g th e r i v e r as r e tu r n f l o w s can be r e u s e d . in C a lifo rn ia , t h e same w a t e r , T e e l e , d e s c r i b i n g t h e S a n t a Ana R i v e r i n 1915, s t a t e s ? " I t i s thus e v id e n t t h a t in p a s s i n g from m ountain t o s e a , a distance o f n o t m o r e t h a n 100 m i l e s , may b e u s e d a t l e a s t e i g h t t i m e s f o r p ower and i r r i g a t i o n (pip. 2 3 - 2 4 ) S o i l C o n s e r ­ v a tio n S e rv ic e f i g u r e s in d ic a t e t h a t annual r e t u r n flow s in t h e Y e l l o w s t o n e a r e a b o u t 3.1 mmaf, o v e r o n e - t h i r d o f t h e av erag e an n u al flow of th e r i v e r as m easured a t Sidney (SCS-USDA, 1 9 78). 15 More i m p o r t a n t . a r e t h e i m p l i c a t i o n s f o r t h e d i s t r i b u ­ t i o n of w a ter flow thoughout th e y e a r. The m o s t c r i t i c a l p e rio d re g a rd in g w ater a v a i l a b i l i t y „ a t th e p r e s e n t tim e, a r e t h e m o n th s o f A u g u s t and S e p t e m b e r when r e l a t i v e l y lo w . r i v e r flow i s coupled w ith high d i v e r s i o n of w ater for irrig atio n . G iv e n t h a t r e t u r n f l o w s a r e d e l a y e d som ewhat a f t e r d i v e r s i o n , t h e b u l k o f w h i c h o c c u r s i n t h e May t o Septem ber i n t e r v a l , s i g n i f i c a n t p o r t i o n s of th e p r e s e n t l e v e l s o f l a t e summer f l o w of t h e r i v e r a r e due t o r e t u r n flow s. The DNRC ( 1 9 7 7 a ) , r e c o g n i z i n g t h e s i g n i f i c a n c e o f re tu rn flow s s t a t e , " I n many a r e a s w a t e r u s e r s h ave l e g a l r i g h t s t o w a t e r l o s t by i r r i g a t o r s a b o v e t h e m , and t h e i r r i g h t s c o u l d b e a d v e r s e l y , a f f e c t e d b y t h e u s e o f mo r e e fficien t irrig atio n p r a c t i c e s , (p. 72)". W ater Q u a l i t y The q u a l i t y o f r e t u r n f l o w w a t e r i s u s u a l l y l o w e r t h a n i t was b e f o r e d i v e r s i o n due t o t h e i n t r o d u c t i o n o f s a l t s , p e s t i c i d e s , s e d i m e n t a r y m a t e r i a l a n d / o r o r g a n i c m a t t e r . 1® I n some a r e a s o f i r r i g a t e d a g r i c u l t u r e i n t h e W e s t e r n U nited S t a t e s , th is q u a lity issue is c r i t i c a l . For e x a m p l e , p o r t i o n s o f t h e Upper Rio Grande V a l l e y and much o f t h e C o l o r a d o R i v e r B a s i n a r e c h a r a c t e r i z e d by s e v e r e s a l i n i t y p r o b l e m s and t h e q u a l i t y c o m p o n e n t o f t h e r e t u r n 10 1 0 See Boone (1976) and DNRC ( 1 9 7 7 f , pp. 7 7-80) f o r more d e t a i l e d d i s c u s s i o n s of w a te r q u a l i t y a s p e c ts of r e t u r n flow s. 16 flow i s s u e i s c r i t i c a l . The Y e l l o w s t o n e B a s i n i s somewhat u n i q u e i n t h i s r e s p e c t f o r tw o r e a s o n s . F irst, th e basin i s c h a r a c t e r i z e d by u n u s u a l l y h i g h q u a l i t y s u r f a c e w a t e r i n g e n e r a l , and s e c o n d , t h e r e i s a l a c k o f i n d i c a t i o n o f w idespread w ater q u a li t y d e g ra d a tio n throughout the basin. W h i l e c e r t a i n a r e a s o f t h e b a s i n may p r e s e n t p o t e n t i a l q u a l i t y problem s i t does n o t appear t h a t t r e a t i n g r e t u r n f l ows in t he e n t i r e b a sin as p r i m a r i l y a q u a l i t y is s u e is ap propriate. Fo r t h i s r e a s o n t h i s s t u d y w i l l n o t d e a l w i t h t h e q u a l i t y i s s u e and w i l l c o n c e n t r a t e i n s t e a d on t h e q u a n t i t y and d i s t r i b u t i o n a l c o m p o n e n ts o f w a t e r i n t h e Y ellow stone Basin. The c o n s e r v a t i o n o f w a t e r t h r o u g h b e t t e r r i v e t manage­ m en t a s a s o l u t i o n t o t h e w a t e r p r o b l e m i n t h e Y e l l o w s t o n e B a s i n h a s r e c i e v e d much a t t e n t i o n . T his i s u n d e rs ta n d a b le b e c a u s e i t a p p e a r s t o b e an o b v i o u s a l t e r n a t i v e . I t allow s c o n s e r v a t i o n o f w a t e r f o r a l t e r n a t i v e u s e s and s i m u l t a n e ­ o u sly c o n tr i b u te s to th e m aintenance of w ater q u a li t y . In a d d i t i o n , i t i s n o t p l a g u e d w i t h t h e l e g a l and p o l i t i c a l c o n t r o v e r s i e s s u r r o u n d i n g t h e . w a t e r r e s e r v a t i o n and s t o r a g e altern ativ es. I t appears t h a t th e re a re s i g n i f i c a n t u n d e sirab le e c o n o m ic i m p l i c a t i o n s o f p r o p o s e d r i v e r m an agem en t p o licies. S p e c i f i c a l l y , p o l i c i e s which a re d i r e c t e d to w a rd im proving th e o v e r a l l e f f i c i e n c y of w ater used f o r i r r i g a ­ t i o n may r e s u l t i n a r e d u c t i o n i n t h e q u a n t i t y o f r e t u r n 17 flow i n th e r i v e r , i.e., may c h a n g e t h e d i s t r i b u t i o n o f r i v e r flow throughout th e y ear. T h e r e f o r e , p o l i c i e s of i n c r e a s e d e f f i c i e n c y o f w a t e r u s e may a l t e r t h e a d e q u a c y o f t h e r i v e r t o m e e t w i t h d r a w a l and i n s t r e a m u s e s , even a t c u r r e n t e c o n o m i c l e v e l s and a v e r a g e r i v e r f l o w s . Increased e f f i c i e n c y p o l i c i e s a l s o have i m p l i c a t i o n s f o r o t h e r r i v e r m an a g em en t p o l i c i e s s u c h a s , i r r i g a t i o n p r o j e c t d e v e l o p m e n t and r e s e r v o i r c o n s t r u c t i o n . T h es e i m p l i c a t i o n s a r e even more e x a g g e r a t e d i n l i g h t o f o t h e r v a r i a b l e s s u c h as? v ariatio n in th e p h y s ic a l system , i.e., runoff, p re c ip ita ­ t i o n , e v a p o r a t i o n ? f u t u r e e c o n o m ic g r o w t h i n t h e b a s i n ? and o t h e r economic c o n d i t i o n s , ag ricu ltu ral i.e., l e v e l of p r i c e s fo r products. O bjectives The p u r p o s e o f t h i s s t u d y i s t o e x a m in e t h e e c o n o m ic i m p l i c a t i o n s o f c u r r e n t r i v e r m an ag em en t p o l i c i e s , Y ellow stone River B asin. in the T h i s w i l l be a c c o m p l i s h e d by com pleting th e fo llo w in g o b je c tiv e s : (1) D e v e l o p m e n t o f a model o f t h e Y e l l o w s t o n e R i v e r B a s i n , t h a t i n c o r p o r a t e s t h e a p p r o p r i a t e e c o n o m i c and h y d r o l o g i c t h e o r y and p o l i c y f a c t o r s t o e v a l u a t e c u r r e n t m an a g em en t p o l i c i e s . (2) E v a l u a t i o n of th e econom ic im p a c ts o f i n c r e a s e d e f f i c i e n c i e s o f w a t e r u s e by p a r a m e t r i c a l l y i n c r e a s i n g t h e l e v e l o f e f f i c i e n c y o f w a t e r u s e i n t h e m o d e l. 18 (3) E v a l u a t i o n o f c u r r e n t m an ag em en t p o l i c i e s i n l i g h t o f o t h e r p h y s i c a l and e c o n o m ic f a c t o r s , s u c h a s low er-than-average r iv e r flow s, a lte r n a tiv e p ric e le v e ls and f u t u r e a g r i c u l t u r a l d e v e l o p m e n t , and d i s c u s s i o n o f t h e s e i m p l i c a t i o n s i n r e l a t i o n t o o t h e r m an ag em en t a l t e r n a tiv es. 19 C hapter 2 Economic and H y d r o l o g i c T h eo ry The p u r p o s e s o f t h i s c h a p t e r a r e t o s e t f o r t h t h e h y d r o l o g i c and e c o n o m i c t h e o r y a p p r o p r i a t e t o an u n d e r ­ s t a n d i n g o f t h e s i t u a t i o n p r e s e n t e d i n C h a p t e r I and t o d i s c u s s . (I) t h e i m p l i c a t i o n s and l i m i t a t i o n s o f s u c h t h e o r y i n t h e l i g h t o f d a t a a v a i l a b i l i t y and o t h e r f a c t o r s and (2) t h e a d a p t a t i o n s n e c e s s a r y in o rd e r to use t h e t h e o r y to achieve q u a n t i f ic a t i o n of the s t a te d o b je c tiv e s . H y d ro lo g ic Theory An u n d e r s t a n d i n g o f t h e e c o n o m ic i m p a c t s o f a l t e r n a ­ t i v e r i v e r m an a g em en t p o l i c i e s r e q u i r e s a t l e a s t a c u r s o r y u n d e rstan d in g of th e h y d ro lo g ic p ro c e sse s involved. The h e a r t of t h e problem s e t f o r t h in C hapter I i s h y d rology. C o n s e q u e n t l y , t h i s s e c t i o n o f t h e c h a p t e r w i l l be d e v o t e d to a g en eral in tro d u c tio n to hydrologic th eo ry , a d isc u s­ sio n of stream flo w hydrology in p a r t i c u l a r , and an i n t r o d u c t i o n t o t h e r e s p o n s i v e n e s s o f t h e h y d r o l o g i c system I t o human i n t e r v e n t i o n . 1 1The g e n e r a l h y d r o l o g y and r u n o f f s e c t i o n s draw h e a v i l y on Ward ( 1 9 7 5 , c h s . 1 , 8 ) . 20 W a t e r o c c u r s s i m u l t a n e o u s l y on, u n d e r and ab o v e t h e e a r t h ' s s u r f a c e in a v a r i e t y of f o rm s , each of which i s a c o m p o n e n t o f a c o m p l e x , c o n t i n u o u s l y moving h y d r o l o g i c cycle. Figure I d e p ic ts a s im p lif ie d re p r e s e n ta tio n of the m a j o r c o m p o n e n ts o f t h e h y d r o l o g i c c y c l e . T his study i s p r i m a r i l y c o n c e r n e d w i t h t h e o c c u r r e n c e o f w a t e r on o r n e a r t h e e a r t h ' s s u r f a c e and i t s a v a i l a b i l i t y fo r use. G r o u n d w a t e r p u m pin g i n t h e Y e l l o w s t o n e B a s i n r e p r e ­ s e n t s a r e l a t i v e l y i n s i g n i f i c a n t q u a n t i t y o f w a t e r and v i r t u a l l y no g r o u n d w a t e r i s pumped f o r i r r i g a t i o n . fore, There­ a d e q u a t e m o d e l i n g o f h y d r o l o g y and w a t e r u s e i n t h e Y e l l o w s t o n e B a s i n , f o r p u r p o s e s o f t h i s s t u d y , c a n be a c c o m p l i s h e d w i t h a h y d r o l o g i c a l model t h a t c o n c e n t r a t e s on t h e s t r e a m f lo w or r u n o f f component o c c u r r i n g i n th e b a s i n . I g n o r i n g g r o u n d w a t e r pumping r e p r e s e n t s a s i g n i f i c a n t s i m p l i f i c a t i o n of t h e r e t u r n flow problem b ecau se groundw a t e r and s t r e a m f l o w s y s t e m s a r e v e r y o f t e n i n t e g r a l l y r e l a t e d v i a t h e r e t u r n flow mechanism. B u r t (1964) p r e ­ s e n t e d t h e a p p l i c a t i o n o f d y n a m i c p r o g r a m m in g t o p r o b l e m s o f c o n j u n c t i v e g r o u n d and s u r f a c e w a t e r . B redehoeft Young and (1972) a d d r e s s e d i s s u e s o f c o n j u n c t i v e g r o u n d and s u r f a c e w a t e r u se a lo n g t h e S outh P l a t t e R iv e r in C o l o r a d o a s d i d McConnen and Menon (1968) and Boyd (1968) in the G a lla tin V alley, M ontana. 21 Interception W ater vapour Soil- m o i s t u r e Gr oundwa t e r flow Figure I. Sirplified Diagram of the Hydrological Cycle. (Fran Ward, 1975) 22 Runoff R u n o f f i s t h e g r a v i t a t i o n a l l y m o t i v a t e d movement o f w a t e r i n t o and t h r o u g h c h a n n e l s on t h e e a r t h ’s s u r f a c e . H y d r o l o g i c a l l y f r u n o f f o c c u r s when p r e c i p i t a t i o n e x c e e d s e v a p o t r a n s p i r a t i o n and s t o r a g e i n and on t h e g r o u n d surface. However, an i m p o r t a n t a s p e c t o f r u n o f f i s t h a t , , w h i l e t h e o c c u r r e n c e of p r e c i p i t a t i o n t e n d s t o be v e ry d i s j o i n t and i r r e g u l a r , th e r e s u l ti n g stream flow tends to be r e l a t i v e l y c o n s t a n t . T h i s i s due p r i m a r i l y t o t h e s t o r a g e c a p a c i t y o f t h e u p p e r l a y e r s o f s o i l on t h e e a r t h w h i c h s m o o t h and d e l a y s u b s u r f a c e c o n t r i b u t i o n s t o s t r e a m flow . F ig u re 2 p r e s e n t s a d i a g r a m a t i c r e p r e s e n t a t i o n of t h e s p e c i f i c c o m p o n e n ts o f r u n o f f . T h es e a r e c h a n n e l p r e c i p i t a t i o n , o v e r l a n d f l o w , i n t e r f l o w and g r o u n d w a t e r , flow . Channel p r e c i p i t a t i o n , i.e., p recip itatio n d irectly onto th e stream channel i s u s u a lly a r e l a t i v e l y sm a ll component of r u n o f f , b e in g d i r e c t l y p r o p o r t i o n a l to th e a r e a o f t h e c a t c h m e n t b a s i n t h a t i s o c c u p i e d by s t r e a m channels, in s e m i- a r id re g io n s l i k e th e Y ello w sto n e Basin, t h i s p ro p o rtio n i s q u ite sm all. w ater f a i l s to i n f i l t r a t e O v e r l a n d f l o w o c c u r s when t h e s o i l and t r a v e l s o v e r t h e s u rfa c e to the stream channel. F a i l u r e t o i n f i l t r a t e can o c c u r f o r a number o f r e a s o n s ? i m p e r v i o u s s o i l s u b s t a n c e (bedrock, e tc .), s o il s a tu ra tio n during.high p r e c ip ita tio n or fro z e n s o i l s u r f a c e . O verland flo w i s a l s o u s u a l l y a 23 BASIN PRECIPITATION (excluding s t o r a g e interception and o t h e r los se s) INFILTRATION CHANNEL PRECIPITATION INTERFLOW (subsurface stemflow) OVERLAND FLOW RAPID INTERFLOW GROUNDWATER FLOW DE L A/ED INTERFLOW chonnel f l ow channel j ~h,_____ T L SURFACE RUNOFF I SUBSURFACE RUNOFF X QUICKFLOW BASEFLOW I ( d i r ec t runoff) (Dose r u no f f ) i I I I TOTAL RUNOFF ( s t r e o m f l ow a t Dos m o u t ' e t ) Figure 2. Diagrammatic Representation of the Runoff Process. (Fran Ward, 1975) 24 r e l a t i v e l y s m a l l com pon en t o f r u n o f f b e c a u s e t h e a f o r e m e n ­ t io n e d c o n d it io n s r a r e ly occur over la r g e area s for e x t e n s iv e p erio d s of tim e. in d icate How ever, f l o o d s , f o r e x a m p l e , t h a t th e r e are im portant e x c e p t io n s to t h i s . The w a t e r w h i c h i n f i l t r a t e s t h e s o i l w i l l become e i t h e r i n t e r f l o w , w h i c h i s t h e s h a l l o w l a t e r a l movement o f s u b s u r f a c e w a t e r , or g ro u n d w a te r. d e fin e d as subsurface ru n o ff. n ents, T hes e two c o m p o n e n ts a r e Of a l l t h e r u n o f f compo­ i n t e r f l o w i s th e most im p o r ta n t c o n t r i b u t o r to t o t a l runoff, h a v i n g i m p a c t s on i m m e d i a t e r u n o f f ( r a p i d i n t e r f l o w ) and d e l a y e d r u n o f f (delayed i n t e r f l o w ) . Ward c i t e s e m p i r i c a l h y d r o l o g ic s t u d i e s which i n d i c a t e t h a t i n t e r f l o w may a c c o u n t f o r 85 p e r c e n t o f s t r e a m f l o w p. (Ward, 241). R u n o f f i s a l t e r n a t i v e l y s u b d i v i d e d i n t o q u i c k f l o w or storm p e rio d ru n o f f , which c o n s i s t s of c h an n e l p r e c i p i ­ t a t i o n , o v e r l a n d f l o w , and r a p i d i n t e r f l o w ; and b a s e f l o w or d r y p e r i o d r u n o f f , w h i c h c o n s i s t s o f d e l a y e d i n t e r f l o w and groundw ater c o n t r i b u t i o n t o stre a m flo w . I t is th is b a s e flo w which a c c o u n ts f o r th e r e l a t i v e c o n sta n c y of stream flow d e s p ite i n t e r m i t t e n t p r e c i p i t a t i o n p a tte rn s . These f a c t o r s i n f l u e n c e th e a n n u al d i s t r i b u t i o n of s tr e a m f l o w t y p i c a l o f t h e Y e l l o w s t o n e and many o t h e r s e m i - a r i d r e g i o n s of th e West. S p r i n g and e a r l y summer f l o w s a r e v e r y h i g h , b e i n g p r e d o m i n a n t l y q u i c k f l o w r e s u l t i n g from s n o w m e l t and s e a s o n a l r a i n f a l l i n t h e s p r i n g and e a r l y 25 summer. L a t e summer, f a l l and w i n t e r f l o w s a r e l o w a s i s p r e c i p i t a t i o n d u r i n g t h a t p e r i o d and s t r e a m f l o w i s s u s t a i n e d a l m o s t e n t i r e l y by b a s e f l o w . Hydrograp hs One o f t h e t o o l s u s e d i n r u n o f f a n a l y s i s i s a h y d r o graph. A hydrograph i s a g r a p h ic a l p r e s e n t a ti o n of s t r e a m f l o w volum e p e r u n i t t i m e o v e r t i m e . A lthough used i n o t h e r c o n t e x t s , such as i n d i v i d u a l storm r u n o f f a n a l y ­ s i s , t h e h y d r o g r a p h i s a v e r y c o n v e n i e n t way t o i l l u s t r a t e r i v e r flow thoughout th e y e a r . The. h y d ro g r a p h o f a v e r a g e m onthly flo w s of th e Y ello w sto n e R iver a t Sidney for th e p e r i o d 1934 t o 1980 a r e p r e s e n t e d i n F i g u r e 3. H y d r o g r a p h s , s u c h a s F i g u r e 3 , a r e an i m p o r t a n t f o u n d a t i o n upon w h i c h w a t e r m an ag em en t and c o n t r o l p o l i c i e s are form ulated. W hile h y d ro g ra p h s s e r v e as a u s e f u l benchmark of a v a i l a b l e w a te r s u p p l i e s , i t i s im perative t h a t o t h e r f a c t o r s be c o n s i d e r e d i n c o n j u n c t i o n w i t h t h e hydrograph. An u n d e r s t a n d i n g o f t h e c o m p o n e n ts i n c l u d e d i n f l o w s m e a s u r e d i n a h y d r o g r a p h , t h e s t o c h a s t i c n a t u r e of r u n o f f , and t h e v a r i a t i o n i n f l o w s a t d i f f e r e n t p o i n t s a l o n g t h e r i v e r m u s t be c o n s i d e r e d a s w e l l . S t r e a m f l o w and I r r i g a t i o n H isto rica lly , i n many o f t h e a r i d and s e m i - a r i d r e g i o n s o f t h e w o r l d , t h e q u a n t i t y and d i s t r i b u t i o n o f s t r e a m f l o w p l a c e d q u i t e r e s t r i c t i v e l i m i t a t i o n s on t h e 26 2250 . Figure 3. Average Monthly Flow of the Yellowstone River at Sidney, Montana, for Water Years 1934-1980. 27 n a t u r e and e x t e n t o f e c o n o m i c a c t i v i t y . In much o f t h e W estern U n ited S t a t e s t h i s i s p a r t i c u l a r l y t r u e . im p o r ta n t, though l e s s o b v io u s , i s Also very t h e f a c t t h a t human a c t i v i t i e s h ave i m p a c t s w h i c h f e e d back i n t o t h e p h y s i c a l hyd rologic system . An i m p o r t a n t e x a m p le o f t h i s i s irri- / gated agricu ltu re. A g r i c u l t u r a l i r r i g a t i o n s y ste m s t y p i c a l l y d i v e r t water f r o m t h e r i v e r and c o n v e y i t t o f i e l d s t h r o u g h a n e t w o r k o f can als, d i t c h e s and o c c a s i o n a l l y p i p e s . H owev er , n o t a l l o f t h e w a t e r d i v e r t e d from t h e r i v e r i s d e l i v e r e d t o th e fie ld . Some i s t r a n s p i r e d by d i t c h b a n k f l o r a , through o p e r a t io n a l s p i l l s , some s e e p s i n t o s u b s u r f a c e a q u i f e r s and some e v a p o r a t e s . c a l d e liv e r y system , some i s l o s t The e f f i c i e n c y o f t h e p h y s i ­ conveyance e f f i c i e n c y (Ec ) , i s d efin ed as th e r a t io of th e q u a n tity of w ater d e liv e r e d to the f i e l d t o t h e q u a n t i t y o f w a t e r d i v e r t e d f r o m t h e r i v e r or Ec = w a t e r deLivet^_±(i_thm_jEl@JLA Water d i v e r t e d from t h e r i v e r L ik ew ise, not a l l of the w ater d e liv e r e d to the f i e l d w i l l b e b e n e f i c i a l l y u s e d by c r o p s . Some w i l l r u n o f f due t o e f f e c t s o f t o p o g r a p h y ( s l o p e ) , some w i l l s e e p i n t o s u b s u r f a c e a q u i f e r s and some w i l l e v a p o r a t e from t h e f i e l d surface. T h e s e e f f e c t s can be e x a g g e r a t e d i n some i n s t a n c e s due t o management i n e f f i c i e n c y t h a t r e s u l t s i n i m p r o p e r i r r i g a t i o n t i m i n g and q u a n t i t y o f a p p l i c a t i o n . 28 The e f f i c i e n c y o f t h i s c o m b i n a t i o n o f p h y s i c a l and mana­ g e r i a l f a c t o r s a t t h e farm l e v e l un it e ffic ie n c y . efficien cy. i s d efin ed as i r r i g a t i o n This i s so m etim es r e f e r r e d t o as f i e l d S p ecifica lly i r r ig a t io n unit e f f i c i e n c y (Eu) i s t h e r a t i o o f t h e q u a n t i t y o f w a t e r b e n e f i c i a l l y u s e d by c r o p s t o t h e q u a n t i t y o f w a t e r d e l i v e r e d t o t h e f i e l d or Eu = W a te r u s e d bv c r o p s Water d e l i v e r e d t o t h e f i e l d Ec a n d Eu c a n b e c o m b i n e d t o e x p r e s s a n o v e r a l l irrig a tio n efficien cy (E1 ) t h a t i s t h e r a t i o o f t h e q u a n ­ t i t y o f w a t e r b e n e f i c i a l l y u s e d by c r o p s t o t h e q u a n t i t y o f w a t e r d i v e r t e d f r o m t h e r i v e r or E 1 - Water u s e d bv c r o p s Water d i v e r t e d from t h e r i v e r T h e s e e f f i c i e n c i e s a r e b a s e d on d e f i n i t i o n s fr o m J e n s e n (19 67 ). Brosz (1981) p r o v i d e s a good summary o f t h e f a c t o r s involved in i r r i g a t i o n efficien cy . The n u m e r o u s s o u r c e s o f l o s s e s f ro m c o n v e y a n c e and f i e l d s y s t e m s c a n b e g r o u p e d i n t o tw o c a t e g o r i e s ? a b l e and n o n r e c o v e r a b l e . recover­ F i g u r e 4 shows t h e b r e a k d o w n o f i r r i g a t i o n s y s t e m l o s s e s i n t o t h e p r i m a r y c o m p o n e n ts and th e r e s u l tin g c ateg o ry of rec o v erab le lo sse s. Recoverable l o s s e s i n t h i s u s a g e s i m p l y means t h o s e l o s s e s t h a t w i l l e v e n tu a lly r e tu r n to th e n a t u r a l stre am flo w system . a r e a l s o known a s r e t u r n f l o w s . These S p e c i f i c a l l y r e t u r n flow s supply source diversions losses crop evapotranspiration subsurface surface “''â– -'-.canal evaporation I \phreatophyte and hydrophyte evapotranspiration seepage from conveyance system deep percolation from fields operational spills groundwater aquifer tailwater runoff surface drainages shallow groundwater discharge into streamflow recoverable losses return flows available for reuse downstream Figure 4. Ccrnponents of Water Loss From Irrigation Systems. deep groundwater supplies 30 a r e d e f i n e d , f o r p r e s e n t p u r p o s e s , a s . t h e sum o f s u r f a c e and s u b s u r r a c e l o s s e s f r o m c o n v e y a n c e and f i e l d s y s t e m s t h a t r e e n t e r the stre am flo w system . Figure 5 p rovides a good r e p r e s e n t a t i o n o f t h e i r r i g a t i o n and r e t u r n f l o w s y s t e m s and t h e i r r e l a t i o n t o t h e r i v e r or s t r e a m f l o w system . R e t u r n f l o w s a r e a c o m p l e x h y d r o l o g i c a l phenomenon. C o n s e q u e n t l y , w h i l e t h e p r i m a r y c o m p o n e n ts o f r e t u r n f l o w are id e n tifie d , th e c o m p lex ity of r e t u r n flo w s coupled w ith t h e c o m p l e x i t y o f t h e n a t u r a l h y d r o l o g i c s y s t e m m akes q u a n ­ t i f i c a t i o n of re tu rn flow s d i f f i c u l t . N i c k l i n and B r u s t k e r n (1981) d i s c u s s t h e p r o b l e m s f a c e d by h y d r o l o g i s t s a tte m p tin g to q u a n tify re tu rn flow s. T h i s b eco m es i m p o r ­ t a n t m e t h o d o l o g i c a l l y i f one p r o p o s e s t o i n v e s t i g a t e t h e i m p a c t o f r e t u r n f l o w s on t h e n a t u r a l s t r e a m f l o w s y s t e m . C o n c e p t u a l l y , r e t u r n f l o w s a r e an e x a m p le o f manmade o v e r l a n d f l o w and s u b s u r f a c e f l o w t h a t c o n t r i b u t e s t o q u i c k f l o w and b a s e f l o w i n h y d r o l o g i c a l l y t h e same way a s do n a tu ra l sources. Of c o u r s e , th e q u a n t i t y of r e t u r n flow i s p r o p o r t i o n a l t o t h e l e v e l of i n e f f i c i e n c y i n t h e c o n v e y a n c e and f i e l d s y s t e m s and c o n s e q u e n t l y can be c o n t r o l l e d by changes i n th e l e v e l of t e c h n i c a l e f f i c i e n c y of th e i r r i g a ­ t i o n system . How ever, one o f t h e c o m p o n e n ts o f t h e hydrograph of r i v e r flo w s ( F i g u r e 3), i s r e t u r n flow . To th e e x t e n t t h a t a hydrograph i s view ed as a "benchmark” of a v a ila b le w ater su p p lie s, i t c a n be m i s l e a d i n g i n t h i s Precipitation Inflow to Canals Evopotronspirahon from Crops Evaporation from Canals Upstream River Flow Groundwater Contribution Surface Runoff from Non-lrnaated Land Diverted for Irrigation Applied to Irrigated Land Other Evapotranspiration from Irrigated Land Irrigation Return Flow River Flow Downstream Ind & Mun. Wastes Figure 5. Natural Inflow Conceptual Diagram of the Irrigation Return Flow System. (Fran Waller, 1976) 32 s i t u a t i o n b e c a u s e t h e benchmark w i l l ch a n g e a s t h e q u a n t i t y o f return f lo w s in th e system changes. Economic T h e o r y . The f o l l o w i n g s e c t i o n o f e c o n o m i c t h e o r y s h o u l d accom­ p lish several goals. F irst, it should e s t a b l i s h th e g e n e r a l t h e o r e t i c a l n o t i o n o f w a t e r a s an e c o n o m i c good w i t h r e s p e c t t o b o t h t h e q u a n t i t y and q u a l i t y a s p e c t s o f water use. issu e, W h i l e t h i s s t u d y a b s t r a c t s from t h e q u a l i t y i t i s an i m p o r t a n t on e t h a t m u st u l t i m a t e l y be a d d r e s s e d and s h o u l d be i n c l u d e d i n t h e t h e o r e t i c a l f r a m e ­ wo rk, Second, th e th e o r y should e s t a b l i s h th e co n cep tu a l lin k a g e between th e l e v e l of i r r i g a t i o n e f f i c i e n c y t h e q u a n t i t y and q u a l i t y a s p e c t s o f w a t e r u s e . (E1) and Third, the t h e o r y s h o u l d d e l i n e a t e b e t w e e n p r i v a t e l y and p u b l i c l y p e r c e i v e d i m p a c t s o f c h a n g e s i n t h e l e v e l o f E1. t h e s e ends, Towards b e n e f i t / c o s t a n a l y s i s p r o v i d e s an a p p r o p r i a t e b a s i s f o r e v a l u a t i o n o f c h a n g e s i n t h e l e v e l o f E1. B e n e f i t / C o s t Framework When w a t e r i s u s e d a s an i n p u t i n t o t h e p r o d u c t i o n p r o c e s s o f some p r o d u c t (as o p p o s e d t o i t s v a l u e a s a c o n s u m p t i o n g o o d ) t h e dem and f o r w a t e r i s s a i d t o b e a d e r i v e d demand. That i s , i t s v a l u e i s d e r i v e d from t h e v a l u e o f t h e p r o d u c t s f o r w h i c h w a t e r i s an i n p u t . t h e demand f o r w a t e r i n a l t e r n a t i v e u s e s i s Thus, r e la t e d to the m a r g i n a l v a l u e p r o d u c t i v i t y (MVP) o f w a t e r i n e a c h u s e . 33 S p ecifically , t h e demand f u n c t i o n f o r w a t e r a s an i n p u t w i l l be e q u a l . t o t h e i n v e r s e . m a r g i n a l v a l u e p r o d u c t i v i t y c u r v e i n t h e s h o r t r u n when o n l y w a t e r i s a v a r i a b l e facto r. In th e lo n g er run, when o t h e r f a c t o r s a r e v a r i a b l e and w i l l be s u b s t i t u t e d f o r w a t e r , t h e demand f u n c t i o n f o r w a t e r w i l l b e m o r e e l a s t i c t h a n t h e MVP c u r v e . re tic a l settin g , . In a th e o ­ where o p tim a l a l l o c a t i o n o f water, i s a s s u m e d t o o c c u r , o p t i m a l i t y i s a c h i e v e d when t h e m a r g i n a l value p r o d u c tiv ity of w ater in a l l uses a re equal. From t h e s t a n d p o i n t o f w a t e r m an ag em en t p o l i c y , t h e demands f o r w a t e r a r e e x o g e n o u s l y d e t e r m i n e d and a r e f i x e d i n t h e s h o r t run. I t was e x p o u n d ed e a r l i e r t h a t u s e o f w a t e r d e p e n d s on when and w h e r e w a t e r i s a v a i l a b l e . I n a more a b s t r a c t s e n s e , t h i s can be r e s t a t e d t o s a y t h a t t h e v a l u e o f w a t e r a s p e r c e i v e d by t h e w a t e r p o l i c y p l a n n e r , i s d e p e n d e n t on q u a n t i t y and q u a l i t y o f w a t e r a v a i l a b l e , g i v e n t h e e x o g e n ­ o u s l y d e t e r m i n e d demands f o r w a t e r , a t a g i v e n t i m e and place. A b s t r a c t i n g f r o m t h e t i m e and s p a c e d i m e n s i o n s , t h e t o t a l b e n e f i t s o f w a t e r can be d e f i n e d , in g e n e r a l mathe­ m a t i c a l n o t a t i o n as (I) TBw - £(QW, Kw) w h e r e Qw r e p r e s e n t s t h e q u a n t i t y o f w a t e r a nd Kw r e p r e s e n t s 34 the q u a lity of w ater. T o t a l c o s t s o f w a t e r c a n be d e f i n e d i n t h e same g e n e r a l n a t u r e a s (2) TGw = g (Qwr Kw) At t h i s p o i n t , a f t e r m aking t h e u s u a l a s s u m p t i o n s a b o u t f i r s t and s e c o n d o r d e r c o n d i t i o n s , i.e., dim inishing m a r g i n a l b e n e f i t s and i n c r e a s i n g m a r g i n a l c o s t s , th e m argi­ n a l c o s t and b e n e f i t r e l a t i o n s h i p s c a n be d e f i n e d a s (3) MBw = ^ T B w doT" and (4) MCw = ^ T C w T his s t r a ig h t f o r w a r d b e n e f i t / c o s t a n a ly s is ( s e e F i g u r e 6) h a s b e e n r e c o g n i z e d , f o r e x a m p l e , by t h e DNRC a s p e r t a i n i n g to th e Y ellow stone R iver Basin (DNRC 1977n and 1981). However, t h e s p e c i f i c i m p a c t s o f t h e l e v e l o f r e t u r n f l o w s a n d , t h e r e f o r e , t h e l e v e l o f E1 a r e n o t f o r m a l l y taken in to account in (3) and ( 4 ) . T herefore, it i s neces­ s a r y t o p u r s u e f u r t h e r t h e q u a n t i t y and q u a l i t y a s p e c t s o f w ater. From p r e v i o u s s e c t i o n s on h y d r o l o g y t h e m a j o r d e t e r m i ­ n a n ts of th e q u a n t i t y of w ater a v a i l a b l e a re i d e n t i f i e d as n a t u r a l s tr e a m f lo w or r u n o f f , stre a m a u g m e n ta tio n w ith i 35 Figure 6. Marginal Benefits of Water Use. (MBw ) and Marginal Costs (MCv ) 36 storage f a c i l i t i e s , and r e t u r n f l o w s fro m i r r i g a t i o n . That is, (5) Qw = k ( R , S , Rf) where R r e p r e s e n t s n a t u r a l r u n o f f , S r e p r e s e n t s a r t i f i c i a l s t o r a g e and Rf r e p r e s e n t s r e t u r n f l o w from i r r i g a t i o n . W ater q u a l i t y i s a f u n c t i o n of n a t u r a l q u a l i t y co n d i­ t i o n s i n t h e r u n o f f s y s t e m and a r t i f i c i a l , i m p a c t s t h a t may b e p o s i t i v e ie., (w ater tr e a tm e n t) or n e g a tiv e ( p o i n t and n o n - p o i n t s o u r c e s o f p o l l u t i o n ) . purposes, For p r e s e n t t h e q u a l i t y i m p a c t s o f r e t u r n f l o w w i l l be s e p a ­ r a t e d from o t h e r a r t i f i c i a l q u a l i t y im p a c ts. q u ality human, T h u s, w a t e r (Kw) c a n b e e x p r e s s e d a s (6) Kw = z (R, A, Rf) where R r e p r e s e n t s q u a l i t y f a c t o r s in n a t u r a l r u n o f f , A re p re s e n ts a r t i f i c i a l q u a lity f a c to r s other than i r r i g a t i o n r e t u r n f l o w s , and Rf r e p r e s e n t s q u a l i t y f a c t o r s o f r e t u r n flow s. I t was s t a t e d e a r l i e r t h a t r e t u r n f l o w s (Rf) a r e d i r e c t l y p ro p o rtio n a l to the le v e l of i r r i g a t i o n e f f i ­ cien cy , or in g en eral (7) Rf = h (E1 ) I C onsequently, t h e l i n k b e t w e e n E1 and w a t e r b e n e f i t s and costs is estab lish ed . In g e n e r a l, su b stitu tin g (7) into 37 (6) a n d (5) a n d s u b s t i t u t i n g (6) a n d (5) i n t o ( I ) a n d (2) - r e s u l t s in (8) TBw = f {k IR, S , K E 1 )] , Z ER. Ar h (Ej ) ] } (9) TCw = g{k ER- S. I ( E 1 )] Z ER. A- h (Ej ) ] ] - The m a r g i n a l i m p a c t s o f c h a n g e s i n t h e l e v e l o f E 1 can be a p p r o p r i a t e l y d e f i n e d a s (10) MBe s = d TBw and (11) MCfis= a TCw 6 * 7 T his m a rg in a l a n a l y s i s , ( s e e F i g u r e 7) i n c o n t r a s t w i t h F i g u r e 6, c o n c e p t u a l i z e s t h e o p t i m a l l e v e l o f i r r i g a ­ tio n efficien cy r a t h e r t h a n t h e q u a n t i t y o f w a t e r use. I t i s im p o r t a n t t o u n d e rs ta n d th e d i s t i n c t i o n betw een p r i v a t e l y and p u b l i c l y p e r c i e v e d b e n e f i t s and c o s t s o f t h e l e v e l of i r r i g a t i o n e f f i c i e n c y . p o sitiv e and n e g a t i v e i m p a c t s , The e f f e c t s o f b o t h t h e i.e ., a b e t t e r d i s t r i b u t i o n t h r o u g h t i m e and q u a l i t y d e g r a d a t i o n , o f a l o w e r l e v e l of i r r i g a t i o n e f f ic ie n c y are alm ost e n t i r e l y e x te r n a l to the in d iv id u a l w ater user. T he.preceeding b e n e f i t / c o s t analy­ s i s i s m u l t i d i m e n s i o n e d i n t i m e and s p a c e and o n l y i n t h i s l i g h t i s th e i n d i v i d u a l w a te r u s e r viewed in p ro p er p e r ­ sp e c tiv e to th e e n t i r e basin. I n e c o n o m ic p a r l a n c e , t h e r e 38 Figure 7. Marginal Benefits and Marginal Costs of Irrigation Efficiency (Ej). 39 a r e b o t h p o s i t i v e and n e g a t i v e e x t e r n a l i t i e s a s s o c i a t e d w ith th e l e v e l of E j0 Thus, t h e r e i s a d i v e r g e n c e i n t h e p u b l i c and p r i v a t e p e r c e p t i o n s o f b o t h t h e m a r g i n a l b e n e f i t and c o s t c u r v e s o f F i g u r e 7 a s d e p i c t e d i n F i g u r e 8. T h e r e a r e tw o i m p o r t a n t i m p l i c a t i o n s i m p l i e d i n F i g u r e 8. F irst, t h e r e i s a d i v e r g e n c e i n t h e p r i v a t e and p u b l i c m a r g i n a l b e n e f i t and c o s t f u n c t i o n s and t h e r e f o r e w i l l r e s u l t i n a d i f f e r e n t l e v e l o f E1 b e i n g v i e w e d a s o p t i m a l a t t h e p r i v a t e and p u b l i c l e v e l s , e x c e p t i n t h e u n l i k e l y case where th e y j u s t happen t o c o in c id e . Second, g iv en t h a t t h e r e i s a d i v e r g e n c e i n b o t h t h e m a r g i n a l b e n e f i t and cost functions, it i s n o t obvious t h a t t h e r e i s a r i g i d , c o n s t a n t r e l a t i o n s h i p i n t h e tw o l e v e l s o f E1. In o th e r w o r d s , i t i s n o t c l e a r w h i c h o n e w i l l be h i g h e r a n d w h e t h e r o r n o t t h e r e l a t i o n s h i p b e t w e e n t h e tw o w i l l a l w a y s be t h e same. I t is lik ely th at site sp e c ific conditions, e.g=, h e i g h t o f p u m p in g , e n e r g y c o s t s , w h e t h e r or n o t t h e s i t e i s p a r t of a p u b lic ly su pported i r r i g a t i o n p r o j e c t , e t cetera, w i l l d e t e r m i n e w h e t h e r t h e p r i v a t e l e v e l o f E1 i s h i g h e r or low er th an t h e p u b l i c l y o p tim a l l e v e l . In g e n e r a l, th e p red o m in a n tly nonm arket environm ent of w ater use as w e ll as t h e n a t u r e o f i n s t i t u t i o n a l r e g i m e s w o u ld l i k e l y r e s u l t i n p r i v a t e l y d e te r m in e d l e v e l s of e f f i c i e n c y t h a t a r e low er t h a n w o u l d be p u b l i c l y o p t i m a l . T h e r e a r e a number o f h y d r o l o g i c and e c o n o m i c i m p l i c a ­ t i o n s of p o l i c i e s which a t t e m p t t o change th e l e v e l of 40 (Private) E x (Public) (Private) Et EJ Private Public Figure 8. Public and Private Marginal Benefits and Marginal Costs of Irrigation Efficiency (Ej). 41 i r r i g a t i o n e f f i c i e n c y and s u b s e q u e n t l y c h a n g e t h e l e v e l o f r e t u r n flo w s in th e system , A n d e r s o n (1975) d i s c u s s e s t h e i m p l i c a t i o n s of r e t u r n flo w s w i t h i n a w a te r r i g h t s regim e of p r io r a p p ro p ria tio n for i r r i g a t e d a g r i c u l t u r a l producers. J o h n s o n , G i s s e r and W e r n e r (1981) d e a l w i t h r e t u r n f l o w s i n t h e i r d i s c u s s i o n o f a g e n e r a l model o f e f f i c i e n t w ater a llo c a tio n . Dudek and H o r n e r (1981) d i s c u s s t h e e f f e c t s o f r e t u r n f l o w c o n t r o l p o l i c i e s on in com e d i s t r i b u t i o n among i r r i g a t o r s . An A l t e r n a t i v e M e t h o d o l o g i c a l A p p ro a ch C onceptually the foregoing theory i s s tra ig h tfo rw a rd . However, e m p i r i c a l a p p l i c a t i o n o f t h e t h e o r y w o u ld r e q u i r e a p o n d e r o u s am ount o f d a t a i n c l u d i n g ; d e f i n i t i o n and v a l u a ­ t io n of a l l w ater uses, k n o w l e d g e and m o d e l i n g c a p a b i l i t y o f b o t h q u a n t i t y and q u a l i t y a s p e c t s o f t h e h y d r o l o g i c system , d a t a r e g a r d i n g t h e c o s t and m a i n t e n a n c e o f i r r i g a ­ t i o n c o n v e y a n c e and f i e l d s y s t e m s a t a l t e r n a t i v e l e v e l s o f e f f i c i e n c y , and t h e d e f i n i t i o n o f an a p p r o p r i a t e p l a n n i n g h o r i z o n and d i s c o u n t f a c t o r t o i m p l e m e n t b e n e f i t / c o s t analysis. The c o m p l e x i t i e s and s t o c h a s t i c n a t u r e o f t h e h y d ro lo g ic system , th e f a c t t h a t w a ter re s o u rc e s o p e ra te in a p r e d o m i n a n t l y n o n - m a r k e t e n v i r o n m e n t and c o n s e q u e n t l y preclude r e l i a b l e v a lu a tio n d a ta , some u s e s , i.e., a e s th e tic s etc., and t h e n e b u l u s n a t u r e o f make t h i s a m ore o n e r o u s t a s k t h a n can be a d e q u a t e l y h a n d l e d i n t h i s s t u d y . 42 An a l t e r n a t i v e m o d e l i n g a p p r o a c h t h a t w i l l p r e s e n t an a p p r e c i a t i o n o f t h e i m p a c t s o f t h e l e v e l o f e f f i c i e n c y , and r e l a t e d f a c t o r s w h i l e p r e c l u d i n g an a c t u a l d e t e r m i n a t i o n o f c o s t s and b e n e f i t s i s t o u s e a “t y p i c a l year*9 m o d e l. The " t y p i c a l y e a r " m o d e l , b a s e d l o o s e l y on t h e M a r s h a l l i a n co n cep t of a r e p r e s e n t a t i v e f i r m a l l o w s us t o a b s t r a c t , in pro d u ctio n th eo ry , i n i t i a l l y a t l e a s t , from th e s t o ­ c h a s t i c n a tu r e of th e h y d ro lo g ic sy stem , of planning h o rizo n s, and t h e p r o b l e m s d i s c o u n t i n g , and d e f i n i n g , and p r o j e c t i n g l e v e l s o f a l l w a t e r uses.® valuing T h is approach u t i l i z e s a l i n e a r p r o g r a m m i n g f r a m e w o r k t o m o d el a " t y p i c a l y e a r " t h a t c o n c e n t r a t e s on i r r i g a t e d a g r i c u l t u r e , the p r i m a r y c o n s u m p t i v e u s e r o f w a t e r , and a v e r a g e l e v e l s o f r i v e r flow i n th e b a s in . O ther, l e s s c l e a r l y d e fin e d uses of w a te r a re e n te r e d as c o n s t r a i n t s in th e m odel, but not e x p l i c i t l y valued. S n y d e r (1976) u t i l i z e d l i n e a r p r o g r a m ­ m ing i n h i s m o d el t o d e t e r m i n e t h e v a l u e o f w a t e r f o r i r r i g a t i o n in th e Y ellow stone R iver Basin. The p a r t i t i o n e d l i n e a r p r o g r a m m i n g f r a m e w o r k was a l s o u t i l i z e d by Boyd (1968) and McConnen and Menon (1968) i n w a t e r m o d e l i n g ap p licatio n s. ^ C o n c e r n i n g t h e r e p r e s e n t a t i v e f i r m , Rima (1967) s t a t e s , "The f i r m i s n o t an a c t u a l f i r m , b u t r a t h e r an a n a l y t i c a l t o o l which M a rs h a ll c o n c i e v e d . . . " 43 Chapter 3 The Model I n o r d e r t o c o n s t r u c t an a n a l y t i c a l model a c c o r d i n g t o t h e g u i d e l i n e s o f C h a p t e r 2, w h i c h w i l l f u l f i l l t h e o b j e c ­ t i v e s of Chapter I f t h r e e p r e c e p t s serv ed as g u i d e l i n e s . F irst, t h e model m u s t a d e q u a t e l y s i m u l a t e t h e h y d r o l o g y o f the basin. W h i l e t h e o b j e c t i v e s p r e s c r i b e an e c o n o m ic e v a l u a t i o n o f t h e i m p a c t o f a l t e r n a t i v e r i v e r m anagem ent p o licies, s u c h i m p a c t s a r e t h e r e s u l t of i n t e r a c t i o n s w i t h th e p h y s i c a l h y d r o lo g ic system . T h e r e f o r e , e c o n o m ic e v a l u a t i o n i s c o n t i n g e n t upon s a t i s f a c t o r i l y m o d e l i n g t h e hydrologic pro cesses. S e c o n d , e c o n o m ic e v a l u a t i o n of r i v e r m an ag em en t p o l i c i e s i s c o n t i n g e n t upon s a t i s f a c t o r i l y e s t a b l i s h i n g t h e l i n k a g e b e t w e e n t h e e c o n o m ic phenomenon, w h i c h i n t h i s s t u d y i s i r r i g a t e d a g r i c u l t u r e , and t h e hydrology of th e b a s in . T hird, th e conceptual id e a s in C h a p t e r 2 i n d i c a t e a number o f a p p l i e d p o l i c y i s s u e s w h i c h a r e b ey o n d t h e s c o p e of t h i s t h e s i s , b u t m e r i t f u r t h e r in v estig atio n . A c c o r d i n g l y , t h e m odel was d e v e l o p e d w i t h enough f l e x i b i l i t y t o a l l o w t h e s e i s s u e s t o be d e a l t w i t h a t a l a t e r d a te w ith o u t s i g n i f i c a n t m o d if i c a t io n of the b a s i c mod el p r e s e n t e d h e r e . 44 The r e m a i n d e r o f t h i s c h a p t e r i s d i r e c t e d t o w a r d s p r e s e n t i n g t h e g e n e r a l l i n e a r p r o g r a m m in g f r a m e w o r k and t h e a d a p t a t i o n of t h i s fram ework t o th e s p e c i f i c problem d e a l t w ith in t h i s study. The S t a n d a r d L i n e a r Programming Pro b lem . L i n e a r p r o g r a m m in g (LP) i s a m a t h e m a t i c a l t e c h n i q u e t h a t seeks to o p tim iz e a s p e c i f i c c r i t e r i o n over a v e cto r of a l t e r n a t i v e a c t i v i t i e s s u b j e c t t o a s e t of l i n e a r co n strain ts. L e t j = ( 1 , 2 , 3 ,o.,N) r e p r e s e n t a s e t o f N a c t i v i t i e s , w h e r e Xj i s t h e q u a n t i t y o f t h e j t h a c t i v i t y a n d i=(l,2,3,...M ) represent a s e t o f M r e s o u r c e s or in p u ts i n t o t h e N a c t i v i t i e s w h e r e b^ i s t h e l e v e l o f t h e i t h resource a v a ila b le . The i n t e r d e p e n d e n c i e s b e t w e e n t h e X j ' s and b ^ ' s can be e x p r e s s e d a s a s y s t e m of M x N l i n e a r e q u a t i o n s o f t h e fo rm s a I l x I + a 12x 2 + • ° °a l n xn = b I a 12x l + a 22x 2 + • • ®a 2 n x n = b 2 amlx l + am2x 2 + • e • amnx n where Xj 2. o, j —( l , 2 , o e e N) bm 45 The a j j ' s a r e t h e c o e f f i c i e n t s o f p r o p o r t i o n a l i t y , i e . f the te c h n ic a l c o e f f i c i e n t s r e l a ti n g th e ith input to th e jth a ctiv ity . The s o l u t i o n t o t h e s y s t e m o f e q u a t i o n s i s o b t a i n e d u s i n g an a l g o r i t h m known a s t h e s i m p l e x p r o c e d u r e (D antzig, 1963). The s y s t e m o f e q u a t i o n s a r e o p t i m i z e d a c c o r d i n g t o a s p e c i f i c o b j e c t i v e f u n c t i o n Z. For e x a m p l e , t o m a x i m iz e a s e t of a c t i v i t i e s X j, (j = l ,2 ,...N ) , each w ith a v a lu e of c-i, ( j = l , 2 , . . . N ) , t h e o b j e c t i v e f u n c t i o n i s J M max (Z) = Cj x ^ J=I The s t a n d a r d l i n e a r p r o g r a m m i n g p r o b l e m i s s u b j e c t t o four g e n eral assum ptions (I) P ro p o rtio n ality : (D antzig, 1963, I n t h e LP m o d e l , pp. 32-33). th e l e v e l s of r e s o u r c e s used a re alw ay s p o r p o r t i o n a l t o th e a c t i v i t y lev el. (2) N onnegativity: A c t i v i t i e s a r e alw ays r e s t r i c t e d to z e r o or p o s i t i v e lev els. (3) The a d d i t i v i t y a s s u m p t i o n r e q u i r e s t h a t A d d itiv ity : e a c h r e s o u r c e or i n p u t be c o m p l e t e l y a c c o u n t e d f o r i n t h e m o d e l , i e . t h e t o t a l amoun t o f i n d i v i d u a l r e s o u r c e use i m p l i e d by t h e sum o f a l l a c t i v i t i e s m u s t b e e q u a l t o t h e to tal (4) amou nt o f e a c h r e s o u r c e a v a i l a b l e . L inear O b je c tiv e F unction: Each o f t h e a c t i v i t i e s in t h e LP p r o b l e m m u s t c o n t r i b u t e t o t h e o b j e c t i v e f u n c t i o n i n a l i n e a r f a s h i o n r e g a r d l e s s o f t h e l e v e l of t h e a c t i v i t y . 46 In a d d itio n , t h e g e n e r a l LP f r a m e w o r k i m p l i e s t h a t t h e r e a r e a f i n i t e number of a c t i v i t i e s and r e s o u r c e s and th a t th ese are i n f i n i t e l y d iv is ib le . In a d d i t i o n to d e te rm in in g th e o p tim al a l l o c a t i o n of s c a r c e r e s o u r c e s among a l t e r n a t i v e u s e s , t h e LP s o l u t i o n w i l l i n c l u d e c a l c u l a t e d shadow p r i c e s f o r e a c h r e s o u r c e co n strain t. T h ese shadow p r i c e s r e p r e s e n t t h e i m p u t e d v a l u e s of a m a r g i n a l u n i t o f e a c h o f t h e r e s o u r c e s . More s p e c i f i c a l l y , t h e shadow p r i c e o f a p a r t i c u l a r r e s o u r c e i s t h e v a l u e o f an a d d i t i o n a l u n i t o f t h e r e s o u r c e u s e d i n t h e h i g h e s t v a l u e d a c t i v i t y m in u s t h e o p p o r t u n i t y c o s t o f t h e resource in a lte r n a tiv e uses. T herefore, o p tim al a l l o c a t i o n of re s o u rc e s, i n l i g h t of an t h e c a l c u l a t e d shadow p r i c e of a r e s o u r c e r e p r e s e n t s t h e m a r g i n a l v a l u e of t h a t resource. The v a l i d i t y o f t h e shadow p r i c e a s an e s t i m a t e of th e t r u e m a r g in a l v a lu e of t h a t r e s o u r c e t o s o c i e t y d e p e n d s on t h e c o m p l e t e n e s s o f t h e model i n r e f l e c t i n g so c ia l opportu n ity costs. The l i n e a r p r o g r a m m i n g f r a m e w o r k i s w e l l s u i t e d t o t h e needs of the study. As a m e t h o d o l o g i c a l a p p r o a c h i t f u l ­ f i l l s two c r i t i c a l needs of t h e s tu d y . F irst, it is a model o f t h e a l l o c a t i o n o f a s c a r c e r e s o u r c e among a number of a l t e r n a t i v e uses. criterio n , Se c o n d , by o p t i m i z i n g a s p e c i f i c i t p r o v i d e s t h e m ec h an ism w h e r e b y t h e i m p a c t s of f a c t o r s a f f e c t i n g t h e s c a r c e r e s o u r c e can be m e a s u r e d . However, a s e s t a b l i s h e d i n C h a p t e r s I and 2, b o t h t h e 47 s c a r c i t y o f w a t e r r e s o u r c e s and t h e i m p a c t s o f r e t u r n f l o w s i n t n e Y e l l o w s t o n e $ a s i n a r e f u n c t i o n s o f t i m e and s p a c e dim ensions. Thus t h e a d a p t a t i o n o f t h e l i n e a r p ro g r a m m in g m o d el t o i n c l u d e t h e s e d i m e n s i o n s i s a f i r s t p r e r e q u i s i t e . S p a t i a l Dimension To f a c i l i t a t e t h e m o d e l i n g o f an a r e a a s v a s t a s t h e Y e llo w sto n e B a sin , th e r e g io n i s d iv id e d i n t o n in e sub­ basins. T h ese n i n e s u b - b a s i n s ( s e e F i g u r e 9 and T a b l e I) r e p r e s e n t t h e m a j o r t r i b u t a r y and m a i n s t e m r e g i o n s o f t h e Y e l l o w s t o n e B a s i n and a r e b a s e d on a g g r e g a t i o n s o f h y d r o l o ­ g i c s u b d r a i n a g e s u s e d by t h e DNRC (1970). The d r a i n a g e b a s in c o m p o s itio n of th e nine a r e a s a re a ls o l i s t e d in T able I. Each o f t h e n i n e s u b - b a s i n s i s m o d eled i n d i v i d u a l l y i n t h e l i n e a r p r o g r a m m in g f r a m e w o r k and c o m b i n e d , a l o n g w i t h a p p r o p r i a t e l i n k a g e s among t h e s u b - b a s i n s , i n a p a r t i t i o n e d l i n e a r programming fram ew ork. The Y e l l o w s t o n e R i v e r B a s i n , i n t n e c o n t e x t o f m a i n s t e m r i v e r f l o w and t r i b u t a r y i n f l o w , can be v i e w e d s p a t i a l l y a s a n e t w o r k s i m i l a r t o F i g u r e 10 a n d , when a d a p t e d t o t h e p a r t i t i o n e d LR f r a m e w o r k , resu lts i n a m a t r i x f o r m a t s i m i l a r t o F i g u r e 11 w h e r e t h e s u b - b a s i n s u b m a tr i c e s a r e s e q u e n t i a l l y l i n k e d t o form t h e b a s in - w id e model. The l i n e a r p r o g r a m m in g m o d el w h i c h was d e v e l o p e d t r e a t s a l l a c t i v i t i e s w i t h in a su b -b a s in as i f th ey occur a t one p o i n t i n s p a c e . Thus t h e m odel a c t s a s i f t h e n i n e Y e II o w s t o n e R iver B asin ’€ i.lO wSTO NE e . vc * BAS N CoM iiibtiiN q Riviu B asIns 1 2 3 4 5 6 7 • ♦ Upper Yellowstone Clorks Fork Yellowstone Billings Area Bighorn Mid-Yellowstone Tongue Kinsey Area Powder Lower Yellowstone Sn CMU*NP I M-CONt V O..SON P B- Ai Rl E L - x y ' •0 y I I I O $ «00 ! T ^ F r T f ussCu W H E A T L A N D J ' NCtuJ GOLDEN - V A L L E Y r— T - ' iJ > \ J v -L -ji-z - r X f 'L.. YELLOWSTONE V ® [ S T l L L W A T t R X C A L L A T Mn I Z «00 â– «o»t*»»» WzL W t A C H E * - lPiTfl..9//( il =& < . "J\ / • u Ty--TXx £n oo X " ' o , - 1*. ? C A R T E R DAKO 2 / Itv T ^ T H" jfe=1 -j _i_______ SC-----5S— WYOMING N A T I O N A L F A R K Figure 9. .J L . Fiqunt I The Nine Planning Sub-basins of the Yellowstone River Basin (From D N R C , 1977d) 49 Sub-basin •h ia Table I . The N i n e S u b - b a s i n s o f t h e Y e l l o w s t o n e R B a s i n and A s s o c i a t e d H y d r o l o g i c D r a i n a g e Name H ydrologic Basin I Upper Y ellow stone 43A , 43B , 43C , 4 3 B J , 43QJ 2 C l a r k s Fo rk 43D 3 B illin g s 43Q, 4 Bighorn 43N, 43P, 5 M id-Y ellow stone 43KJ f 42A 6 Tongue 42B , 7 Kinsey 42K 8 Powder . 421, 42J 9 Lower Y ellow stone 42L, 42M 43E 42C 430 43BV, Ul O Figure 10. The Nine Planning Sub-basins as a Network. O b l e c t i v e Row S ub-basin L Sub-basin 2 S ub-basin 3 lin k a g e s S ub-basin 4 S ub-basin 5 I Linkages S ub -b asin 6 S ub-basin 7 I Ul Linkages H S ub-basin 6 Sub-basin 9 I Figure 11. Linkages The Nine Sub-basins Submatrices in the Partitioned Linear Programming Framework 52 s u b - b a s in s of the Y e llo w s to n e B a sin are nine i n d i v i d u a l p o in ts in space. F u r t h e r s p a t i a l r e a l i s m c o u l d be added t o t h e model by f u r t h e r d i v i d i n g t h e s u b - b a s i n s i n t o s m a l l e r regions. The n i n e a r e a b r e a k d o w n was c h o s e n f o r t h r e e r e a s o n s . F irst, t h e n in e a r e a breakdown i s c o m p a tib le w i t h o t h e r a n a l y t i c a l work done i n t h e Y e l l o w s t o n e B a s i n ( B o r i s and K r u t i l l a f 1980 and DNRCf 1977 d). T h e r e f o r e , t h e r e s u l t s of t h i s s t u d y w i l l be c o m p a t i b l e w i t h t h o s e o f o t h e r s t u d i e s . T his w i l l f a c i l i t a t e th e a b i l i t y of w ater p la n n in g o f f i ­ c i a l s to i n t e r p r e t th e r e s u l t s p re se n te d here. Seco n d , the n in e a r e a breakdown w orks q u i t e w e l l t o f a c i l i t a t e th e m eshing of a l t e r n a t i v e d a t a s o u r c e s . Much o f t h e e c o n o m ic and a g r i c u l t u r a l d a t a a r e c o u n t y b a s e d w h e r e a s t h e h y d r o l o g i c d a t a a r e b a s e d on h y d r o l o g i c s u b - b a s i n s . a d d itio n a l sub-basin s u b s ta n tia lly t h e b a s i n - w i d e model. T herefore, T hird, each in c r e a s e s th e s iz e of i n o r d e r t o c o n s e r v e on b o t h c o m p u t a t i o n a l t i m e and t i m e s p e n t i n m odel c o n s t r u c ­ t i o n , t h e model s h o u l d be no l a r g e r t h a n r e q u i r e d t o d e a l w i t h th e problem under i n v e s t i g a t i o n . Time D i m e n s io n W h i l e i t i s t h e i n t e n t o f t h i s s t u d y t o u t i l i z e an a n n u a l " t y p i c a l y e a r " t y p e mod el u t i l i z i n g o f annual r i v e r f l o w s , average l e v e l s t h e n a t u r e o f t h e h y d r o l o g i c and a g r i c u l t u r a l p r o c e s s e s n e c e s s i t a t e m odeling th e c h a r a c t e r ­ i s t i c s of flo w w i t h in th e y e a r . . This i s a cco m p lish ed in 53 t h e LP mod el by r e p l a c i n g s i n g l e a c t i v i t i e s and c o n s t r a i n t s b a s e d on a n n u a l v a l u e s w i t h a s e r i e s r e p r e s e n t i n g m o n t h l y values. For p u r p o s e s o f t h i s s t u d y t h e LP m odel c o n t a i n s 5 t i m e i n t e r v a l s r e p r e s e n t i n g t h e 5 m o n th s . May t h r o u g h S eptem ber, th e r e b y r e p r e s e n t i n g th e m a j o r i t y of t h e i r r i g a ­ t i o n season. I n s t e a d o f one ( a n n u a l ) w a t e r b a l a n c e e q u a tio n f o r each s u b - b a s in , th e re a re f iv e balance e q u a t i o n s , one f o r e a c h o f t h e f i v e m o n th s o f t h e i r r i g a ­ t i o n s e a s o n . The h y d r o l o g y o f t h e b a s i n r e q u i r e s t h a t t h e s e f i v e t i m e i n t e r v a l s be i n t e r r e l a t e d due t o t h e n a t u r e o f r e t u r n f l o w s and c r o p c o n s u m p t i v e u s e o f w a t e r . Expansion of th e model to encom pass a l l p e r i o d s of th e y e a r i s s t r a i g h t f o r w a r d and c o u l d be a c c o m p l i s h e d by an i n c r e a s e i n d i m e n s i o n o f t h e m o d e l. The H y d r o l o g i c Model The movement o f w a t e r t h r o u g h t i m e and s p a c e i s s i m u ­ l a t e d m a t h e m a t i c a l l y by m a t e r i a l b a l a n c e e q u a t i o n s . I) O u t f l o w t = I n f l o w t - U se t E q u a tio n I i s a s im p le v e r s i o n of such a b a la n c e e q u a tio n w h i c h s a y s t h a t t h e o u t f l o w o f w a t e r fr o m a s u b - b a s i n i n t i m e i n t e r v a l t m u s t be e q u a l t o t h e i n f l o w m in u s t h e u se in tim e i n t e r v a l t. In t h i s exam ple, i n f l o w and o u t f l o w m u s t be i n t e r p r e t e d more b r o a d l y t h a n j u s t s t r e a m f l o w t o i n c l u d e " e f f e c t i v e " i n f l o w and o u t f l o w su c h a s i n t e r n a l p r e c i p i t a t i o n , t e m p o r a r y g r o u n d w a t e r i n f i l t r a t i o n , and 54 storage. Of c o u r s e "Use^" c a n be s e p a r a t e d i n t o c a t e g o r i e s f o r any number o f a l t e r n a t i v e u s e s . R ew riting eq u atio n I as la) Uset + O u t f l o w t = I n f l o w t s e t s th e s ta g e f o r i n c o r p o r a t i o n of th e m a t e r i a l b a la n c e e q u a t i o n i n t o t h e l i n e a r programming fram ew ork where in f lo w i s a s p e c i f i e d r i g h t - h a n d s i d e (RHS) and u s e s and o u t f l o w are a c t i v i t i e s . By f o r c i n g t h e s t r i c t e q u a l i t y , flow becomes a r e s i d u a l a c t i v i t y such t h a t , "used", th e out­ any w a t e r n o t m u s t become o u t f l o w and move i n t o t h e n e x t s u b - b a s i n d o w n s tr e a m ? t h u s s i m u l a t i n g t h e " f l o w " o f t h e r i v e r . F i g u r e 12 i s a r e p r e s e n t a t i o n o f t h e m a j o r c o m p o n e n ts of t h e model u se d i n t h i s s t u d y . A ll of th e w a t e r w hich e n t e r s a s u b - b a s i n m u s t e i t h e r be d i v e r t e d f o r i r r i g a t i o n , u s e d f o r e n e r g y p r o d u c t i o n , m u n i c i p a l , o r minimum f l o w ( in s tr e a m ) r e q u i r e m e n t s or s e n t dow nstream as u n d i v e r t e d flow . In t h i s c a s e , th e u n d iv e r te d flow i s t h e r e s i d u a l a c t i v i t y t o e n s u r e t h a t t h e w a t e r e q u a t i o n b a l a n c e s , and t h e r e f o r e i s a component of o u t f lo w . Minimum f l o w r e p r e ­ s e n t s minimum r i v e r l e v e l s r e q u i r e d t o m a i n t a i n w i l d l i f e h a b i t a t and w a t e r q u a l i t y and i s one of t h r e e c a t e g o r i e s of e x o g e n o u s u s e s , b u t , a s i t i s an i n s t r e a m u se i t i s also a component of o u tf lo w . The e x o g e n o u s u s e c a t e g o r i e s ? energy p ro d u c tio n , m u n i c i p a l , and minimum f l o w e n t e r t h e model a t s p e c i f i e d In a T Diversion — V Energy use Requirements for Agricxilture Municipal use Reqxiirements Minimum flew Requirements Y~ Not Diverted -^Outflow L Conveyance Loss Return flow from Conveyance Conveyance to Field V Inflow to next Sub-basin Total Return flow/sub-basirr A L Loss during field use Use in field Figure 12. Return flow from rield xose Meet net irrigation Requirements Flow Chart of t h e Principal C o m p o n e n t s of t h e . LP Model. Maximum returns to Agricultxire Crops 56 l e v e l s , by t i m e i n t e r v a l a n d s u b - b a s i n , i n t h e f o r m o f row c o n s t r a i n t s w h i c h m u s t be s a t i s f i e d * Minimum f l o w c o n ­ s t r a i n t s , b a s e d on i n s t r e a m r e s e r v a t i o n s f o r f i s h , w i l d l i f e , and w a t e r q u a l i t y m a i n t e n a n c e g r a n t e d by t h e B o a r d o f N a t u r a l R e s o u r c e s and C o n s e r v a t i o n , represent a sig n ific a n t p o r tio n of th e w ater a v a i la b l e in th e r i v e r . E n erg y and m u n ic i p a l use of w a t e r a t th e p r e s e n t tim e a r e s m a ll r e l a ­ t i v e to t o t a l r iv e r flow . However, t h e i n c l u s i o n of t h e s e c o m p o n e n t s i n t h e m od el g r e a t l y i n c r e a s e s i t s f l e x i b i l i t y t o s im u la te s c e n a r i o s of in c re a s e d l e v e l s of th e s e a l t e r n a ­ tiv e uses. The I r r i g a t e d A g r i c u l t u r e Model M o d e l in g t h e movement o f i r r i g a t i o n w a t e r f r o m t h e r i v e r t o t h e p l a n t t h r o u g h t h e c o n v e y a n c e and f i e l d s y s t e m s i s a c c o m p l i s h e d v i a a n e t w o r k o f t r a n s f e r a c t i v i t i e s and balance e q u a tio n s. The c o n v e y a n c e and f i e l d u s e p r o c e s s e s a r e s i m u la t e d w ith t r a n s f e r a c t i v i t i e s which d i v e r t w a ter f ro m t h e " r i v e r " , (the w ater b a la n ce e q u a tio n ), and d e l i v e r a p o r t i o n of t h a t w a te r t o t h e p l a n t fo r i t s use. Not a l l of th e d i v e r t e d w a t e r i s d e l i v e r e d because of conveyance and f i e l d l o s s e s , th a t is, b e c a u s e c o n v e y a n c e and f i e l d e f f i c i e n c i e s a r e l e s s t h a n 100 p e r c e n t . The d i v e r s i o n , c o n v e y a n c e , f i e l d u s e , and c r o p n e t i r r i g a t i o n r e q u i r e m e n t p o r t i o n o f t h e l i n e a r p r o g r a m m i n g model i s d e p i c t e d c o n c e p ­ tu ally i n t h e t a b l e a u p r e s e n t e d i n F i g u r e 13. presents, as detached c o e f f i c i e n t s , The t a b l e a u t h o s e p o r t i o n s of t h e D ivert Water F i e l d Use o f Water Crop A ctivity RHS Inflow Water B a l a n c e E q u a t i o n 1 Conveyance E q u a t i o n -E c I ^ F i e l d Use E q u a t i o n I = 0 = 0 —> - EU ^ / N^I.R. Ec = c o n v e y a n c e e f f i c i e n c y Eu = i r r i g a t i o n u n i t e f f i c i e n c y N .I.R . = net i r r i g a t i o n requirem ents F i g u r e 13. "Movement" o f W ater From t h e R i v e r t o Cro p s i n t h e LR Model 58 r e l e v a n t e q u a t i o n s w h i c h show how t h e model e s t a b l i s h e s t h e l i n k a g e b e t w e e n t h e c r o p p i n g a c t i v i t i e s and r i v e r f l o w v i a t h e c o n v e y a n c e and f i e l d s y s t e m s . Thus, i n an a b s t r a c t s e n s e , t h e "m ovem ent" of w a t e r f ro m t h e r i v e r t o t h e c r o p i s m o d e l e d a s d e p i c t e d by t h e d i r e c t i o n a l a r r o w s . For i l l u s t r a t i o n e a s e , t h e t a b l e a u o n l y shows t h e e q u a t i o n s f o r a s in g le tim e i n t e r v a l . R e f e r r i n g t o F i g u r e 13, and a s s u m i n g f o r s i m p l i c i t y t h a t conveyance e f f i c i e n c y efficien cy (Ec ) and i r r i g a t i o n (Eu ) a r e b o t h 50 p e r c e n t , w a t e r i s d i v e r t e d from th e r i v e r , w i l l be d e l i v e r e d t o t h e f i e l d . unit (field) i f one a c r e - f o o t o f then o n e -h a lf a c r e - f o o t Of t h e w a t e r d e l i v e r e d t o t h e f i e l d , o n e - h a l f w i l l be d e l i v e r e d t o t h e p l a n t f o r c o n su m p tiv e use. Thus, o f t h e o r i g i n a l one a c r e - f o o t d i v e r t e d fr o m t h e r i v e r , o n l y o n e - q u a r t e r a c r e - f o o t was u l t i m a t e l y u s e d by t h e p l a n t . A d i f f e r e n t s e t of th e se ro w s and a c t i v i t i e s e x i s t s f o r e a c h t i m e i n t e r v a l (month) and s u b - b a s i n . A l t e r n a t i v e i r r i g a t e d c r o p s c a n be p r o d u c e d in the su b -b asin s. The c r o p p i n g a c t i v i t i e s a r e l i n k e d t o t h e h y d r o l o g i c m o d el v i a n e t i r r i g a t i o n r e q u i r e m e n t s f o r e a c h c r o p w h i c h a r e s p e c i f i e d by m onth and m u s t be s a t i s ­ f i e d i n o r d e r t o "grow" a p a r t i c u l a r c r o p . In t h i s sense t h e model i s l i m i t e d t o a s i n g l e i r r i g a t i o n schem e f o r e a c h c ro p in each su b -b a sin . I n o t h e r w o r d s , t h e c u r r e n t model does n o t p e r m i t a c ro p to have a lo w e r y i e l d and hence 59 re q u ire l e s s w ater. However, t h e model c o u l d be e x p a n d e d t o i n c l u d e such a l t e r n a t i v e s i f d a t a were a v a i l a b l e . The model d o e s n o t a t t e m p t t o s i m u l a t e t h e e n t i r e a g r i c u lt u r a l production process for W ith th e e x c e p t i o n o f w a t e r , each of t h e cro p s. t h e model a s s u m e s t h a t a l l o t h e r p r o d u c t i o n i n p u t s a r e a v a i l a b l e and p r o d u c t i o n re q u ire m e n ts a re s a t i s f i e d f o r each crop. The t o t a l number of i r r i g a t e d a c r e s in each su b -b a s in a re c o n s tr a in e d , but t h e o p tim u m c r o p p i n g p a t t e r n i s d e t e r m i n e d by t h e l i n e a r program m ing model. The m odel i m p l i c i t l y a s s u m e s t h a t e a c h s u b - b a s i n i s c h a r a c t e r i z e d by hom ogeneous s o i l t y p e s , f a r m i n g s y s t e m s , m an a g em en t l e v e l s , etc. Thus, i t t a c i t l y assum es t h a t each s u b - b a s i n i s compo sed o f a s e r i e s o f a v e r a g e o r t y p i c a l farm s t h a t are a l l a lik e . The O b j e c t i v e F u n c t i o n The o b j e c t i v e f u n c t i o n i s t h e d r i v i n g f o r c e o f t h e l i n e a r p r o g r a m m i n g m o d e l. In t h i s model, t h e o b j e c t i v e f u n c t i o n i s s p e c i f i e d t o m axim ize r e t u r n s over v a r i a b l e c o s t s to th e v e c to r of cro p s in each a re a . In a d d it i o n th e o b j e c t i v e f u n c t i o n c o n t a i n s a n o m i n a l c h a r g e o f $5.00 p e r a c re -fo o t for div ersio n a c t i v i t i e s . T his i s c o n s t a n t f o r a l l s u b - b a s i n s and i s n o t an a c t u a l d i v e r s i o n c o s t b u t i s i n t e n d e d t o i n s u r e t h a t t h e model i s e f f i c i e n t , ie., d o e s n ' t d i v e r t any more w a t e r t h a n n e c e s s a r y f o r c r o p u s e . . 60 The B a s i n - w i d e Model The l i n k a g e s b e t w e e n t h e n i n e s u b - b a s i n s t h a t r e s u l t i n a b a s i n - w i d e model o f r i v e r f l o w c o n s i s t o f two compo­ n e n t s ; i n s t r e a m f l o w b e t w e e n s u b - b a s i n s and r e t u r n f l o w s from i r r i g a t i o n . R i v e r f l o w f ro m an u p s t r e a m s u b - b a s i n t o an i m m e d i a t e l y d o w n s t r e a m s u b - b a s i n c o n s i s t s o f tw o o u t f l o w components. The tw o o u t f l o w c o m p o n e n ts of a s u b - b a s i n a r e t h e u n d i v e r t e d w a t e r w h i c h s a t i s f i e s t h e minimum f l o w r e q u i r e m e n t s and t h e r e s i d u a l a c t i v i t y , v e rte d flow . i.e., other undi­ T h ese o c c u r i n t h e l i n e a r p r o g r a m m i n g model as a t r a n s f e r betw een th e w a te r b a la n c e e q u a t io n s of th e u p s t r e a m and d o w n s t r e a m s u b - b a s i n s by t i m e i n t e r v a l . F i g u r e 14 i s a c o n c e p t u a l t a b l e a u r e p r e s e n t i n g t h i s t r a n s ­ f e r o f i n s t r e a m f l o w f ro m an u p s t r e a m s u b - b a s i n t o an im m e d ia te ly downstream s u b - b a s i n f o r a g iv en tim e i n t e r v a l . The t a b l e a u i s a s i m p l i f i e d r e p r e s e n t a t i o n o f t h i s t r a n s f e r p r o c e s s and i n c l u d e s o n l y t h e n e c e s s a r y p o r t i o n s o f t h e equations involved. Thus, i n F i g u r e 1 4 , e a c h a c r e - f o o t o f w a t e r e n g a g e d by t h e minimum f l o w a c t i v i t y o f t h e u p s t r e a m a r e a , t o m ee t t h e minimum f l o w c o n s t r a i n t s f o r t h a t s u b - b a s i n , w i l l be t r a n s ­ f e r r e d t o th e b a la n c e e q u a tio n of th e s u b - b a s in im m e d ia te ly dow nstream . S i m i l a r l y , f o r e a c h a c r e - f o o t o f w a t e r en g ag ed by t h e r e s i d u a l u n d i v e r t e d f l o w a c t i v i t y of t h e u p s t r e a m s u b - b a s i n , t o b a l a n c e t h e w a t e r b a l a n c e e q u a t i o n , an Minimum Flow "Not D iverted" RHS Water B a l a n c e E q u a t i o n Inflow U p s tr e a m S u b - b a s i n W ater B a l a n c e E q u a t i o n Inflow Downstream S u b - b a s i n F i g u r e 14 "Movement" o f I n s t r e a m Flow From an U p s tr e a m S u b - b a s i n t o an I m m e d i a t e l y Downstream S u b - b a s i n . p 62 a c r e - f o o t w i l l be t r a n s f e r r e d t o t h e w a t e r b a l a n c e e q u a t i o n of th e s u b - b a s i n im m e d ia te ly downstream . The s i g n c o n v e n t i o n o f t h e LP m o d e l i n t h i s s t u d y u s e s p o s i t i v e c o e f f i c i e n t s t o r e p r e s e n t " d e m a n d e r s " and n e g a t i v e c o e f f i c i e n t s t o r e p r e s e n t " s u p p l i e r s 61 f o r t r a n s f e r a c t i v i t i e s and b a l a n c e e q u a t i o n s . T h e r e f o r e t h e minimum f l o w and t h e r e s i d u a l u n d i v e r t e d f l o w a c t i v i t i e s a r e "d em a n d in g " w a t e r f r o m t h e u p s t r e a m s u b - b a s i n and " s u p p l y i n g " w a t e r t o t h e s u b - b a s i n i m m e d i a t e l y d o w n s tr e a m . I f t h e d o w n s t r e a m s u b - b a s i n h a s no i n t e r n a l s t r e a m f l o w s o u r c e , t h e n t h e RHS o f t h e w a t e r b a l a n c e e q u a t i o n w i l l b e z e r o s i n c e t h e i n f l o w i n t o t h a t s u b - b a s i n e n t e r s oh t h e l e f t s i d e of th e w a te r b a la n c e e q u a t io n , from th e u p stre am s u b - b a s in . i.e., the outflow A ll of th e t r i b u t a r y sub­ b a s i n s and t h e u p p e r m a i n s t e m h a v e w a t e r e n t e r i n g a c r o s s t h e s t a t e l i n e f r o m Wyoming a n d / o r g e n e r a t e s i g n i f i c a n t q u a n t i t i e s o f s t r e a m f l o w w i t h i n t h e s u b - b a s i n and t h e r e f o r e h av e p o s i t i v e RHS on t h e w a t e r b a l a n c e e q u a t i o n s . However, most of th e m ainstem s u b - b a s i n s a r e l o c a t e d in th e p l a i n s region of the b a sin , i.e., they a re not headw ater a re as, and t h e r e f o r e do n o t make s i g n i f i c a n t c o n t r i b u t i o n s t o stream flow .1 The r e t u r n f l o w s t h a t r e e n t e r t h e s u r f a c e f l o w s y s t e m a r e so m e w h at more c o m p l i c a t e d b o t h w i t h r e g a r d t o t h e t i m e 1 T h i s a s s u m p t i o n i s m o d i f i e d so m e w h at i n t h e c a l i b r a t i o n pro ce d u re d e s c r i b e d in C hapter 5, 63 an d s p a c e d i m e n s i o n s . S p a t i a l l y , i t i s assumed i n t h i s m o d el t h a t i n t h e t r i b u t a r y and u p p e r m a i n s t e m s u b - b a s i n s , (1,2,4,6,8), w a t e r i s d i v e r t e d by i n d i v i d u a l u s e r s w h i c h a r e s c a t t e r e d hom ogeneously th r o u g h o u t t h e s u b - b a s i n s such t h a t v i r t u a l l y a l l o f t h e r e t u r n f l o w fr o m i r r i g a t i o n i s a v a ila b le for r e u s e by an i r r i g a t o r Most o f t h e m a i n s t e m s u b - b a s i n s i n t h a t same s u b - b a s i n . (3,5,7,9), in c o n tr a s t , are c h a r a c t e r i z e d by d i s t i n c t d i v e r s i o n p o i n t s f o r l a r g e i r r i ­ g a t i o n p r o j e c t s and c o n s e q u e n t l y r e t u r n f l o w s a r e n o t a v a i l a b l e u n t i l t h e n e x t s u b - b a s in downstream . The m ajo r e x c e p t i o n t o t h i s a s s u m p t i o n i s s u b - b a s i n 3, t h e B i l l i n g s a r e a , which i s som eth in g of a t r a n s i t i o n a re a . Conse ­ q u e n t l y , i n t h e B i l l i n g s s u b - b a s i n i t i s a s s u m e d t h a t 60 p e rc e n t of i t s i n t e r n a l l y g e n e ra te d r e tu r n flo w s a re a v a i l a b l e f o r r e d i v e r s i o n w i t h i n s u b - b a s i n 3 and 40 p e r c e n t w i l l n o t be a v a i l a b l e f o r r e u s e u n t i l s u b - b a s i n 5 , w hich i s im m e d ia te l y dow nstream . R etu rn f l o w s a l s o c r o s s over tim e i n t e r v a l s because of t h e i r delayed n a tu re . sion, T h u s, r e t u r n f l o w s fr o m a May d i v e r - . f o r e x a m p l e , w i l l c o n t r i b u t e t o t h e May w a t e r b a l a n c e eq u ation, th e June w ater balance e q u atio n , e t cetera. R eservoirs The m o d el a l s o i n c l u d e s s i m u l a t i o n s o f t h e tw o l a r g e s t r e s e r v o i r s i n t h e b a s i n , t h e Y e l l o w t a i l Dam on t h e B i g H orn River ( s u b - b a s i n 4) and t h e Tongue R e s e r v o i r on t h e Tongue R iver (sub-basin 6). 64 The a c t i o n s o f a r e s e r v o i r a r e s i m u l a t e d by a s e r i e s o f t r a n s f e r a c t i v i t i e s and b a l a n c e e q u a t i o n s . F i g u r e 15 d e p ic ts c o n c e p tu a lly th e s im u la tio n of r e s e r v o ir a c t i v i ­ t i e s fo r a p a r t i c u l a r tim e i n t e r v a l . in terv al t, For e x a m p l e , i n t i m e t h e w a t e r " s u p p l i e d " t o t h e r e s e r v o i r comes f r o m e i t h e r w a t e r h e l d i n t h e p r e v i o u s t i m e i n t e r v a l and n o t r e l e a s e d or w a t e r h e l d f r o m r i v e r f l o w i n t h i s t i m e in terv al. The b a l a n c e e q u a t i o n f o r r e s e r v o i r u s e i n e a c h tim e i n te r v a l are su b je ct to a s t r i c t e q u a lity , i.e., all o f t h e w a t e r " s u p p l i e d " m u s t be demanded i n some a c t i v i t y . Thus, t h e w a t e r " s u p p l i e d " t o t h e r e s e r v o i r , in terv al, sub-basin, in each tim e cart be "demanded" f o r e i t h e r r e u s e i n t h a t same r e l e a s e t o t h e s u b - b a s i n im m e d ia te ly dow nstream , or t r a n s f e r r e d t o t h e n e x t t i m e i n t e r v a l a s r e s e r v o i r storage. In o th e r words, th e r e s e r v o ir balance e quation f o r a p a r t i c u l a r t i m e i n t e r v a l s a y s t h a t t h e sum o f t h e q u a n t i t y of w a ter h e ld over from th e p r e v io u s tim e i n t e r v a l p l u s t h e q u a n t i t y h e l d fr o m r i v e r f l o w i n t h i s t i m e i n t e r ­ v a l m ust e q u a l th e amount of w a te r used in th e s u b - b a s in in t h i s tim e i n t e r v a l p l u s t h e amount r e l e a s e d downstream in t h i s tim e i n t e r v a l p l u s t h e amount h e ld over i n t o t h e n e x t tim e i n t e r v a l . The use o f p o s i t i v e and n e g a t i v e C j "s i n t h e o b j e c t i v e f u n c t i o n a l l o w s t h e m odel t o s i m u l a t e any number o f p o s ­ s i b l e r e s e r v o i r m anagem ent s c e n a r i o s , w h i c h may be d e s i r e d , a g a i n c o n t r i b u t i n g t o t h e f l e x i b i l i t y of t h e m o d el. Transfer water from t-1 to t Water Balance Equation (t) Reservoir Balance Equation (t-1) Reservoir Balance Equation (t) Store water in t Release water downstream in t I I -I -I RHS = Inflow I Reservoir Balance Equation (t+1) t = time interval Figure 15. Release Transfer water water from back into t to t+1 sub-basin in t Simulation of Reservoir Actions in the L P Model. I = 0 . I = 0 -I = 0 66 C hapter 4 D a t a S o u r c e s an d P r e p a r a t i o n The B a s i c Model The l i n e a r p r o g r a m m i n g m o d el r e q u i r e s t h r e e b a s i c ty p e s of data? th e v a lu e s of t h e r e s o u r c e c o n s t r a i n t s r i g h t hand s i d e s , c ien ts RHS), t h e v a l u e s o f t h e m a t r i x c o e f f i ­ (the a ^ j 's ) , function (the C j's). t h i s model a r e ? (the and t h e v a l u e s i n t h e o b j e c t i v e The m a j o r reso u rce c o n s t r a i n t s for the w ater flow ing in to the the b a sin , i.e., t h e RHS o f t h e w a t e r b a l a n c e e q u a t i o n s , a c r e a g e r e s t r i c ­ tio n s, and t h e v a l u e s o f t h e e x o g e n o u s u s e a c t i v i t i e s . T h es e i n c l u d e minimum i n s t r e a m f l o w f o r f i s h and w i l d l i f e h a b i t a t a nd w a t e r q u a l i t y m a i n t e n a n c e , w a t e r u s e d i n e n e r g y production, and w a t e r f o r m u n i c i p a l u s e . The p r i m a r y a ^ ' s a r e t h e c o n v e y a n c e and f i e l d e f f i c i e n c i e s , r e t u r n f l o w c o e f f i c i e n t s , t h e n e t i r r i g a t i o n r e q u i r e m e n t s f o r t h e crop-, p i n g a c t i v i t i e s and t h o s e f o r l a n d u s e . The r e s t o f t h e a ^ j ' s a r e r e q u i r e d f o r t h e f u n c t i o n i n g of m a t e r i a l b ala n ce e q u a t i o n s and t r a n s f e r a c t i v i t i e s . The m a j o r o b j e c t i v e f u n c t i o n v a l u e s a r e t h e r e t u r n s o v e r v a r i a b l e c o s t s (ROVC) f o r e a c h o f t h e c r o p s grown i n e a c h s u b - b a s i n . 67 H y d ro lo g ic Data S t r e a m f l o w g a u g i n g d a t a on t h e Y e l l o w s t o n e R i v e r was o b t a i n e d f r o m t h e U. S. G e o l o g i c a l S u r v e y ' s c o m p u t e r i z e d d a t a ban k . The y e a r s 1963 t o 1977 w e r e u s e d a s a b a s e p e r i o d f o r t h e c a l i b r a t i o n m o d e l a n d a s t h e b a s i s o f com­ p a ris o n for subsequent a p p lie d runs. The t i m e p e r i o d o f 1 9 6 3 -1 9 7 7 i s n o t i n k e e p i n g w i t h t h e a s s u m p t i o n a b o u t a "ty p ic a l year", in term s of riv e r flow s, sin c e th e average flo w s f o r t h i s p e r io d of y e a r s i s g r e a t e r th a n th e lo n g run average of r i v e r f l o w s .^ The p r o b l e m s i n d e t e r m i n i n g "average" flo w s were d i s c u s s e d i n Chapter I . T his p a r t i c ­ u l a r b a s e p e r i o d was c h o s e n b e c a u s e i t c o i n c i d e d w i t h t h e b a s e p e r i o d o f o t h e r h y d r o l o g i c d a t a and w i t h a v a i l a b l e c r o p p i n g d a t a and t h e r e b y f a c i l i t a t e d t h e c a l i b r a t i o n procedure. The m o d el r e q u i r e s t h a t t h e " i n f l o w s " i n t o t h e t r i b u ­ t a r y and m a i n s t e m s u b —b a s i n s be s p e c i f i e d a s RHS. However, t h e m a t h e m a t i c a l n a t u r e o f l i n e a r p r o g r a m m in g t r e a t s e a c h su b -b a sin as a p o in t in space, o c c u r a t t h e same p o i n t . Thu s, i.e., i n f l o w s and o u t f l o w s in a r e a l i s t i c sense, it is n e c e s s a r y t o t r e a t th e w a te r which flo w s out of a p a r t i c u ­ l a r s u b -b a sin as being a v a i l a b l e fo r d iv e r s io n throughout t h a t s u b - b a s i n and t h e r e f o r e i s t r e a t e d a s i n f l o w . In1 1The 1 9 6 3 -1 9 7 7 a v e r a g e a n n u a l f l o w a t S i d n e y was 10.3 mmaf c o m p a r e d w i t h t h e 1 9 34-1980 a v e r a g e a n n u a l f l o w o f 8.9 mmaf. ^ >' 68 s u b - b a s i n s where v e ry l i t t l e t h e s u b - b a s i n and o u t f l o w , ences, stream flow i s g en erate d w ith in i n t h e a b s e n c e o f human i n f l u ­ i s n e a r l y t h e same a s i n f l o w , t r e a t i n g o u t f l o w a s in flo w i s of l i t t l e consequence. However, i n s u b - b a s i n s where t h e r e i s s u b s t a n t i a l i n t e r n a l r u n o f f , lim itin g speci­ f i e d i n f l o w t o m e a s u r e d s t r e a m i n f l o w would s e r i o u s l y u n d e r e s t i m a t e t h e w a t e r a v a i l a b l e i n t h a t s u b —b a s i n . In c o n ju n c tio n w ith the p rev io u s n o tio n , i t i s im pera­ t i v e t o k e e p i n m in d t h a t t h e h i s t o r i c a l l y m e a s u r e d o u t f l o w f r o m a s u b —b a s i n , on a m o n t h l y b a s i s , a l r e a d y r e f l e c t s . a h i s t o r i c a l p a t t e r n o f d i v e r s i o n and r e t u r n f l o w w h i c h o c c u r r e d i n t h a t s u b —b a s i n . More c o r r e c t l y , i t reflects t h e n e t d i f f e r e n c e o f d i v e r s i o n i n t h a t month and r e t u r n f l o w s t h a t r e t u r n e d i n t h a t m onth. Thus, w h a t i s r e a l l y r e q u i r e d a s a. RHS i s t h e p r i s t i n e f l o w o f t h e r i v e r , t h a t i s , t h e f l o w o f t h e r i v e r i n t h e a b s e n c e o f h u m an i n f l u ­ ences. E s t i m a t e s o f p r i s t i n e r i v e r f l o w s w e r e p r o v i d e d by P h i l F a m e s o f t h e Montana o f f i c e o f S o i l C o n s e r v a t i o n Service, U.S. D e p a r t m e n t o f A g r i c u l t u r e . Conv eyanc e and F i e l d E f f i c i e n c i e s Con veyance and f i e l d e f f i c i e n c i e s f o r t h e n i n e s u b ­ b a s i n s w e r e o b t a i n e d f r o m SCS-USDA (1978). C urrent le v e ls o f c o n v e y a n c e and f i e l d e f f i c i e n c i e s u s e d i n t h e b a s i c m o d el a r e p r e s e n t e d i n T a b l e 2 a l o n g w i t h i n c r e a s e d l e v e l s of e f f i c i e n c i e s f o r th e o t h e r s c e n a r i o s which a r e d i s c u s s e d later in t h i s chapter. 69 Table 2. Model / Scenario C u r r e n t and F u t u r e L e v e l s o f Conveyance and F i e l d E f f i c i e n c i e s . (From SCS-DSDAr 1978) I 2 3 4 Sub - b a s i n 5 , 6 7 8 9 C o n veyance BI (1980) 43 40 50 50 50 50 50 50 32 El (1990) 56 54 59 59 59 59 60 60 44 E2 (2000) 68 67 68 68 68 68 69 69 56 E3 (2010) 81 81 77 77 77 77 79 79 68 F ield BI (1980) 40 40 46 42 45 45 51 50 . 51 (1990) 47 51 51 48 50 50 58 57 53 E2 (2000) 54 61 55 54 54 54 64 64 55 ES (2010) 61 72 60 60 59 59 71 71 . 57 El 70 R e t u r n Flows The d e t e r m i n a t i o n o f t h e g e n e r a l p a t t e r n o f r e t u r n f l o w s was a m o s t d i f f i c u l t e m p i r i c a l t a s k . To t h e e x t e n t t h a t t h e r e h a s b e e n h y d r o l o g i c work t o d e t e r m i n e r e t u r n flow p a t t e r n s , i t h as alw ays been e x tre m e ly s i t e - s p e c i f i c s t u d i e s w h e r e h y d r o l o g i s t s can a c c o u n t f o r f a c t o r s s u c h a s s o i l t y p e s , t o p o g r a p h y , and t h e g e o m o r p h o l o g y o f t h e l o c a l ­ ity , What w as n e e d e d f o r t h i s s t u d y was a g e n e r a l p a t t e r n of r e t u r n flo w s, i.e., a p a t t e r n which r e p r e s e n t s th e a v erag e r e t u r n flo w p a t t e r n over th e range of s o i l ty p es and t o p o g r a p h i c a l f e a t u r e s f o u n d i n a b a s i n . S u b s t a n t i a l t i m e was s p e n t i n c o n j u n c t i o n w i t h t h i s study a tte m p tin g to e m p iric a lly e s tim a te a g e n eral p a tte rn of r e t u r n flow fo r th e Y ellow stone Basin, W hile n o t e n t i r e l y s u c c e s s f u l , work d i d l e a d t o i n d i c a t i o n s o f t h e p a t t e r n of r e t u r n f l o w s found i n t h e Y e llo w sto n e B asin, T h e s e i n d i c a t i o n s t e n d e d t o be c o n f i r m e d by d a t a f r o m t h e Bureau of Reclam ation-USDI ab out r e t u r n flo w p a t t e r n s in t h e S h o s h o n e P r o j e c t i n Wyoming a nd l e d t o t h e a d o p t i o n o f t h e r e t u r n f l o w p a t t e r n shown i n T a b l e 3 f o r u s e i n t h i s stu d y ,^ ^The B u r e a u o f R e c l a m a t i o n - U S D I d a t a i s c o n t a i n e d i n a l e t t e r f r o m t h e Upper M i s s o u r i R e g i o n a l o f f i c e . B u r e a u o f R e c l a m a t i o n - U S D I , B i l l i n g s , M o n t a n a , Au g u st 1 3 , 1982, 71 T able 3. R e t u r n Flow P a t t e r n Used i n t h e LP Model= ------ ------- 1 ----------- R e t u r n flo w occurring: P e r c e n t of t o t a l lo sses: Same month a s d iv er sion 40 1 s t month a f t e r div ersio n 12 2nd month a f t e r d iversion 10.4 3 r d month a f t e r div ersio n 6.4 4 t h month a f t e r div ersio n 3.2 5 month t o t a l -3 72. Minimum Flow R e q u i r e m e n t s The minimum f l o w r e q u i r e m e n t s f o r e a c h a r e a , f o r e a c h o f t h e f i v e m o n th s i n t h e m o d e l , a r e l i s t e d i n T a b l e 4. The v a l u e s u s e d a r e t h e i n s t r e a m r e s e r v a t i o n a m o u n t s g r a n t e d by t h e Bo a rd o f N a t u r a l R e s o u r c e s and C o n s e r ­ v a tio n .4 3 I n o t h e r w o r d s , 72 p e r c e n t o f t h e l o s s e s f r o m c o n v e y a n c e and f i e l d s y s t e m s h a s r e t u r n e d i n 5 m o n th s . The r e m a i n i n g 28 p e r c e n t i s composed o f l o s s e s w h i c h a r e e i t h e r n o n r e c o v e r a b l e o r w i l l r e t u r n a f t e r t h e f i f t h m o n th . ^Minimum f l o w r e q u i r e m e n t s a r e b a s e d on t h e f i n a l i n s t r e a m r e s e r v a t i o n s p u b l i s h e d i n B o r i s and K r u t i l l a (198 0, T a b l e 7 -1 ) e x c e p t f o r t h e B i l l i n g s A r e a w h e r e r e c e n t a d j u s t m e n t s h a v e b e e n made. The v a l u e s f o r t h e B i l l i n g s A r e a a r e c o n t a i n e d i n a l e t t e r from R i c h a r d Moy, C h i e f , W a t e r Management B u r e a u , DNRC, S e p t e m b e r 14, 1982. Table 4. Minimum Instream Flows (acre-feet) I 2 3 4 Sub-basin 5 6 7 8 9 26,000 735,500 May 180,454 1,000 469,309 233,600 755,000 4,600 755,000 June 489,800 3,420 1,093,122 309,300 1,558,000 4,500 1,558,000 July 232,000 I ,400 370,392 221,000 632,000 4,600 632,000 4,000 647,000 August 120,000 381 215,205 â– 172,000 237,000 4,600 237,000 900 164,000 92,508 346 184,878 155,000 267,000 4,500 267,000 500 195,000 September 11,000 1,496,000 '- j tv 73 M u n i c i p a l & Energy R e l a t e d Water Us e At t h e p r e s e n t t i m e , w a t e r u s e d f o r m u n i c i p a l and energy r e l a t e d a c t i v i t i e s i s i n s i g n i f i c a n t r e l a t i v e to t o t a l flow . V a l u e s f o r t h e s e u s e s a r e b a s e d on e s t i m a t e s o f w a t e r u s e i n t h e s e c a t e g o r i e s by B o r i s and K r u t i l l a ( 1 9 8 0 ).5 E n erg y r e q u i r e m e n t s o f 3500 a c r e - f e e t / m o n t h a r e u s e d i n s u b —b a s i n s 5 , 5, and 8 w h i c h e n c o m p a s s p r e s e n t l o c a tio n s of coal r e l a te d in d u s try in the basin. s u b - b a s in s have z e ro energy r e l a t e d w a ter use. A ll other R equire­ m e n t s f o r m u n i c i p a l u s e a r e 500 a c r e - f e e t / m o n t h f o r t h e Upper Y e l l o w s t o n e , 3000 a c r e —f e e t / m o n t h f o r t h e B i l l i n g s Area, 120 a c r e - f e e t / m o n t h f o r t h e M i d - Y e l l o w s t o n e and 140 a c r e - f e e t / m o n t h f o r t h e Lower Y e l l o w s t o n e . The i n c l u s i o n o f b o t h o f t h e s e a c t i v i t i e s i s f a r more i m p o r t a n t m e t h o d ­ o l o g i c a l l y t h a n f o r r e a s o n s o f p r e s e n t s i g n i f i c a n c e as d i s c u s s e d i n C h a p t e r 3. I r r ig a te d Acres I r r i g a t e d a c re a g e fo r each of th e n ine s u b - b a s i n s i s b a s e d on e s t i m a t e s o b t a i n e d f ro m SCS-USDA (1978). T hes e e s t i m a t e s t e n d t o be h i g h e r t h a n a c t u a l m e a s u r e m e n t s o f 5The e n e r g y r e l a t e d w a t e r use v a l u e s i n t h e m o d el a r e b a s e d on e s t i m a t e d c o a l p r o d u c t i o n i n t h e i m m e d i a t e f u t u r e ( a p p r o x i m a t e l y 72 m i l l i o n t o n s ) , s e e B o r i s and K r u t i l l a (1 980, T a b l e 5 - 7 ) . The v a l u e s f o r w a t e r f o r m u n i c i p a l u s e a r e b a s e d on w a t e r r e s e r v a t i o n s g r a n t e d f o r m u n i c p a l u s e and a d e p l e t i o n r a t e o f 50 p e r c e n t o f d i v e r s i o n , s e e B o r i s and K r u t i l l a ( 1 9 8 0 , T a b l e 6 - 8 ) . 74 i r r i g a t e d a c r e s i n any g i v e n y e a r t h a t w o u ld be o b t a i n e d f r o m t h e Montana D e p a r t m e n t o f A g r i c u l t u r e b e c a u s e i t in clu d es a cres th a t are i r r ig a te d in term itten tly .® The h i g h e r e s t i m a t e s w e r e u s e d b e c a u s e i t was f e l t t h a t i t more c o r r e c t l y r e p r e s e n t s th e c u r r e n t l y i r r i g a b l e acrea g e in the basin. A t o t a l o f 5 6 9 ,1 0 0 i r r i g a t e d a c r e s a r e u s e d i n t h e m o d e l. The i r r i g a t e d a c r e s f o r e a c h s u b - b a s i n a r e p r e ­ s e n t e d i n T a b l e 5. I r r i g a t e d Crops The v e c t o r o f a l t e r n a t i v e i r r i g a t e d c r o p s f o r e a c h of t h e n i n e s u b - b a s i n s was c h o s e n , b a s e d on h i s t o r i c a l d a t a , t o be t n o s e p r i n c i p a l c r o p s w h i c h , c o l l e c t i v e l y , w i l l a c c o u n t f o r a p p r o x i m a t e l y 95 p e r c e n t o r more of t h e i r r i ­ g a te d a c r e s in th e county. T h i s was b a s e d on d a t a fro m t h e Montana D e p a r t m e n t o f A g r i c u l t u r e f o r a l l c r o p s e x c e p t i r r i g a t e d p a s t u r e w h i c h was b a s e d on i n f o r m a t i o n f r o m t h e Bureau of Census. The a l t e r n a t i v e c r o p s f o r e a c h o f t h e nine su b -b a sin s a re l i s t e d i n T a b l e 6. I t i s a p p r o p r i a t e t o view th e b a r l e y c ro p p in g a c t i v i t y as a proxy fo r a l l i r r i g a t e d s p r i n g g r a i n s ( o a ts , spring w heat, e t c e te r a ) because of c lo s e s i m i l a r i t i e s of the crops w ith regard to i r r i g a t e d production. For t h e c a l i b r a t i o n m o d e l , w h e r e a h i s t o r i c a l c r o p p i n g p a t t e r n was s p e c i f i e d a s ®For e x a m p l e , t h e 1977 Montana A g r i c u l t u r a l S t a t i s t i c s l i s t s a t o t a l o f 4 34,555 i r r i g a t e d a c r e s i n t h e Y e l l o w s t o n e B asin. 75 Table 5. I r r i g a t e d A c r e a g e s o f t h e Nine S u b - b a s i n s Used . i n t h e LP M odel. (From SCS-USDAr 1978) # Sub-basin Name I r r i g a t e d Acres I Upper Y e l l o w s t o n e 148,208 2 C l a r k s Fo rk 93,532 3 B illin g s 94,490 4 Bighorn 61,110 5 M id-Y ellow stone 58,800 6 Tongue 11,635 7 Kinsey 19,590 8 Powder 11,075 9 Lower Y e l l o w s t o n e 70,660 Basin T o ta l 569,100 . 76 Table 6 . A l t e r n a t i v e Crops f o r t h e N in e S u b - b a s i n s . Upper Y e l l o w s t o n e b a r l e y ? a l f a l f a hay? o t h e r hay? p a stu r e , sugar b e e t s C l a r k s Fork b a r l e y ? a l f a l f a hay? o t h e r hay p a s t u r e ? s u g a r b e e t s ? b ean s? corn s i l a g e B illin g s b a r l e y , a l f a l f a hay? o t h e r h a y , p a s t u r e , sugar b eets? corn (grain) ? c o rn s i l a g e ? b e a n s B ig h o r n b a r l e y ? a l f a l f a hay? o t h e r hay? pasture? sugar b e e ts? corn ( g r a i n ) ? c o rn s i l a g e , b e a n s M id-Y ellow stone b a r l e y ? a l f a l f a hay? o t h e r hay? p astu re? sugar b e e t s , corn ( g r a i n ) ? c o rn s i l a g e ? b e a n s Tongue b a r l e y ? a l f a l f a hay? o t h e r hay pasture? corn s i l a g e Kinsey b a r l e y ? a l f a l f a hay? o t h e r hay? p a s t u r e , sugar b e e ts? corn ( g r a i n ) ? corn s i l a g e ? beans Powder b a r l e y ? a l f a l f a hay? o t h e r hay? pasture? sugar beets? corn (grain) ? co rn s i l a g e Lower Y e l l o w s t o n e b a r l e y ? a l f a l f a hay? o t h e r h a y , p a s t u r e , sugar b e e ts? corn ( g r a i n ) ? corn s i l a g e ? beans 77 a p a r t of th e c a l i b r a t i o n p ro c e d u r e , the b a rle y a c t i v i t y was e x p l i c i t l y a p r o x y and i n c l u d e d a c r e a g e s o f o a t s and s p r i n g wheat in th e c a l c u l a t i o n of the c ro p p in g p a t t e r n . R e t u r n s Over V a r i a b l e C o s t (ROVC) The o b j e c t i v e f u n c t i o n o f t h e model i s t o m a x i m iz e ROVCgS o f t h e d i f f e r e n t c r o p s w h i c h can be g ro w n i n t h e basin. The ROVCs u s e d i n t h i s model a r e b a s e d on m o d i f i e d e n t e r p r i s e b u d g e t s p r e p a r e d by t h e C o o p e r a t i v e E x t e n s i o n S ervice. The m o d i f i e d b u d g e t s a r e l i s t e d i n A p p e n d ix A. S u g a r B e e t and Bean A c r e a g e R e s t r i c t i o n s In a d d i t i o n to th e o v e r a l l acrea g e r e s t r i c t i o n s in a s u b - b a s i n , r e s t r i c t i o n s w e r e p l a c e d on t h e maximum a c r e a g e s o f b e a n s and s u g a r b e e t s . Bo th s u g a r b e e t s and b e a n s a r e s p e c i a l i z e d c r o p s g ro w n u n d e r i n t e n s i v e m an ag em en t and p ro d u ctio n regim es. The l a r g e o b j e c t i v e f u n c t i o n v a l u e s o f t h e s e c r o p s w o u ld r e s u l t i n a b n o r m a l l y h i g h a c r e a g e s i f th e y were l e f t u n r e s t r i c t e d . T h e r e f o r e e x o g e n o u s c on­ s t r a i n t s w e r e u s e d t o r e s t r i c t a c r e a g e s o f t h o s e tw o c r o p s t o more r e a l i s t i c l e v e l s . Sugar b e e t a c re a g e i s l i m i t e d to t h e number o f a c r e s c o n t r a c t e d w i t h t h e b u y er i n t h e Y el­ low stone b asin . T h e r e f o r e s u g a r b e e t a c r e a g e i n t h e model i s l i m i t e d t o t h e a v erag e h i s t o r i c a l a c re a g e s which approx­ i m a t e s t h e number o f c o n t r a c t a c r e s . Beans a r e a l s o l i m i t e d to th e average h i s t o r i c a l acreage in th e basin. 78 Net I r r i g a t i o n R equirem ents The q u a n t i t y o f w a t e r r e q u i r e d f o r e a c h c r o p f o r e a c h month o f t h e g r o w i n g s e a s o n a r e b a s e d on t h e n e t i r r i g a t i o n r e q u i r e m e n t s p u b l i s h e d by t h e SCS-USDA, T his le a v e s i n t a c t t h e SCS a s s u m p t i o n s a b o u t t h e o c c u r r e n c e of e f f e c t i v e r a i n ­ f a l l t h a t are i m p l i c i t in t h a t p u b lic a tio n . Each o f t h e n i n e s u b - b a s i n s h ad t o be c l a s s i f i e d a c c o r d i n g t o c l i m a t i c zon e ( s e e A p p e n d ix B) and t h e n n e t i r r i g a t i o n r e q u i r e m e n t s f o r each c ro p in each a r e a a re d e te rm in e d . These r e q u i r e ­ m e n t s a r e p r e s e n t e d i n A p p e n d ix B. Since i r r i g a t i o n re q u ire m e n ts a re not p u b lis h e d fo r t h e " o t h e r hay" c a t e g o r y , ( g r a s s and n a t i v e hay) i t was a s s u m e d t h a t " o t h e r hay" i s i r r i g a t e d e x a c t l y l i k e a l f a l f a h a y e x c e p t t h a t i r r i g a t i o n s t o p s a t t h e end o f J u l y a f t e r one c u t t i n g h a s b e e n h a r v e s t e d . W hile i t i s u n d o u b ted ly t r u e t h a t some p o r t i o n o f t h i s c a t e g o r y i s i r r i g a t e d a f t e r J u l y , a t l e a s t f o r p a s t u r e , i t a l s o se em s l i k e l y t h a t many " o t h e r h ay" a c r e s a r e i r r i g a t e d f r o m s t r e a m s w h e r e f l o w s a r e r e s t r i c t e d i n l a t e summer. A lte r n a tiv e Scenarios Increased I r r ig a tio n E f f ic ie n c y Scenarios E s t i m a t e s o f c u r r e n t l e v e l s o f c o n v e y a n c e and f i e l d e f f i c i e n c i e s a l o n g w i t h e s t i m a t e s of i n c r e a s e s t o be a c h i e v e d by t h e y e a r 2000 w e r e t a k e n fr o m SCS-USDA (1978). An i n t e r m e d i a t e l e v e l was e x t r a p o l a t e d by t a k i n g t h e 79 c u r r e n t l e v e l plus, h a l f th e d i s t a n c e betw een th e c u r r e n t and y e a r 2000 l e v e l . Also, a h i g h l e v e l was e x t r a p o l a t e d a s b e i n g e q u a l t o t h e y e a r 2000 l e v e l p l u s h a l f t h e d i s t a n c e b e t w e e n t h e c u r r e n t and y e a r 2000 l e v e l s . This provides th re e scen ario s fo r increased i r r i g a t i o n e f f i c ­ iency in a d d it i o n t o th e c u r r e n t v a lu e s. W h i l e t h e r e i s no g u a r a n t e e t h a t t h e s e i n c r e a s e d l e v e l s w i l l be a c h i e v e d a t t h e i m p l i e d t i m e s , a p p r o x i m a t e l y y e a r s 1 9 9 0 , 2 0 0 0 , and 2010, th e y p ro v id e a r e a s o n a b le b a s i s f o r s p e c u l a t i o n ab o u t a t t a i n a b l e l e v e l s from a t e c h n i c a l s t a n d p o in t . The v a l u e s o f c o n v e y a n c e and f i e l d e f f i c i e n c i e s u s e d i n t h e s e s c e ­ n a rio s are l i s t e d i n T a b l e 2. Dry Year S c e n a r i o s V a r i a t i o n in a v a i l a b l e w a te r s u p p l i e s from year to year i s a c r i t i c a l f a c to r a f f e c t i n g the p o s s i b i l i t i e s fo r r i v e r m an a g em en t. Thus, i t was deemed i m p o r t a n t t o i n d i ­ c a te th e im pacts of dry y e a rs . The p h y s i c a l i m p a c t o f d r y y e a r s a r e s i m u l a t e d i n tw o j o i n t a s p e c t s o f t h e m o d e l , d e c r e a s e d r i v e r f l o w s and i n c r e a s e d n e t i r r i g a t i o n r e q u i r e ­ m ents. The i n c r e a s e d n e t i r r i g a t i o n r e q u i r e m e n t s w e r e n e c e s s a r y i n t h i s model b e c a u s e t h e b a s i c model i n c o r ­ p o r a t e s t h e a s s u m p tio n of norm al l e v e l s of e f f e c t i v e r a i n f a l l in d ete rm in in g the n e t i r r i g a t i o n req u ire m e n ts. For p r e s e n t p u r p o s e s , a d j u s t m e n t s w e r e made i n r i v e r f l o w s and r a i n f a l l t h a t w o u ld be i n d i c a t i v e o f t h e i m p a c t s involved. Using a n n u al f lo w s of t h e Y e llo w sto n e R iv er f o r 80 a p e r i o d o f 55 y e a r s a t S i d n e y a s a g u i d e , and a s s u m i n g a normal d i s t r i b u t i o n of r i v e r flo w s , i t is estim ated th a t f l o w s g r e a t e r t h a n 6.9 mmaf w o u l d o c c u r more t h a n 90 p e r ­ c e n t o f t h e t i m e a n d f l o w s g r e a t e r t h a n 8 . 8 7 mmaf w o u l d o c c u r more t h a n 80 p e r c e n t of t h e t i m e . In r e a l i t y , the r i v e r f l o w s do n o t a p p e a r t o be d i s t r i b u t e d n o r m a l l y . A c t u a l f r e q u e n c y c a l c u l a t i o n s f r o m t h e 55 y e a r p e r i o d i n d i ­ c a t e t h a t f lo w s g r e a t e r than or eq u al to t h e s p e c i f i e d f l o w s w o u l d o c c u r a b o u t 75 a n d 54 p e r c e n t o f t h e t i m e resp ectiv ely . In o t h e r words, flow used th e s e s c e n a r i o s flow s l e s s than th e " d r i e s t 0 (6.9 mmaf) a c t u a l l y o c c u r r e d 46 p e r c e n t of th e tim e in t h e h i s t o r i c a l p e rio d . U s i n g d a t a p r o v i d e d by C a p r i o , S n y d e r , and G r u n w a ld (1 9 8 0 ), r e d u c t i o n s i n r a i n f a l l w h i c h would o c c u r 90 and 80 p e r c e n t of th e tim e were a l s o e s t i m a t e d . The e s t i m a t e s o f th e n e t i r r i g a t i o n r e q u ire m e n ts were then a d ju s te d a c c o rd in g t o th e lo w e r l e v e l s of r a i n f a l l . The a d j u s t m e n t s i n r i v e r f l o w and r a i n f a l l w e r e g e n e r ­ a l i z e d i n t o c o n s t a n t p e r c e n t a g e c h a n g e s i n r i v e r f l o w s and n e t i r r i g a t i o n r e q u i r e m e n t s and a p p l i e d p r o p o r t i o n a l l y i n a l l sub-basins. The f i r s t d r y y e a r s c e n a r i o i s b a s e d on d e c r e a s e s i n r i v e r f l o w s o f 14 p e r c e n t a n d i n c r e a s e s i n n e t i r r i g a t i o n r e q u i r e m e n t s o f 13 p e r c e n t . The s e c o n d d r y y e a r s c e n a r i o i s b a s e d on r i v e r f l o w . d e c r e a s e s o f 33 p e r c e n t a n d i n c r e a s e s i n n e t i r r i g a t i o n r e q u i r e m e n t s o f 21 p e r c e n t . 81 I n c r e a s e d L evel of A g r i c u l t u r a l P r i c e s Values a s s o c i a t e d w ith w ater fo r i r r i g a t e d a g r i c u l ­ t u r a l u s e a r e i m p u t e d v a l u e s d e r i v e d fro m t h e v a l u e o f t h e a g r i c u l t u r a l p r o d u c ts produced w ith w ater. Thus, a ch an g e i n th e l e v e l of p r i c e s f o r a g r i c u l t u r a l p r o d u c ts w i l l c h a n g e t h e v a l u e o f w a t e r and w i l l have e c o n o m ic i m p a c t s p e r t i n e n t t o w a t e r m anagem ent p o l i c i e s i f w a t e r i s a s c a r c e resource. A d j u s t m e n t s i n p r i c e s w e r e made b a s e d on r a t i o s o f t h e p r i c e s p a i d and p r i c e s r e c i e v e d i n d i c e s . For exam­ p l e , a s an a p p r o x i m a t i o n t o t h e l e v e l o f r e t u r n s t o a g r i c u l t u r e w h i c h p r e v a i l e d i n 1973, t h e r a t i o o f t h e 1973 p r i c e s r e c i e v e d and p r i c e s p a i d i n d i c e s w e r e c o m p a r e d t o t h e 19 80 r a t i o o f t h e s e i n d i c e s a n d t h e n t h e a d j u s t m e n t s o f t h e p r i c e s r e c i e v e d i n t h e 1980 b u d g e t s i n o r d e r t o a p p r o x ­ i m a t e t h e 1974 r a t i o can be c a l c u l a t e d . . T h i s p r o c e d u r e r e s u l t e d i n i n c r e a s e d p r i c e s r e c i e v e d i n t h e 1980 b u d g e t s o f a b o u t 42 p e r c e n t . T h i s was u s e d a s t h e f i r s t h i g h e r a g r ic u ltu r a l p ric e s scenario. A second s c e n a r i o based l o o s e l y on p r o j e c t i o n s of t h e p r i c e s p a i d and r e c i e v e d i n d i c e s w h i c h w o u ld e x i s t i f t h e r e was an i n c r e a s e i n t h e p r i c e s o f a g r i c u l t u r a l c r o p s i n t h e 1980 b u d g e t s o f a b o u t 70 p e r c e n t . Indexing th e p r i c e s re c ie v e d alone a ls o r e s u l t s in c h a n g e s i n th e r e l a t i v e v a lu e s of c r o p s as w e l l , w hich i s t o be e x p e c t e d . How ever, i t i s d e s ir a b le in t h i s a n a ly s is t o look a t th e im p act of h ig h e r l e v e l s of a g r i c u l t u r a l 82 re tu rn s c e t e r i s p e rIbus » i.e ., including the r e la tiv e constant. T herefore, holding e v ery th in g e l s e , r a n k i n g o f t h e ROVCs o f t h e c r o p s th e i n c r e a s e s in p r i c e s r e c e i v e d were t r a n s l a t e d i n t o c o n s t a n t p e r c e n t a g e c h a n g e s i n t h e ROVC1s and a p p l i e d t o a l l c r o p s . The tw o s c e n a r i o s r e s u l t e d i n p r o p o r t i o n a t e i n c r e a s e s i n ROVCs o f 78 and 134 p e r c e n t resp ectiv ely . In c rea sed I r r i g a t e d Acreage S c e n a r io s Three s c e n a r i o s of a d d i t i o n a l i r r i g a t e d a c r e a g e were a ls o developed. The f i r s t tw o s c e n a r i o s a r e b a s e d on p r o ­ j e c t i o n s of e c o n o m ic a lly f e a s i b l e a d d i t i o n a l a c re a g e a t a "low" and " i n t e r m e d i a t e " l e v e l o f f u t u r e d e v e l o p m e n t done by t h e DNRC (1977d). tio n al i r r i g a t e d a c r e a g e s o f 7 9 ,1 6 0 and 1 58,310 a c r e s resp ectiv ely . increase lev el T h ese two s c e n a r i o s r e p r e s e n t a d d i ­ A th ir d scenario, w h i c h r e p r e s e n t s an i n i r r i g a t e d a c r e a g e e v e n beyond t h e DNRC "high" (237,4 80 a c r e s ) , i s b a s e d on t h e t o t a l number o f a d d i t i o n a l a c r e s f o r w h i c h w a t e r r e s e r v a t i o n s h a v e be en granted, 2 65,881 a c r e s . In each of th e s e s c e n a r i o s th e a d d itio n a l a c re s a re d i s t r i b u t e d throughout th e b a sin according to the d i s t r i b u t i o n of c u r r e n t l y i r r i g a t e d a c r e s . 83 C hapter 5 R esults The r e s u l t s o f u s i n g t h e LP m o d e l t o g e n e r a t e a s o l u ­ t i o n f o r t h e b a s i c Y e l l o w s t o n e R i v e r B a s i n m od el and f o r a s e r i e s of a lt e r n a t iv e scen a rio s are presented in t h i s chapter. The a l t e r n a t i v e s c e n a r i o s i n v o l v e f a c t o r s w h ic h a f f e c t e i t h e r p h y s i c a l or e c o n o m i c v a r i a b l e s w h i c h have i m p l i c a t i o n s f o r w a t e r management p o l i c i e s . Each o f t h e s c e n a r i o s i s b a s e d on a v a r i a t i o n o f one major co m p on en t o f t h e m od el w h i l e t h e r e m a i n i n g c o m p o n e n ts a r e h e l d c o n s t a n t . The p u r p o s e i s t o a n a l y z e t h e i m p a c t o f c h a n g e s o f t h a t co m p on en t on t h e r e s t o f t h e s y s t e m . The f o l l o w i n g i s a s u m m a r y o f t h e b a s i c m o d e l a n d t h e s c e n a r i o s w h i c h w e r e d e v e l o p e d i n C h a p t e r s 3 and 4 and t h e n o t a t i o n used in p r e s e n t i n g t h e r e s u l t s . The B a s i c Model BI T h i s i s . t h e m odel o f t h e Y e l l o w s t o n e River B asin a t the p r e s e n t tim e. It i n c o r p o r a t e s c u r r e n t l e v e l s of conveyance and f i e l d e f f i c i e n c i e s ( r e p r e s e n t i n g a b a s i n - w i d e i r r i g a t i o n e f f i c i e n c y o f 19 p ercen t), cu rren tly irrig a te d acres, r e t u r n s o v e r v a r i a b l e c o s t s b a s e d , o n 1980 c ro p b u d g e ts , s p e c i f i e d r e t u r n flow p a t t e r n , c u r r e n t minimum i n s t r e a m f l o w r e q u i r e m e n t s , and a d j u s t e d r i v e r f l o w v a l u e s fr o m t h e c a l i b r a t i o n p h a s e . 84 Increased I r r ig a tio n E ffic ie n c y Scenarios El Conve yanc e and f i e l d e f f i c i e n c i e s a r e i n c r e a s e d a b o u t 43 p e r c e n t o v e r t h e b a s i c m odel l e v e l s t o a b a s i n - w i d e i r r i g a t i o n e f f i c i e n c y 28 p e r c e n t . E2 Conveyance and f i e l d e f f i c i e n c i e s a r e i n c r e a s e d a b o u t 92 p e r c e n t o v e r t h e b a s i c m odel l e v e l s t o a b a s i n - w i d e i r r i g a t i o n e f f i c i e n c y o f 37 p e r c e n t . T his l e v e l of e f f i c i e n c y i s t h a t p r o j e c t e d by t h e SCS t o be a c h i e v e d f o r t h e y e a r 2000. E3 Conveyanc e and f i e l d e f f i c i e n c i e s a r e i n c r e a s e d a b o u t 150 p e r c e n t o v e r t h e b a s i c m o d el l e v e l s t o a b a s i n - w i d e i r r i g a t i o n e f f i c i e n c y o f 48.5 p e r c e n t . Dry Year S c e n a r i o s ( c o m p a red t o t h e b a s i c m odel w h i c h i s b a s e d on an a n n u a l f l o w a t S i d n e y o f 10.2 mmaf, t h e a v e r a g e f l o w f o r t h e 1 9 6 3 -1 9 7 7 p e r i o d . ) Dl S p e c i f i e d r i v e r f l o w s a r e d e c r e a s e d 14 p e r c e n t and n e t i r r i g a t i o n r e q u i r e m e n t s i n c r e a s e d 13 p e r c e n t f r o m t h e b a s i c m o d e l . T h i s r e p r e s e n t s an a n n u a l f l o w of 8 . 8 7 mmaf a t S i d n e y w h i c h i s o n l y s l i g h t l y b e lo w t h e 1 9 34-1980 h i s t o r i c a l a v e r a g e o f 8.9 mmaf. F l o w s l o w e r t h a n t h i s l e v e l o c c u r r e d h i s t o r i c a l l y 23 o u t of 55 y e a r s i n t h e 1 9 2 4 -1 9 8 0 p e r i o d . D2 S p e c i f i e d r i v e r f l o w s a r e d e c r e a s e d 33 p e r c e n t and n e t i r r i g a t i o n r e q u i r e m e n t s i n c r e a s e d 21 p e r c e n t f r o m t h e b a s i c m o d e l . T h i s r e p r e s e n t s an a n n u a l f l o w a t S i d n e y o f 6.9 mmaf. F l o w s l o w e r t h a n t h i s l e v e l o c c u r r e d h i s t o r i c a l l y 13 o u t o f 55 y e a r s i n t h e 1924 -1 9 8 0 p e r i o d . I n c r e a s e d I r r i g a t e d Acreage S c e n a r io s Al I r r i g a t e d a crea g e of th e b a s in i s i n c r e a s e d by 7 9 ,1 6 0 a c r e s , a b o u t 14 p e r c e n t over th e b a s i c model. A2 I r r i g a t e d a c re a g e of th e b a s in i s i n c r e a s e d by 15 8 ,3 1 0 a c r e s , a b o u t 28 p e r c e n t o v e r t h e b a s i c m o d e l. 85 A3 I r r i g a t e d a c re a g e of th e b a s in i s i n c r e a s e d by 2 6 5 ,8 8 1 a c r e s , a b o u t 47 p e rc e n t over th e b a s i c model„ Increased A g ric u ltu ra l P ric es S cenarios Pl R e tu rn s over v a r i a b l e c o s t s of a l l c ro p s a r e i n c r e a s e d 78 p e r c e n t o v e r t h e b a s i c m od el l e v e l s . T h i s a p p r o x i m a t e s t h e l e v e l o f ROVC's f o r a g r i c u l t u r a l p r o d u c t s i n 1973. P2 R eturns over v a r i a b l e c o s ts of a l l crops a r e i n c r e a s e d 134 p e r c e n t o v e r t h e b a s i c m odel l e v e l s . C a l i b r a t i n g The Model The Y e l l o w s t o n e R i v e r B a s i n i s f e d by a m u l t i t u d e o f ungauged, s t r e a m s w h i c h c o n t r i b u t e t o s t r e a m f l o w a s s t r e a m augm entation. A l s o , r i v e r f l o w i s s u b j e c t t o l o s s e s due t o d e e p p e r c o l a t i o n f r o m t h e r i v e r b ed and e v a p o r a t i o n fro m the stream su rfa c e . N et s t r e a m a u g m e n t a t i o n (NSA) i s d e f i n e d a s t h e sum o f s t r e a m a u g m e n t a t i o n and s t r e a m lo sses, f o r a p a r t i c u l a r r e a c h o f r i v e r and t i m e i n t e r v a l . Net s t r e a m a u g m e n t a t i o n can be e i t h e r p o s i t i v e or n e g a t i v e d e p e n d i n g on w h e t h e r t h e l o s s e s o u t w e i g h t h e a u g m e n t a t i o n s in a given tim e i n t e r v a l . I n s p e c t i o n o f g a u g i n g d a t a shows t h a t i n w i n t e r m o n th s a c t u a l m e a s u r e d o u t f l o w s f r o m some a re a s a re l e s s than in flo w s i n d ic a t i n g t h a t n e t stream a u g m e n t a t i o n c a n become n e g a t i v e a t c e r t a i n t i m e s . N e i t h e r s t r e a m a u g m e n t a t i o n s o r s t r e a m l o s s e s have been e m p i r i c a l l y m easured along th e Y e llo w sto n e R iv er. b a lan ce e q u a tio n of r i v e r flow for a p a r t i c u l a r tim e A 86 i n t e r v a l t h a t a c c o u n t s f o r n e t s t r e a m a u g m e n t a t i o n and re tu rn flow s i s O utflow - ( I n f l o w + D i v e r s i o n ) = (NSA + R e t u r n f lo w ) R e a s o n a b l e e s t i m a t e s o f t h e q u a n t i t y (NSA + R e t u r n flo w ) c a n be o b t a i n e d u s i n g o b s e r v e d v a l u e s o f i n f l o w and o u t f l o w and c a l c u l a t e d d i v e r s i o n s , irrig a tio n efficien cies, w h i c h a r e b a s e d on e s t i m a t e d n e t i r r i g a t i o n r e q u i r e m e n t s , and h i s t o r i c a l l y observed cropping p a tt e r n s . However, i t is n o t p o s s i b l e t o s e p a r a t e n e t s t r e a m a u g m e n t a t i o n s and r e t u r n f l o w s i n t o t h e i r r e s p e c t i v e m a g n i t u d e s u n l e s s one or t h e o t h e r i s known. In t h i s c ase , n e t stream augm entation w a s t r e a t e d a s a n u n k n o w n v a r i a b l e t o be e s t i m a t e d a s a r e s i d u a l when t h e r e t u r n f l o w p a t t e r n was s p e c i f i e d . The r e t u r n f l o w c o e f f i c i e n t s w e r e b a s e d on r e t u r n f l o w p a t t e r n s estim ate d a t otner lo c a tio n s. I n some o f t h e s u b - b a s i n s , s u c h a s t h e U p p e r Y e l l o w ­ s t o n e and t h e C l a r k s F o r k , i t a p p e a r s t h a t n e t s t r e a m a u g m e n t a t i o n i s p o s i t i v e and s i g n i f i c a n t i n t h e summer. In t h e l o w e r p o r t i o n o f t h e b a s i n h o w e v e r , n e t s t r e a m augmen­ t a t i o n may be e i t h e r p o s i t i v e , n e g a t i v e or n e a r l y z e r o d u r i n g t h e summer m o n t h s . The c a l i b r a t i o n p r o c e s s makes an e s tim a te of n e t stream augm entation during th e c a l i b r a t i o n p h a s e , and t h e r e a f t e r i t i s t a c i t l y a ssu m e d t h a t n e t s t r e a m augm entation s ta y s c o n s ta n t throughout a l l of th e sc e n a rio s 87 e x c e p t th e d ry y e a r s c e n a r i o s where n e t s tre a m a u g m e n ta tio n i s a d j u s t e d downward p r o p o r t i o n a t e l y w i t h r i v e r f l o w s . The LP model was c a l i b r a t e d t o a v e r a g e l e v e l s o f r i v e r flo w f o r t h e p e r i o d 1963-1977. th e f o l l o w i n g were s p e c i f i e d ? I n c a l i b r a t i n g t h e m o d e l, th e r e t u r n flow p a t t e r n , the n e t i r r i g a t i o n re q u ire m e n ts fo r c ro p s, th e l e v e l s of con­ v e y a n c e and f i e l d e f f i c i e n c i e s and a c r o p p i n g p a t t e r n (an a v e r a g e c r o p p i n g p a t t e r n f o r t h e y e a r s 1 9 5 9 -1 9 7 8 was u s e d for c a lib ra tio n ). Then e s t i m a t e s o f n e t s t r e a m a u g m e n t a ­ t i o n w e r e a d j u s t e d so t h a t t h e m o d el g e n e r a t e d r i v e r f l o w s which c o rre sp o n d e d t o th e a v erag e m easured flo w s of th e r i v e r f o r t h e 1 9 6 3 —1977 p e r i o d . C a l i b r a t i o n was b a s e d on USGS m e a s u r e m e n t s o f r i v e r f l o w s a t t h r e e c h e c k p o i n t s on th e m ainstem ; B i l l i n g s , M i l e s C i t y , and S i d n e y . The a v e r ­ a g e a n n u a l f l o w o f t h e r i v e r a t S i d n e y f o r t h i s p e r i o d was 10.2 mmaf. The c a l i b r a t i o n p r o c e s s a c c o m p l i s h e d tw o p u r ­ poses? f i r s t , i t was u se d t o a d j u s t t h e m odel t o a c c o u n t f o r n e t s t r e a m a u g m e n t a t i o n and s e c o n d , i t was u s e d t o im p r o v e t h e i n t e r n a l c o n s i s t e n c y o f t h e m o d el. R e s u l t s o f t h e c a l i b r a t i o n r u n a r e r e a s o n a b l e when c o m p a r e d t o v a l u e s a p p r o x i m a t e d by t h e SCS-USDA (1978) i n th e Y ellow stone Basin. For e x am p le ? t h e a v e r a g e d i v e r s i o n p e r a c r e o f t h e c a l i b r a t e d model i s 6.63 a c r e - f e e t p e r a c r e ( a f / a c r e ) , a b o u t 92 p e r c e n t o f t h e SCS v a l u e o f 7.22 af/acre? c r o p i r r i g a t i o n r e q u i r e m e n t s a r e a b o u t 1.29 af/acre, a b o u t 88 p e r c e n t o f t h e SCS v a l u e o f 1.46 a f / a c r e ? 88 and r e t u r n f l o w s f o r t h e May t o S e p t e m b e r i n t e r v a l a r e a b o u t 3.23 a f / a c r e , c o m p a r e d t o t h e SCS v a l u e o f 3.94 af/acre. C e rta in p a ra m eters s p e c if ie d during th e c a l i b r a t i o n p r o c e s s w e r e m o d i f i e d i n o r d e r t o r u n t h e b a s i c model and the subsequent scen ario s. The c r o p p i n g p a t t e r n was r e l e a s e d i n o r d e r t o a l l o w t h e LP m o d e l t o s e l e c t t h e c r o p r o t a t i o n t h a t w o u ld m a x i m i z e r e t u r n s t o a g r i c u l t u r e according to the o b je c tiv e fu n c tio n . I r r ig a te d acreage c o n s t r a i n t s were changed from t h e h i s t o r i c a l l e v e l s used in the c a l i b r a t i o n p ro cess to c u rre n t values. minimum i n s t r e a m f l o w r e s t r i c t i o n s , In a d d itio n , which were n o t in p la c e d u r i n g t h e h i s t o r i c a l c a l i b r a t i o n p e r i o d , w e r e im p o s ed on t h e model. R e s u l t s o f t h e B a s i c Model The r e s u l t s o f t h e b a s i c m o d e l and t h e s c e n a r i o s a r e p r e s e n te d in a s e r i e s o f t a b l e s which are l i s t e d below . Table 7. B a s i n - w i d e Summary o f t h e B a s i c Model Table 8. T o t a l D i v e r s i o n s and R e t u r n F lo w s . T able 9. D i v e r s i o n s by S u b - b a s i n . T able 10. R e t u r n Flows by S u b - b a s i n . T ab le 11. B asin-w ide Cropping P a t t e r n s . T able 12. R eturns to A g r ic u ltu r e . T ab le 13. Shadow P r i c e s o f W a t e r . T a b l e 14 . Shadow P r i c e s o f I r r i g a t e d A c r e s . 89 A summary o f t h e b a s i n - w i d e r e s u l t s o f t h e b a s i c m odel a r e p r e s e n t e d i n T a b l e 7. D i v e r s i o n s and r e t u r n f l o w s f o r t h e i n d i v i d u a l s u b - b a s i n s a r e p r e s e n t e d i n T a b l e s 9 and 10. R eturns to a g r i c u l t u r e fo r the in d iv id u a l s u b -b a sin s in the b a s i c m o d e l a r e p r e s e n t e d i n t h e f i r s t c o lu m n o f T a b l e 12. To t h e e x t e n t t h a t w a t e r i s s c a r c e i n t h e b a s i n , t h e m o d e l w i l l r e f l e c t e c o n o m ic s c a r c i t y a s a n o n z e r o shadow p r i c e . The s h a d o w p r i c e s f o r w a t e r i n t h e b a s i c m o d e l , by t i m e i n t e r v a l and s u b - b a s i n , a r e l i s t e d T a b l e 13. i n t h e f i r s t c o lu m n o f T h u s, t h e m odel d e t e c t s e c o n o m ic s c a r c i t y o f w a t e r i n A u g u s t ( t i m e i n t e r v a l 3) i n s u b - b a s i n s I , and 8. 2 , 3, The v a l u e o f t h e shadow p r i c e s r e p r e s e n t t h e v a l u e o f an a d d i t i o n a l a c r e - f o o t o f w a t e r a t t h e m a r g i n , L e., w h a t on e a d d i t i o n a l a c r e - f o o t o f w a t e r w o u ld c o n t r i b u t e t o th e value of th e o b je c tiv e fu n c tio n . Table 7. B a s i n - w i d e Summary o f t h e B a s i c Model ( B i ) . T otal P e r A cre D iversion (ac-ft) 4,119,824 'S b CM R e t u r n Flow (ac-ft) 1,976,081 3.47 111,640,157 196.17 R eturns to A g ric u ltu re Table 8. Total Diversions and Return Flows (May to September in Acre-feet). B asic M odel BI Increased Ir rig a tio n E ffic ie n cy S c e n ario s E2 El D ry Y e a r S c e n ario s E3 Dl D2 Al Increased I r r ig a tio n A creage S c e n ario s A2 A3 D iv ersio n s 4 ,1 1 9 ,8 2 4 2 ,9 5 9 ,9 4 0 2 ,2 2 6 ,4 7 8 1 ,7 1 3 ,7 2 7 4 ,4 2 3 ,7 0 1 3 ,3 9 1 ,6 7 0 4 ,6 0 8 ,2 9 6 5 ,0 9 6 ,0 7 6 5 ,7 5 8 ,7 1 7 R e tu rn Flow s 1 ,9 7 6 ,0 8 1 1 ,2 5 6 ,9 2 6 818,641 5 1 8 ,4 9 6 2 ,1 4 1 ,6 9 3 1 ,6 1 8 ,5 1 4 2 ,2 1 7 ,4 3 3 2 ,4 5 9 ,4 2 7 2 ,7 8 8 ,1 8 7 Table 9. S u b -b asin Diversions by Sub-basin B asic M odel BI El (May to September in Acre-feet). Increased Ir rig a tio n E ffic ie n cy S c e n ario s E2 D ry Y e ar S c e n ario s E3 Dl D2 Al Increased I r r ig a tio n A creage S c e n ario s A2 A3 i 1 ,2 4 8 ,4 6 4 815 ,8 6 4 5 8 4 ,7 9 3 4 3 4 ,6 0 0 1 ,4 1 1 ,1 9 5 947 ,9 5 8 1 ,4 2 1 ,9 7 4 1 ,5 9 5 ,4 6 0 1 ,8 3 1 ,2 3 7 2 678,0 7 4 539,701 363,675 254,8 6 0 691,5 2 3 104,1 9 8 6 9 3 ,5 4 2 7 7 5 ,4 8 5 886 ,8 4 9 3 648,6 0 9 47 2 ,5 0 1 3 9 8 ,8 7 7 3 2 2 ,9 0 1 577,0 7 8 5 8 3 ,8 4 4 739 ,6 7 7 7 6 3 ,6 2 7 7 9 6 ,1 7 7 4 4 6 3 ,8 8 7 343,984 265,2 9 5 210,8 5 8 5 2 4 ,3 5 1 561 ,2 5 9 529 ,2 2 7 594,560 683,350 5 340,4 0 3 2 5 9 ,6 2 9 2 0 8 ,5 8 0 168,5 9 1 3 8 4 ,7 5 5 4 1 2 ,0 2 1 3 8 6,065 4 3 1 ,7 1 6 493 ,4 8 5 6 6 5 ,155 4 9 ,6 9 5 3 9 ,9 2 4 3 2 ,269 7 3 ,638 7 8 ,861 74 ,4 6 4 8 3 ,777 9 6 ,4 2 8 7 1 0 0 ,4 3 9 7 3 ,5 9 8 5 7 ,9 9 7 4 5 ,6 6 4 1 1 3 ,5 2 7 121,5 7 3 1 14,131 1 2 7,819 146,423 8 5 5 ,2 2 0 4 1 ,3 5 6 3 2 ,0 3 0 2 5 ,216 6 0 ,2 4 4 6 2 ,3 8 3 61,7 3 7 6 8 ,2 5 3 77 ,1 1 2 9 519,5 7 3 3 6 3 ,6 1 2 275,3 0 7 2 1 8 .7 6 8 5 8 7 ,3 9 0 5 1 9 ,5 7 3 5 87,479 655,3 7 9 747,656 Table 10. S u b -b asin Return Flows by Sub-basin (May to Septernber in Acre-feet). B asic M odel BI El In creased Ir rig a tio n E ffic ie n cy S cen ario s E2 D ry Y e ar S cen ario s E3 Dl D2 Al Increased Ir rig a tio n A creage S cen ario s A2 A3 i 6 1 4 ,7 6 7 3 5 7 ,7 1 1 2 2 0 ,1 7 7 1 3 0 ,8 0 2 6 9 4 ,8 1 7 5 1 2 ,1 9 2 700,2 3 8 7 85,697 901 ,8 4 1 2 3 6 0 ,7 2 4 232 ,9 6 1 127,504 6 2 ,9 7 1 3 7 7 ,2 6 8 5 0 ,3 9 1 3 7 9 ,2 0 2 4 2 4 ,7 4 0 4 8 6 ,6 2 9 3 2 9 4 ,8 7 9 196,299 1 4 7 ,0 4 2 1 0 2 ,5 7 0 271,9 5 8 253,9 4 1 3 3 6 ,6 8 8 3 5 2,097 373 ,0 3 8 4 2 1 6 ,5 9 8 145,693 9 9 ,198 6 7 ,0 5 2 244,854 262,0 6 6 247 ,3 0 1 2 7 8 ,0 0 0 319 ,7 2 4 5 1 4 8 ,7 5 9 103 ,2 0 6 7 4 ,4 1 2 5 1 ,8 7 6 168,160 1 8 0 ,0 3 7 168,694 1 8 8 ,6 2 7 2 1 5 ,5 9 5 6 2 8 ,4 4 8 2 1 ,0 7 6 1 4 ,2 3 2 9 ,9 2 0 3 2 ,1 5 4 3 4 ,4 2 6 3 2 ,511 36 ,5 7 7 4 2 ,1 0 0 7 4 2 ,1 6 3 2 7 ,035 1 8 ,245 1 1 ,2 9 7 4 7 ,6 6 3 5 1 ,030 4 7 ,9 1 0 5 3 ,6 5 5 6 1 ,4 6 4 8 2 3 ,8 0 2 1 5 ,2 4 2 1 0 ,0 7 4 6,237 2 6 ,7 4 4 2 8 ,4 9 0 2 6 ,9 2 8 30 ,0 5 5 3 4 ,3 0 5 9 2 4 5 ,9 4 1 157 ,7 0 3 1 07,757 7 5 ,7 7 1 278,075 245,9 4 1 277,9 6 1 3 0 9,979 3 5 3 ,4 9 1 Table 11. Basin-wide Cropping Patterns C rop B asic M odel 0 B arley A lfa lfa H ay O t h e r Hay P astu re 2 9 2 ,9 6 3 Increased Ir rig a tio n E ffic ie n cy S cen ario s El E 2 .E 3 0 3 8 4 ,1 5 6 0 3 5 8 ,7 6 9 (acres). D2 A d d itio n al Ir r ig a te d A creage S cen ario s Al A2 A3 0 0 0 0 0 227,3 3 9 6 0 ,5 8 4 317 ,1 9 9 3 3 5 ,4 8 2 3 60,330 D ry Y ear S c e n ario s Dl 6 5 ,8 0 6 0 0 8 3 ,2 4 4 133,0 9 7 9 6 ,226 109,207 1 2 6 ,8 4 9 0 0 0 0 0 0 0 0 Suqar B eets 5 7 ,9 7 5 5 7 ,9 7 5 5 7 ,975 5 7 ,9 7 5 5 7 ,9 7 5 5 7 ,9 7 5 5 7 ,975 5 7 ,9 7 5 C orn S i l a g e 138,2 6 4 1 3 9 ,8 7 8 139,8 7 8 1 3 5 ,9 9 3 210,135 160 ,9 8 5 1 8 3 ,7 0 3 214,5 2 7 1 2 ,4 7 8 1 2 ,4 7 8 1 2 ,4 7 8 1 2 ,4 7 8 1 2 ,478 1 2 ,4 7 8 1 2 ,4 7 8 1 2 ,4 7 8 1 ,614 1 0 ,6 1 3 5 2 ,0 7 1 5 ,997 3 ,398 2 8 ,567 6 2 ,7 7 3 T otal Irrig a te d A creage 569 ,1 0 0 569,1 0 0 5 6 9 ,1 0 0 4 8 0 ,2 6 6 6 4 8 ,2 6 1 7 2 7,412 8 3 4 ,9 3 2 B eans C orn S la c k 0 5 6 9 ,1 0 0 8 8 ,8 3 4 Table 12. S u b -b asin Returns to Agriculture (dollars). B asic Model BI In c re a s e d I r r i g a t i o n E f f ic ie n c y S e c e n a rio s El E2,E3 Dry Y ear S c e n a rio s Dl D2 Al In c re a se d I r r i g a t i o n A creage S c e n a rio s A2 A3 In c re a se d A g r ic u ltu r a l P r ic e s S c e n a rio s Pl P2 • I 31 ,0 2 2 ,8 4 0 31,022,840 3 1 ,022,840 31,022,840 13,186,888 35,318,921 39,614,376 45,452,137 55,220,744 2 12,110,118 2 0 ,351,661 20,351,661 9 ,9 2 6 ,1 8 3 2 ,9 7 6 ,1 4 1 11,010,050 12,093,834 13,566,764 21.555,877 28,337,937 3 2 1 ,132,004 19,967,652 21,132,004 1 5 ,845,518 18,825,321 23,817,986 23,937,981 2 4 ,101,125 37,615,017 49,449,038 72,593,712 4 1 3 ,425,043 13,425,043 13,425,043 1 3 ,425,043 13,425,043 15,192,986 16,960,720 19,363,203 23,896,609 31,414,700 5 11 ,3 7 9 ,7 6 5 11,379,765 11,379,765 11,379,765 11,379,765 12,835,091 14,290,060 16,258,694 20,255,761 26,628,493 4,859,241 6 2 ,0 7 6 ,6 1 5 2 ,0 7 6 ,6 1 5 2 ,0 7 6 ,6 1 5 2 ,0 7 6 ,6 1 5 2,07 6 ,6 1 5 2,373,249 2,670,061 3,073,247 3,696,323 7 3 ,7 8 5 ,6 1 9 3 ,7 85,619 3,785,619 3 ,7 8 5 ,6 1 9 3,785,619 4,280,187 4,77 4 ,5 7 7 5,446,554 6,738,329 8,85 8 ,2 9 7 8 1 ,9 0 0 ,1 7 5 2 ,0 2 8 ,4 2 3 2,02 8 ,4 2 3 1,719,721 1,551,902 2,068,092 2,236,009 2,46 4 ,1 5 1 3,382,295 4,446,386 9 14 ,8 0 7 ,9 7 8 14,807,978 14,807,978 14,807,978 14,807,978 16,574,038 18,339,919 20,739,761 26,357,984 34.650,520 111,640,157 118,845,596 120,009,948 103,989,282 82,105,272 123,470,600 134,917,537 150,465,536 198,718,939 261.238,324 94 Table 13. Sub­ b a s in i Time In te rv a l May June J u ly Auqust Septem ber Shadow Prices of Water In c re a se d Irrig a tio n E f f ic ie n c y S c e n a rio s* Cl B asic Model BI p ry Year S c e n a rio s Dl J u ly A ugust Septem ber J u ly A ugust ‘Septem ber 59.50 9 4 .9 8 62.26 May June J u ly A ugust Septem ber 6 May June J u ly A ugust Septem ber In c re a se d A g r ic u ltu r a l P r ic e s S c e n a rio s Pl p; 1 .0 0 57.58 1.00 71.68 71.68 71.53 1.00 114.24 153.54 114.24 153.54 114.24 153.54 1 .0 0 69.82 1.00 59 .5 0 9 4 .9 8 62.26 57.88 62.26 1.00 69.82 1.00 57.88 5 9 .5 0 9 4 .9 0 J u ly August Septem ber 5 A3 1 .00 May 4 Al 1.00 May 3 D2 A d d itio n a l Irrig a te d A creage S c e n a rio s A2 69.82 May 2 (dollars). 1.00 71.68 71.68 71.53 1.00 71.68 1.00 71.53 71.68 1.00 1.00 1 .0 0 1.00 1 .0 0 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1 .0 0 1.00 1.00 1.00 1 .0 0 1 .0 0 1 .0 0 May 7 J u ly August . Septem ber May 8 J u ly A uqust Septem ber 5 7 .3 7 . 50.40 1.00 46.72 1.00 57.37 57.37 57.30 May 9 June J u ly August Septem ber 1.00 •E2 and E3 scenarios were not included in this table because all shadow prices were zero 1 .0 0 1.00 104.61 138.54 Table 14. S u b -b asin Shadow Prices of Irrigated Acres B asic M odel BI Increased I r r ig a tio n E ffic ie n cy S c e n ario s El E2 E3 (dollars). D ry Y e ar S c e n ario s Dl D2 A d d itio n al Ir r ig a te d A creage S c e n ario s Al A2 A3 Increased A g ric u ltu ra l P rice s S cen ario s Pl Pq i 1 0 3 .7 4 107 .4 2 1 8 8 .9 9 1 9 4 .0 6 8 6 .6 9 —0 — 9 0 .8 8 9 0 .8 8 8 8 .7 8 2 0 8 .7 3 2 8 4 .1 1 2 8 4 .8 2 1 0 0 .6 2 1 8 8 .9 1 1 9 4 .8 4 8 6 .7 2 —0 — 9 1 .5 5 9 1 .5 5 8 8 .7 8 1 8 0.21 2 4 8.69 3 9 5 .4 2 82.78 1 8 7 .0 7 1 9 1 .2 0 7 6 .5 7 2 0 .1 4 7 9 .4 4 7 9.44 7 8.02 1 8 6.38 2 5 1.69 4 1 7 0 .1 6 1 8 0 .1 3 1 8 6.67 1 9 1.20 1 6 5 .1 3 1 5 7.12 1 7 0.16 1 7 0 .1 6 1 6 6 .0 7 332 .9 7 4 4 9 .8 6 5 1 5 0 .4 8 1 5 7 .1 2 1 6 1.32 1 6 4 .6 1 1 4 6.84 1 4 2 .7 6 1 5 0.48 1 5 0.48 1 4 7 .7 7 2 8 9 .6 9 3 8 9 .6 4 6 1 5 0 .4 8 15 7 .1 2 1 6 1.32 1 6 4 .6 1 1 4 6.84 1 4 1 .3 1 1 5 0.48 1 5 0.48 14 7 .7 7 2 8 9 .6 9 3 8 9 .6 4 7 1 5 3.77 1 6 0 .3 8 1 6 4 .2 1 1 6 7 .2 5 1 5 0 .5 6 1 4 7.07 1 5 3.77 1 5 3.77 1 5 1 .4 4 2 9 2 .9 8 3 9 2 .9 3 8 8 9 .9 6 1 6 0.06 1 6 4 .2 1 1 6 7 .2 5 8 7 .1 7 8 4 .0 3 8 9 .9 6 8 9 .9 6 8 8 .7 9 1 7 7 .0 5 2 3 9 .5 5 9 1 4 4 .1 7 1 5 4 .4 7 1 6 0 .3 0 1 6 4 .0 3 1 3 9 .6 9 1 4 1 .5 3 1 4 4.17 1 4 4 .1 7 1 3 8 .9 0 2 8 3.38 3 8 3 .3 3 96 The shadow p r i c e s f o r i r r i g a t e d a c r e s i n t h e b a s i c mod el a r e p r e s e n t e d i n t h e f i r s t column o f T a b l e 14. T hes e v a l u e s i n d i c a t e w h a t an a d d i t i o n a l a c r e o f i r r i g a t e d l a n d would c o n t r i b u t e t o t h e v a lu e of th e o b j e c t i v e f u n c t i o n . The r e s u l t s o f t h e b a s i c m o d e l a r e t h e b e n c h m a r k by w h i c h t h e r e s u l t s o f t h e s c e n a r i o s w i l l be com pare d. the Thus, s c e n a r i o s become a s e r i e s o f njW h a t - I f " q u e s t i o n s , i.e ., g iv e n th e r e s u l t s of th e b a s i c m o d el, what i f a p a r t ic u l a r c om p on en t c h a n g e s ? R esu lts of Increased I r r ig a tio n E ffic ie n c y S cenarios One o f t h e p r i m a r y o b j e c t i v e s o f t h i s s t u d y w a s t o e v a l u a t e t h e e c o n o m i c and h y d r o l o g i c i m p l i c a t i o n s o f r i v e r m an a g em en t p o l i c i e s w h i c h a r e a i m e d a t i n c r e a s i n g i r r i g a ­ tio n efficien cies. H y d r o lo g ic Impacts As t h e l e v e l o f i r r i g a t i o n e f f i c i e n c y i n c r e a s e s , the q u a n t i t i e s o f d i v e r s i o n s and r e t u r n f l o w s d e c r e a s e and t h e d i s t r i b u t i o n of r i v e r flow throughout the year i s a lte r e d . I n t h e El s c e n a r i o , d i v e r s i o n i s r e d u c e d by 28 p e r c e n t and r e t u r n f l o w s f o r t h e May t o S e p t e m b e r i n t e r v a l a r e r e d u c e d by 36.4 p e r c e n t . I n t h e E2 s c e n a r i o , d i v e r s i o n s and r e t u r n f l o w s f o r t h e May t o S e p t e m b e r i n t e r v a l a r e r e d u c e d by 46 and 58.6 p e r c e n t r e s p e c t i v e l y fr o m t h e b a s i c m o d e l. E3 s c e n a r i o , In th e d i v e r s i o n s and r e t u r n f l o w s f o r t h e May t o S e p t e m b e r i n t e r v a l a r e r e d u c e d by 58.4 and 73.8 p e r c e n t 97 r e s p e c t i v e l y f r o m t h e b a s i c m o d el. B asin-w ide q u a n t i t i e s f o r d i v e r s i o n s and May t o S e p t e m b e r r e t u r n f l o w s f o r t h e b a s i c m odel and t h e s c e n a r i o s a r e l i s t e d i n Table. 8 and d i v e r s i o n s and r e t u r n f l o w s f o r t h e i n d i v i d u a l s u b - b a s i n s a r e l i s t e d i n T a b l e s 9 and 10 r e s p e c t i v e l y . B asin-w ide c r o p p i n g p a t t e r n s f o r t h e E l , E2 f and ES s c e n a r i o s a r e l i s t e d i n T a b l e 11. sub-basins are l i s t e d Cropping p a t t e r n s f o r th e i n d i v i d u a l i n A p p en d ix C. Economic I m p a c t s R e t u r n s t o a g r i c u l t u r e f o r t h e E l , E2, and ES s c e n a ­ r i o s a r e l i s t e d i n T a b l e 12. The c r o p p i n g p a t t e r n i s t h e sa m e i n s c e n a r i o s E2 a n d ES a n d t h e r e f o r e t h e r e t u r n s t o a g r i c u l t u r e does not change. The r e t u r n s t o a g r i c u l t u r e not include d iv e rsio n c o sts. T h u s, do th e value of th e o b jec ­ t i v e f u n c t i o n i s g r e a t e r f o r t h e ES s c e n a r i o t h a n f o r t h e E2 s c e n a r i o s i n c e l e s s w a t e r h a s b e e n d i v e r t e d . T otal r e t u r n s t o a g r i c u l t u r e f o r t h e e n t i r e b a s i n i n c r e a s e d 6.5 p e r c e n t o v e r t h e b a s i c m od el i n t h e El s c e n a r i o . T otal r e t u r n s t o a g r i c u l t u r e b a s i n - w i d e i n c r e a s e d 7=5 p e r c e n t o v e r t h e b a s i c m o d el i n t h e E2 and ES s c e n a r i o s . The shadow p r i c e f o r w a t e r i n s u b - b a s i n s I , 2, and 3 for t h e month o f A u g u s t i n c r e a s e d f r o m $59.50 t o $94.98 and t h e shadow p r i c e o f w a t e r i n s u b - b a s i n 8 f o r t h e m onth of A u g u s t d e c r e a s e d f r o m $57.37 t o 0 i n t h e El s c e n a r i o (shown i n T a b l e 1 3 ). Shadow p r i c e s f o r w a t e r i n a l l o t h e r m o n th s and s u b - b a s i n s w e r e 0 i n t h e E l s c e n a r i o . The E2 and ES 98 s c e n a r i o s had shadow p r i c e s o f w a t e r t h a t w e re 0 i n a l l m o n th s and s u o - b a s i n s and c o n s e q u e n t l y w e r e n o t i n c l u d e d i n T a b l e 13. The shadow p r i c e s o f i r r i g a t e d a c r e s a r e p r e ­ sented for e a c h s u b - b a s i n i n T a b l e 14. R e s u l t s o f t h e Dry Year S c e n a r i o s I n t n e Dl s c e n a r i o , w h i c h r e p r e s e n t s an a n n u a l f l o w a t S i d n e y o f 8.87 mmaf, d i v e r s i o n s i n c r e a s e d by 7.3 p e r c e n t o v e r t h e b a s i c m o d el and r e t u r n f l o w s i n c r e a s e d by 8.4 percent. I n t h e D2 s c e n a r i o , w h i c h r e p r e s e n t s an a v e r a g e a n n u a l f l o w a t S i d n e y o f 6.9 mmaf, d i v e r s i o n s d e c r e a s e d by 2.5 p e r c e n t and r e t u r n f l o w s d e c r e a s e d by 2.9 p e r c e n t fr o m t h e b a s i c m o d el l e v e l s . T o t a l d i v e r s i o n s and r e t u r n f l o w s a r e l i s t e d i n T a b l e 8 , w h i l e d i v e r s i o n s a n d r e t u r n f l o w s by s u b - b a s i n a r e l o c a t e d i n T a b l e s 9 and 10. B asin-w ide c r o p p i n g p a t t e r n s a r e p r e s e n t e d i n T a b l e 11 and c r o p p i n g p a t t e r n s for th e in d iv id u a l su b -b a sin s a re l i s t e d in A p p e n d ix C. I n t n e D2 s c e n a r i o , s u b - b a s i n s I and 2 h a d s l a c k or i d l e i r r i g a t e d a c r e a g e o f 5 ,5 9 0 and 83,244 a c r e s r e s p e c ­ tiv ely . the f i f t h A l s o t h e Y e l l o w t a i l and Tongue r e s e r v o i r s ended tim e i n t e r v a l , i.e., Septem ber, a t l e s s than f u l l c a p a c i t y i n t h i s s c e n a r i o . The tw o r e s e r v o i r s w e r e l e f t a t 11 and 89 p e r c e n t l e s s t h a n c a p a c i t y r e s p e c t i v e l y . tne i n a b i l i t y to f i l l W h ile t h e r e s e r v o i r s a t t h e end o f t h e i r r i g a t i o n s e a s o n may or may n o t be a d e s i r e d r e s e r v o i r m an ag em en t g o a l , t h e f a c t t h a t t h i s s c e n a r i o d e v i a t e s fro m 99 th e o t h e r s i s i n d i c a t i v e of th e s e v e r i t y of th e w a te r shortage in t h i s scenario. B a s i n - w i d e r e t u r n s t o a g r i c u l t u r e d e c r e a s e d by 6.85 p e r c e n t and 26.5 p e r c e n t f ro m t h e b a s i c model i n t h e Dl and D2 s c e n a r i o s r e s p e c t i v e l y . l i s t e d i n T a b l e 12. acres are lis te d R eturns to a g r i c u lt u r e are Shadow p r i c e s o f w a t e r and i r r i g a t e d i n T a b l e s 13 and 14 r e s p e c t i v e l y . R e su lts of Increased Ir r ig a te d Acreage S c e n a r io s T a k in g i n t o a c c o u n t t h e i n c r e a s e d a c r e a g e i n t h e A l , A2, and A3 s c e n a r i o s , d i v e r s i o n s on a p e r a c r e b a s i s w e r e 7.11, 7 .0 1 , and 6.90 a c r e - f e e t p e r a c r e a c r e - f e e t per a c r e in t h e b a s i c model. co m p a red t o 7.24 T his o ccu rs because th e c ro p p in g p a t t e r n which accom panied th e a d d i t i o n a l a c r e s included l e s s w ater in te n s iv e crops. However, t h e a d d i ­ t i o n a l a c r e a g e r e s u l t e d in i n c r e a s e s in t o t a l d i v e r s i o n s of 12 p e r c e n t , 23.7 p e r c e n t , and 39.8 p e r c e n t r e s p e c t i v e l y f o r t h e A l, A2, and A3 s c e n a r i o s o v e r t h e l e v e l of t h e b a s i c m odel ( s e e T a b l e 8). R eturns to a g r i c u lt u r e percent, i n c r e a s e d by 10.6 p e r c e n t , 20.9 and 34.8 p e r c e n t f o r t h e A l , A2, and A3 s c e n a r i o s resp ectiv ely . R etu rn s to a g r i c u l t u r e for each su b -b asin a r e l i s t e d i n T a b l e 12 b u t s h o u l d n o t b e v i e w e d a s p r o j e c ­ t i o n s of p o t e n t i a l i r r i g a t e d a g r i c u l t u r a l developm ent in th e i n d i v i d u a l s u b - b a s i n s a s t h e a d d i t i o n a l a c r e s were d i s t r i b u t e d a c c o rd in g t o t h e d i s t r i b u t i o n of c u r r e n t l y 100 i r r i g a t e d a c r e s and n o t a c c o r d i n g t o any p r o j e c t i o n s o f w h e r e d e v e l o p m e n t c o u l d be e x p e c t e d t o o c c u r . Shadow p r i c e s f o r w a t e r , by t i m e i n t e r v a l and s u b - b a s i n , and i r r i g a t e d a c r e s by s u b - b a s i n a r e l i s t e d i n T a b l e s 13 and 14 resp ectiv ely . R e su lts of the Increased A g r ic u ltu r a l P r ic es Scenarios S in ce t h e r e l a t i v e v a lu e of th e c ro p s w ere n o t changed as a r e s u l t of i n c r e a s i n g th e l e v e l of r e t u r n s over v a r i ­ a b le c o s t , t h e c ro p p in g p a t t e r n d id n o t change from t h a t of t h e b a s i c model a n d . c o n s e q u e n t l y n e i t h e r d i d d i v e r s i o n s or re tu rn flow s. The i n c r e a s e d l e v e l o f p r i c e s r e c e i v e d r e s u l t e d i n i m p a c t s on o t h e r e c o n o m i c v a r i a b l e s . The c h a n g e s i n r e t u r n s t o a g r i c u l t u r e a r e l i s t e d i n T a b l e 12. T a b l e s 13 a n d 14 c o n t a i n t h e s h a d o w p r i c e s o f w a t e r , by t i m e i n t e r v a l and s u b - b a s i n , and i r r i g a t e d a c r e a g e , by s u b ­ basin. C a v e a t s and L i m i t a t i o n s o f T h i s S tud y Any m o d e l, by d e f i n i t i o n , m u s t make c e r t a i n s i m p l i ­ f y i n g a ssu m p tio n s as a p art of th e m odeling p r o c e s s . Th ese a s s u m p t i o n s i n v a r i a b l y i n t r o d u c e some p o t e n t i a l f o r e r r o r i n p a r a m e t e r v a l u e s u s e d i n t h e m o d e l. I t i s im perative t h a t t h e r e s u l t s o f an y m o d e l b e e v a l u a t e d i n l i g h t o f t h e a s s u m p t i o n s t h a t w e r e i n c o r p o r a t e d i n t h e c o n s t r u c t i o n of. t h e m o d e l. 101 One o f s e v e r a l i m p o r t a n t a s s u m p t i o n s o f t h i s model i s t h a t i t i s l i m i t e d t o one i r r i g a t i o n scheme f o r e a c h c r o p . In o t h e r w o rd s, t h e c r o p i s grown o n ly i f t h e r e i s enough w a t e r t o m e e t one s e t o f n e t i r r i g a t i o n r e q u i r e m e n t s w h i c h a re s p e c i f i e d fo r each tim e i n t e r v a l . This te n d s to over­ e s t i m a t e th e economic im p a c ts a s s o c i a t e d w i t h w a te r s c a r c i t y b e c a u s e i t d o e s n o t a l l o w t h e c r o p t o be grown under a d im in is h e d w a te r regim e w ith a c o rre sp o n d in g reduc­ tio n in y ie ld . T h u s, i f w a t e r i s s c a r c e and t h e r e i s n o t eno u g h w a t e r t o grow a l f a l f a h a y , f o r e x a m p le , a t t h e s t a t e d i r r i g a t i o n r e q u i r e m e n t s t h e m odel m u s t r e v e r t t o so m e o t h e r c r o p w h i c h u s e s l e s s w a t e r a n d m o s t l i k e l y h a s a s u b s t a n t i a l l y low er o b j e c t i v e f u n c t i o n v a lu e . A c c o m o d a ti o n o f m u l t i p l e i r r i g a t i o n sc h e m e s i n t h e model i s s t r a i g h t ­ forw ard but th e req u ire d data i s p re s e n tly u n av ailab le. I t i s i m p o r t a n t t o rem ember t h a t t h i s model u s e s re tu rn s to a g ric u ltu re in th e o b je c tiv e fu n c tio n , r e tu r n s over v a r ia b le c o s ts . Thus, i.e., the r e s u l t s presen ted h e r e r e p r e s e n t a s h o r t run s o l u t i o n r a t h e r th a n a long run so lu tio n . More i m p o r t a n t l y , t h e u s e o f ROVCs o v e r e s t i ­ m a te s t h e economic v a l u e s in t h e r e s u l t s p r e s e n t e d in t h i s chapter. T h u s, t h e shadow p r i c e s a s s o c i a t e d w i t h w a t e r and i r r i g a t e d a c r e s a r e o v e r s t a t e d due t o t h e u se o f ROVCs be ca u se f i x e d c o s t s have not been c o n s id e re d . I t s h o u l d be r e m e m b e r e d a l s o t h a t t h e b a s i c model was c a l i b r a t e d t o a r e c e n t h i s t o r i c p e r i o d of t i m e when t h e 102 av erag e flo w s of th e Y ello w sto n e R iv er were h ig h e r th an th e long run average. T h u s7 t h e m odel would t e n d t o u n d e r s t a t e t h e p h y s i c a l s c a r c i t i e s o f w a t e r t h a t w o u ld be p r e s e n t a t a low er l e v e l of flow . , How ever7 t h e Dl s c e n a r i o r e p r e s e n t s a I f l o w much c l o s e r t o t h e t h e l o n g r u n a v e r a g e f l o w a n d t h e r e f o r e c o r r e c t s t h i s s i t u a t i o n som ewhat. S u g g e s t e d R e f i n e m e n t s o f T h i s Model As w i t h any m o d e l , an a l m o s t i n f i n i t e number o f r e f i n e m e n t s c o u l d b e i n c o r p o r a t e d and w o u ld be d e s i r a b l e i n some s e n s e . H o w ev er7 some r e f i n e m e n t s f o r t h i s p a r t i c u l a r mod el c o u l d e a s i l y be made and w o u ld g r e a t l y i n c r e a s e t h e flex ib ility o f t h i s m o d el. The use o f n e t r e t u r n s r a t h e r t h a n r e t u r n s o v e r v a r i a b l e c o s t s as o b j e c ti v e f u n c tio n v a lu e s fo r th e a g r i ­ c u l t u r a l c r o p s w o u l d r e s u l t i n l o n g r u n s o l u t i o n s and w o u ld s i m p l i f y i n t e r p r e t a t i o n o f t h e shadow p r i c e s a s s o c i a t e d w ith the v a rio u s reso u rces. The e x p a n s i o n o f t h i s model f r o m f i v e m o n t h l y i n t e r v a l s t o one w h i c h w o u l d i n c l u d e t h e e n t i r e y e a r w o u ld s i g n i f i c a n t l y i n c r e a s e t h e v a lu e of t h e m odel. I t w o u ld f a c i l i t a t e use of t h e model i n s c e n a r i o s o f f u t u r e d e v e l o p m e n t and t h e i m p a c t o f r i v e r m an ag em en t p o l i c i e s on f a c t o r s o t h e r t h a n i r r i g a t e d a g r i ­ c u ltu re, s u c h a s f i s h and w i l d l i f e h a b i t a t , m u n i c i p a l u s e , and e n e r g y and o t h e r i n d u s t r i a l u s e s o f w a t e r w h i c h a r e n o t l i m i t e d t o t h e summer m o n th s . 103 I t w o u l d be u s e f u l t o i n c o r p o r a t e o t h e r f a c t o r s a s s o c i a t e d w i t h i r r i g a t e d a g r i c u l t u r a l p r o d u c t i o n more rea listic ally i n t o t h e m o d el. T h i s w o u l d i n c l u d e su ch p r o d u c tio n f a c t o r s as m u l t i p l e i r r i g a t i o n schemes, d if­ f e r e n t d i s t r i b u t i o n and a p p l i c a t i o n s y s t e m s f o r i r r i g a t i o n , d i f f e r e n t f a r m i n g s y s t e m s , d i f f e r e n t l e v e l s o f m anagem ent and p h y s i c a l f a c t o r s s u c h a s t h e v a r i e t y o f s o i l t y p e s found i n t h e b a s in . I f 104 Chapter 6 C o n c l u s i o n s , P o l i c y I m p l i c a t i o n s and S u g g estio n s f o r F u rth e r Research T h is stu d y has been d ev o te d t o m odeling t h e Yellow­ s t o n e R i v e r B a s i n i n Montana so t h a t t h e e c o n o m ic and h y d r o l o g i c i m p l i c a t i o n s o f a l t e r n a t i v e w a t e r man agem ent p o l i c i e s c o u l d be e s t i m a t e d . The i n i t i a l e m p h a s i s of t h i s s t u d y was t o e v a l u a t e t h e i m p l i c a t i o n s o f i n c r e a s i n g t h e t e c h n i c a l e f f i c i e n c y of w a ter used f o r i r r i g a t i o n . study p ro g re sse d , As t h e o p p o rtu n itie s to ev alu ate other a lte r n a ­ t i v e s c e n a r i o s w e r e r e c o g n i z e d and e x p l o i t e d . The v a s t c o m p l e x i t i e s o f t h e h y d r o l o g i c and e c o n o m ic s y s t e m s i n t h e b a s i n a s w e l l . a s t h e maze o f l e g a l and o t h e r i n s t i t u t i o n a l f a c t o r s w h i c h i n f l u e n c e w a t e r u s e a l l co m b in e t o s u g g e s t t h a t a c o m p r e h e n s i v e u n d e r s t a n d i n g o f w a t e r m an agem en t i m p l i c a t i o n s would be, a t t h e v e r y l e a s t , t a x i n g . Not a l l o f t h e i s s u e s a r e r e s o l v e d by t h i s s t u d y , b u t a f r a m e w o r k was d e v e l o p e d w h e r e b y many o f t h e s e i s s u e s can be i n v e s t i g a t e d i n f u t u r e work. C o n c l u s i o n s and P o l i c y I m p l i c a t i o n s The r e s u l t s o f t h e b a s i c model i n d i c a t e t h a t w h i l e t h e r e i s an a b u n d an ce of w a te r i n m o st p l a c e s m o st of th e tim e, s i t e and t i m e s p e c i f i c s h o r t a g e s o f w a t e r do o c c u r i n 105 t h e Y e l l o w s t o n e B a s i n a s i n d i c a t e d by t h e n o n z e r o shadow p r i c e s o f water in four of the n in e s u b -b a sin s . le v e l of ir r ig a t io n e f f ic ie n c y As t h e in c r e a s e s in the i r r i g a t i o n e f f i c i e n c y s c e n a r i o s , r e t u r n s t o a g r i c u l t u r e i n c r e a s e over ' â– â– t h e l e v e l o f t h e b a s i c m o d e l i n E l a n d E2, w h i l e h o l d i n g c o n s t a n t f r o m E2 t o E3. This i n d i c a t e s t h a t t h e r e a re g a i n s t o be made by i n c r e a s i n g t h e l e v e l of i r r i g a t i o n efficien cy , a t l e a s t m a r g i n a l l y , above c u r r e n t l e v e l s . How ever, a c l o s e r e x a m i n a t i o n o f t h e i n d i v i d u a l s u b ­ b a sin s in d ic a t e s t h a t m arginal in c re a s e s in i r r i g a t i o n e f f i c i e n c y do r e s u l t i n d e t r i m e n t a l e c o n o m ic i m p a c t s t o certain irrig ato rs. At t h e l e v e l o f i r r i g a t i o n e f f i c i e n c y i m p l i e d by t h e E l s c e n a r i o , i f w a t e r i s u s e d o p t i m a l l y a s d e t e r m i n e d i n t h e m o d e l , w a t e r b e co m es more s c a r c e i n s u b ­ basins I , 2 , and 3 t h a n i s t r u e f o r t h e b a s i c m o d el. T h i s i s i n d i c a t e d by t h e i n c r e a s e d shadow p r i c e o f w a t e r i n those su b -b a sin s. A co m p arisio n of th e r e t u r n s t o a g r i c u l ­ t u r e i n t h o s e s u b - b a s i n s b e t w e e n t h e b a s i c m o d el and t h e El s c e n a r i o shows a s i g n i f i c a n t r e d i s t r i b u t i o n o f in co m e a s a r e s u l t of th e in c r e a s e d i r r i g a t i o n e f f i c i e n c y . R eturns to a g r i c u l t u r e in s u b - b a s in 3 a re reduced w h ile th o se in sub­ basin 2 are increased. The i n c r e a s e s i n s u b - b a s i n 2 a r e more t h a n enou gh t o o f f s e t t h e d e c r e a s e s i n s u b - b a s i n 3, so t h e r e s u l t i s an i n c r e a s e i n r e t u r n s t o t h e e n t i r e b a s i n . In s u b - b a s i n 8 h o w e v e r , t h e shadow p r i c e o f w a t e r f a l l s t o z e r o i n t h e El s c e n a r i o i n d i c a t i n g t h a t w a t e r s c a r c i t y has 106 b e e n e l i m i n a t e d by t h e i n c r e a s e i n i r r i g a t i o n e f f i c i e n c y and a h i g h e r l e v e l o f r e t u r n s t o a g r i c u l t u r e i s a c h i e v e d a s a resu lt. A c h i e v i n g t h e l e v e l o f i r r i g a t i o n e f f i c e n c y i m p l i e d by t h e E2 s c e n a r i o i n d i c a t e s t h a t a l l w a t e r s c a r c i t i e s h a v e b e e n e l i m i n a t e d when t h e 196 3 -1 9 7 7 a v e r a g e f l o w o c c u r s . T h u s , i n some s u b - b a s i n s , a s t h e l e v e l o f i r r i g a t i o n e f f i c ­ i e n c y i s i n c r e a s e d t h e r e s u l t w i l l be f i r s t an i n c r e a s i n g and t h e n a d e c r e a s i n g l e v e l o f shadow p r i c e s o f w a t e r . The e x p l a n a t i o n t o t h i s phenomenon i s f a i r l y s t r a i g h t ­ f o r w a r d though n o t i n i t i a l l y o b v io u s . In th o se su b -b a sin s w h e r e t h e b a s i c m o d el g e n e r a t e s n o n z e r o shadow p r i c e s , w a t e r i s a b i n d i n g c o n s t r a i n t on t h e l e v e l o f a g r i c u l t u r a l production. In itial i n c r e a s e s in t h e l e v e l of i r r i g a t i o n e f f i c ie n c y , w ith e v ery th in g e ls e c o n s ta n t, w i l l r e s u l t e f f e c t i v e l y i n more w a t e r b e i n g made a v a i l a b l e due t o decreased d iv e rs io n requirem ents. However, i n t h o s e s u b ­ b a s i n s which a re i n i t i a l l y s h o r t of w a te r , t h e in c r e a s e d w a t e r a v a i l a b i l i t y w i l l r e s u l t i n a move t o w a r d s a more, o p tim al cropping p a tt e r n . Thus, e i t h e r t h e i n c r e a s e d n e t i r r i g a t i o n r e q u i r e m e n t s a s s o c i a t e d w i t h t h e new c r o p p i n g p a t t e r n , which o c c u rs because t h e h i g h e s t v a lu e d c ro p s ten d t o be t h e m o s t w a t e r i n t e n s i v e , o r t h e i n c r e a s e d e co n o m ic v a l u e a s s o c i a t e d w i t h t h e new c r o p p i n g p a t t e r n o r a c o m b i­ n a tio n of b oth r e s u l t s in th e in c r e a s e d v alu e of w a te r as reflected i n h i g h e r shadow p r i c e s . 107 In c re a s e s in r e tu r n s to a g r i c u lt u r e w i l l continue u n t i l enough w a t e r b e co m es a v a i l a b l e t o a l l o w t h e c o n s t r a i n e d g l o b a l l y o p tim um c r o p p i n g p a t t e r n i m p l i e d i n t h e m odel t o be a c h i e v e d . The c o n s t r a i n e d g l o b a l l y optimum c r o p p i n g p a t t e r n i s t h a t w h i c h i s a c h i e v e d when w a t e r i s n o t a b i n d i n g c o n s t r a i n t i n an y s u b - b a s i n and t i m e i n t e r ­ val. The g l o b a l l y o p tim u m c r o p p i n g h a s b e e n a c h i e v e d a t th e p o i n t where i r r i g a t i o n e f f i c i e n c y i s in c r e a s e d t o th e l e v e l o f t h e E2 s c e n a r i o . The c r o p p i n g p a t t e r n s f o r t h e i n d i v i d u a l s u b - b a s i n s w h i c h c o l l e c t i v e l y make up t h e c o n s t r a i n e d g l o b a l l y o p tim u m c r o p p i n g p a t t e r n w e r e a c h i e v e d i n some s u b - b a s i n s a t . t h e l e v e l o f i r r i g a t i o n e f f i c i e n c y i n th e b a s i c model, in s u b - b a s i n 8 a t th e l e v e l of i r r i g a t i o n e f f i c i e n c y in th e El sc e n a rio , and i n t h e r e s t o f t h e s u b ­ b a s i n s a t t h e l e v e l o f i r r i g a t i o n e f f i c i e n c y i n t h e E2 scenario. I n c r e a s e d i r r i g a t i o n e f f i c i e n c y beyond t h e l e v e l o f E2 w ill not increase re tu rn s to a g ric u ltu re but w ill increase th e v a lu e of o b j e c t i v e f u n c t i o n v a lu e as d i v e r s i o n c o s t s continue to d ecrease. This s u g g e s ts t h a t p o l i c i e s designed t o i n c r e a s e t h e l e v e l o f i r r i g a t i o n e f f i c i e n c y m u st be b a s e d o n , f i r s t , d e t e r m i n i n g t h e l e v e l of e f f i c i e n c y w h i c h i s d e s i r e d a s a g o a l and d e t e r m i n i n g t h e p o t e n t i a l e c o n o m ic im p a cts w i t h i n each s u b - b a s in of a c h ie v in g t h a t g o a l. a n a l y s i s s h o u l d be c o m p l e t e d p r i o r t o i m p l e m e n t a t i o n of these p o licies. Such 108 D e t e r m in a t io n of th e o p tim a l l e v e l of i r r i g a t i o n efficien cy i s i m p l i e d by t h e b e n e f i t / c o s t a n a l y s i s p r e s e n t e d i n C h a p t e r 2. The r e s u l t s o f t h i s w ork a r e i n d i c a t i v e of th e im p a c ts of in c r e a s e s in i r r i g a t i o n e f f i c ­ i e n c y b u t do n o t s u g g e s t w h a t l e v e l o f e f f i c i e n c y i s d esirab le. W h il e t h i s s t u d y made no a t t e m p t t o d e t e r m i n e t h e c o s t o f a c h i e v i n g and m a i n t a i n i n g a l t e r n a t i v e l e v e l s of i r r i g a t i o n e f f i c i e n c y , an e x a m i n a t i o n o f t h e r e t u r n s t o a g r i c u lt u r e a s s o c ia te d w ith the in cre ased i r r i g a t i o n e f f i c ­ ien cy s c e n a r i o s does s u g g e s t th e l i m i t s t o e c o n o m ic a lly f e a s i b l e im provem ents. The i n c r e a s e i n e f f i c i e n c y fro m t h e b a s i c m o d el t o t h e E l s c e n a r i o r e s u l t s i n i n c r e a s e d r e t u r n s t o a g r i c u l t u r e o f a b o u t $7.2 m i l l i o n or $12.66 p e r a c r e . T h u s, t h e c o s t o f a c h i e v i n g t h e e f f i c i e n c y i n c r e a s e fr o m 19 t o 28 p e r c e n t i s e c o n o m i c a l l y f e a s i b l e o n l y i f i t c a n b e a c c o m p l i s h e d a t a c o s t o f l e s s t h a n $12.66 p e r a c r e . This f i g u r e i s on an a n n u a l b a s i s and i s s t a t e d i n t h e a b s e n c e o f p r e s e n t v a l u e c a l c u l a t i o n s w h i c h w o u ld r e d u c e t h e v a l u e o f a n n u a l c o n t r i b u t i o n s i n f u t u r e y e a r s of t h e p l a n n i n g horizon. S u b t r a c t i n g f i x e d c o s t s from th e o b j e c t i v e fu n c ­ t i o n v a l u e s w o u ld a l s o r e d u c e . t h e v a l u e s s t a t e d h e r e . The d im inishing re tu rn s a sso c ia te d w ith increased i r r i g a t i o n e f f i c i e n c y i s i l l u s t r a t e d by t h e f a c t t h a t e f f i c i e n c y i n c r e a s e s f r o m t h e El t o E2 l e v e l s , i.e., 28 t o 37 p e r c e n t , i s a c c o m p a n i e d by i n c r e a s e d r e t u r n s t o a g r i c u l t u r e of o n l y 109 $2.05 p e r a c r e . increase The i n c r e a s e f r o m E2 t o ES d o e s n o t the r e tu r n s to a g ric u ltu r e . T h e r e i s no a p r i o r i r e a s o n t o b e l i e v e t h a t t h e o p t i m a l l e v e l o f i r r i g a t i o n e f f i c i e n c y w i l l n e c e s s a r i l y be h ig h e r th a n th e l e v e l which overcom es th e r e d i s t r i b u t i v e im pacts p re se n te d in th ese r e s u l t s in a p a r t i c u l a r subbasin. The r e d i s t r i b u t i v e i m p a c t s may be o n l y t r a n s i t o r y i f t h e o p t i m a l i r r i g a t i o n e f f i c i e n c y l e v e l i s h i g h enough b u t w i l l be p e r m a n e n t i f i t i s not. The s p e c i f i c l e v e l o f t h e i m p a c t s w i l l be u n i q u e t o e a c h i n d i v i d u a l s u b - b a s i n . Thus i t i s n o t c l e a r t h a t g e n e r a l or n o n s p e c i f i c p o l i c i e s o f i n c r e a s e d i r r i g a t i o n e f f i c i e n c y can be a c c o m p l i s h e d w i t h o u t s i g n i f i c a n t d e t r i m e n t a l e c o n o m ic i m p a c t s t o c e r t a i n w ater u se rs. T h ese i m p a c t s may be e i t h e r t e m p o r a r y or p e r m a n e n t d e p e n d i n g on p a r t i c u l a r c i r c u m s t a n c e s . There a p p e a r s t o be a t e n d e n c y among w a t e r p l a n n i n g o f f i c i a l s t o b e l i e v e t h a t w h a t e v e r l e v e l o f i r r i g a t i o n e f f i c i e n c y can be a c h i e v e d above c u r r e n t l e v e l s w i l l be b e n e f i c i a l t o a l l w ater u se rs. th is T h is b e l i e f i s c o n t r a r y t o th e r e s u l t s of study. The d r y y e a r s c e n a r i o s i n d i c a t e d , a s m i g h t be e x p e c ­ t e d , t h a t w a t e r s c a r c i t i e s a r e i n c r e a s e d i n lo w f l o w y e a r s . The Dl s c e n a r i o i s b a s e d on a n n u a l r i v e r f l o w s a t S i d n e y o f 8.87 mmaf w h i c h i s o n l y s l i g h t l y b e lo w t h e 1 9 3 4 -1 9 8 0 a v e r ­ age o f 8.9 mmaf. Thus, t h e Dl s c e n a r i o i s more n e a r l y t h e long run av erag e l e v e l of r i v e r flow than t h a t used in th e HO b a s i c m o d e l , w h i c h was b a s e d on t h e a v e r a g e f l o w f o r t h e y e a r s 1 9 6 3 -1 9 7 7 o f 10.2 mmaf. p articu lar, illu s tra te The d r y y e a r s c e n a r i o s , in th e i m p l i c a t i o n s of h av in g or not having sto ra g e f a c i l i t i e s on t h e r i v e r . The w i d e f l u c t u a t i o n s i n r e t u r n s t o a g r i c u l t u r e i n t h e t h r e e u p p e r s u b - b a s i n s a r e i n d i c a t i v e o f t h e v a l u e of s t o r a g e and a l s o o f th e d e c r e a s e s i n r i s k t o w a t e r u s e r s a s s o c i a t e d w ith th e a v a i l a b i l i t y of s to ra g e f a c i l i t i e s . D e p e n d in g on t h e i n s t i t u t i o n a l r e g i m e , th e upstream , u s e r s may h a v e f i r s t u s e o f t h e w a t e r i n w h i c h c a s e w a t e r w o u l d n o t be g o i n g t o t h e h i g h e s t v a l u e d u s e . In t h a t s i t u a t i o n t h e v a l u e o f s t o r a g e w o u ld be g r e a t e r t h a n t h a t i m p l i e d by th e r e s u l t s of t h i s stu d y . A com prehensive b e n e f i t / c o s t a n a l y s i s w o u ld be n e c e s s a r y t o a c c u r a t e l y d e t e r m i n e t h e n e t s o c i a l v a lu e of s t o r a g e in th e b a s in . An e x a m i n a t i o n of t h e shadow p r i c e s o f i r r i g a t e d a c r e a g e f o r t h e d r y y e a r s c e n a r i o s i n d i c a t e s t h a t th e v a lu e of i r r i g a t e d lan d i s v e r y d e p e n d a n t on a r e l i a b l e w a t e r s o u r c e t h r o u g h o u t t h e irrig atio n season. I n t h e D2 and a l s o i n t h e A3 s c e n a r i o s , shadow p r i c e s o f w a t e r o f $1.00 a p p e a r i n v a r i o u s t i m e i n t e r v a l s and s u b ­ basins. T hes e r e s u l t fr o m t h e f a c t t h a t t h e r e s e r v o i r s a r e n o t f i l l e d a t t h e e nd o f t h e i r r i g a t i o n s e a s o n i n t h e s e scenarios. The tw o r e s e r v o i r s , t h e Y e l l o w t a i l dam i n s u b ­ b a s i n 4 and t h e Tongue dam i n s u b - b a s i n 6, have! an a c t i v i t y w h i c h p l a c e s a v a l u e on t h e c a r r y - o v e r o f w a t e r beyon d t h e Ill irrig a tio n season. T h i s a c t i v i t y was g i v e n a $1.00 p e r a c r e - f o o t o b j e c t i v e f u n c t i o n v a l u e a s an i n c e n t i v e t o t h e m o d el so t h a t i t w o u ld n o t d r a i n t h e r e s e r v o i r s a t t h e end of th e i r r i g a t i o n season. Thu s, i n t h e D2 and A3 s c e n a r i o s , w h e r e w a t e r i s v e r y s c a r c e , t h e $1.00 b ecom es t h e o p p o r t u n i t y c o s t o f n o t h a v i n g an a d d i t i o n a l a c r e - f o o t of w ater to lea v e in th e r e s e r v o i r s . I n t e r p r e t a t i o n of the r e s u l t s of the dry year s c e n a r i o s m u s t be made i n l i g h t of t h e t a c i t a s s u m p t i o n of a p r i o r i knowledge of d i m i n i s h e d r i v e r f lo w s . The f a c t t h a t t h e D2 s c e n a r i o r e s u l t s i n i r r i g a t e d a c r e s b e i n g t a k e n o u t o f p r o d u c t i o n i n s u b - b a s i n s I and 2 s u g g e s t s t h e s e r i o u s n e s s o f t h e p o t e n t i a l c o n f l i c t w h i c h may a r i s e i n t h e Y e l l o w s t o n e B a s i n d u r i n g lo w f l o w y e a r s . t h a t w a te r becomes v e r y s c a r c e , In the event t h e a g r i c u l t u r a l demand f o r w a t e r w i l l be i n c o n f l i c t w i t h t h e c u r r e n t minimum i n s t r e a m r e s e r v a tio n s fo r the a v a ila b le w ater su p p lie s. In r e a l i t y , u n l e s s t h e d i m i n i s h e d w a t e r s u p p l i e s w e r e known i n a d v an c e w ith c e r t a i n t y , i r r i g a t e d a c r e s would n o t a c t u a l l y sta n d i d l e b u t w o u ld be u t i l i z e d i n d i m i n i s h e d i r r i g a t e d p r o d u c ­ tio n . However, t h e f a c t t h a t t h e model c a l l s f o r d e c r e a s e s i n c r o p p e d a c r e a g e by o v e r 8 0 ,0 0 0 a c r e s i s i n d i c a t i v e of t h e p o t e n t i a l c o n f l i c t i n v o l v e d and t h e p o t e n t i a l e c o n o m ic im pacts. The r e s u l t s o f t h e i n c r e a s e d p r i c e s and a d d i t i o n a l ir r ig a t e d acreage sc e n a r io s as v a r ia t io n s of the b a sic 11 2 I model d i d n o t p r e s e n t any u n e x p e c t e d r e s u l t s . However? t h e i n c r e a s e d a g r i c u l t u r a l p r i c e s s c e n a r i o s d i d i l l u s t r a t e an obvious but o f t e n o v erlooked f a c t t h a t the va lu e of w ater t o i r r i g a t e d a g r i c u l t u r e i s n o t s t a t i c b u t i s d e p e n d e n t on th e v a lu e of th e a g r i c u l t u r a l p r o d u c ts produced. The i n c r e a s e d a g r i c u l t u r a l p r i c e s and i r r i g a t e d a c r e a g e s c e n a r i o s a r e more s i g n i f i c a n t when c o n s i d e r e d i n j o i n t occurrence w ith the oth er sc e n a rio s thereby exag g eratin g the i m p l i c a t i o n s o f v a r i o u s w a t e r m an ag em en t p o l i c i e s . S u g g estio n s fo r F u rth e r Research The r e s u l t s o f t h e b a s i c m o d e l a n d t h e s c e n a r i o s a r e a l l p r e s e n t e d i n t h e c o n t e x t o f a c e t e r i s p a r i b u s a ssu m p ­ tio n , i.e.? each of th e s c e n a r i o s i s in th e fram ework of w h a t i f on e v a r i a b l e c h a n g e s and e v e r y t h i n g e l s e r e m a i n s constant? The m o s t o b v i o u s e x t e n s i o n s o f t h e work p r e ­ s e n t e d i n t h i s s t u d y w o u ld be t o r e l a x t h e c^J l^ x J-S gai,lfcm.S a s s u m p t i o n and i n v e s t i g a t e t h e i m p a c t s o f c o m b i n a t i o n s o f f a c t o r s a f f e c t i n g r i v e r m anagem ent p o l i c i e s . Such work w o u ld r e s u l t i n t h e d e t e r m i n a t i o n o f p o t e n t i a l e c o n o m ic im p a c ts of i n c r e a s e d i r r i g a t i o n e f f i c i e n c y over a wider range of v a r i a b l e s . Sim ultaneously? i n v e s t i g a t i o n b a s e d on t h e s t o c h a s t i c n a t u r e o f t h e o c c u r r e n c e and m a g n i t u d e of p h y s i c a l and e c o n o m i c v a r i a b l e s b o t h i n d e p e n d e n t l y and j o i n t l y would p ro v id e u s e f u l i n f o r m a t i o n t o p o l i c y makers. I n a d d i t i o n , more d e t a i l e d a n a l y s i s o f t h e s i t e s p e c i f i c f a c t o r s on t h e p o t e n t i a l e c o n o m ic i m p a c t s w o u ld 113 p r o v i d e i n f o r m a t i o n a b o u t t h e k i n d and e x t e n t o f w a t e r m an a g em en t w h i c h can be a p p l i e d i n e a c h o f t h e s u b - b a s i n s . T h i s , i n t u r n , may h a v e i m p l i c a t i o n s , f o r e x a m p l e , on t h e s o c i a l l y d e s i r a b l e n a t u r e and e x t e n t o f f e d e r a l and s t a t e su p p o rt f o r i r r i g a t i o n p r o j e c t developm ent. In a d d itio n , b e n e f i t/ c o s t s tu d ie s r e la te d to in c re a se s in i r r i g a t i o n e f f i c i e n c y a s w e l l a s s t o r a g e f a c i l i t i e s and o t h e r w a t e r m an a g em en t a l t e r n a t i v e s a r e i n d i c a t e d by t h e r e s u l t s of th is study. F u r t h e r work i n m o d e l i n g t h e h y d r o l o g y o f t h e b a s i n w o u l d be d e s i r a b l e . E m p i r i c a l d e t e r m i n a t i o n of r e t u r n flow p a t t e r n s h a s p r o v e n t o be a v e r y d i f f i c u l t t a s k and a d d i ­ t i o n a l work t o d e f i n e r e t u r n f l o w p a t t e r n s a s w e l l a s s e n s i t i v i t y a n a l y s i s of th e r e s u l t s p re s e n te d h e re w ith r e g a r d t o a l t e r n a t i v e r e t u r n flo w p a t t e r n s would c o n t r i b u t e much t o t h e p o s s i b i l i t y o f w e l l i n f o r m e d w a t e r m anagem ent p o licies. In a d d i t i o n , i s s u e s r e g a r d i n g w a te r q u a l i t y must be a d d r e s s e d on a s i t e s p e c i f i c b a s i s a s a p a r t o f an o v e r a l l w a t e r m an ag em en t p l a n . The r e s u l t s p r e s e n t e d i n t h i s w o r k a r e d o n e i n t h e a b s e n c e o f t h e l e g a l and i n s t i t u t i o n a l f r a m e w o r k i n t h e basin. For e x a m p l e , t h e income r e d i s t r i b u t i o n w h i c h o c c u r s a s i r r i g a t i o n e f f i c i e n c y i n c r e a s e s may be e x a g g e r a t e d or d i m i n i s h e d by t h e w a t e r r i g h t s r e g i m e and o t h e r i n s t i t u ­ tio n a l f a c to r s w ith in the basin. F u r t h e r work i s n e c e s s a r y . 114 t o e v a l u a t e t h e i m p a c t o f t h e i n s t i t u t i o n a l and l e g a l m e c h a n i s m s on t h e r e s u l t s r e p o r t e d h e r e . 115 APPENDICES 116 APPENDIX A BUDGETS I 117 Table 15o I r r i g a t e d A l f a l f a f o r S u b - b a s i n s I f 2 , 3 , and 4 . RETURNS (I) $ 3 0 0 .0 0 F e r t i l i z e r and A p p l i c a t i o n (2) $ 1 1 .9 0 Crop C h e m i c a l s (3) 3.60 I r r i g a t i o n Labor (4) 6.00 M achinery: F u e l , O i l , R e p a irs (5) 31.03 Pickup V a r ia b le C osts (6) 5.00 M i s c e l l a n e o u s E x p en s e (7) 7.17 Other (8) 6.60 (9) 1.37 (10) 18.60 TOTAL VARIABLE COSTS (11) $ 9 1 .2 7 RETURN OVER VARIABLE COST (12) $ 2 0 8 .7 3 Y ield (5 Tons x $ 6 0 .0 0 ) VARIABLE COSTS (tw ine) I n t e r e s t on O p e r a t i n g C a p i t a l M a c h i n e r y Labor ( 4 . 6 5 h r . x $ 4 .0 0 ) B a s e d on d a t a f r o m F o g l e and L u f t (1980). 118 T able 16. I r r i g a t e d A l f a l f a f o r Sub- â– basins 5 and 7. RETURNS Cl) $ 2 4 0 .0 0 Stand E s ta b lis h m e n t (2) $ F e r t i l i z e r and A p p l i c a t i o n (3) 28.44 C ro p C h e m i c a l s (4) 4.77 I r r i g a t i o n L ab o r. (5) 4.50 M achinery: F u e l p O i l , R e p a irs (6) 31.73 P ick u p V a r i a b l e Cost (7) 3.50 M i s c e l l a n e o u s Expense (8) 13.79 I n t e r e s t on O p e r a t i n g C a p i t a l (9) 2.96 M a c h i n e r y Labor (10) 1 5 .8 2 TOTAL VARIABLE COSTS (11) $ 1 1 5 .2 7 RETURNS OVER VARIABLE COST (12) $ 1 2 4 .7 3 Y ield (4 t o n s x $ 6 0 .0 0 ) VARIABLE COSTS B a s e d on d a t a f r o m G r i f f i t h , S c h a e f e r and L u f t 9.02 (1978) 119. T able 17. I r r i g a t e d A l f a l f a f o r S u b - b a s i n s 6 , 8 , and 9 . RETURNS (I) $2 4 0 .0 0 Stand E s ta b lis h m e n t (2) $ F ertilizer (3) 19.01 Crop C h e m i c a l s (4) 4.47 Custom S t a c k (5) 23.40 I r r i g a t i o n Labor (6) 6.98 M achinery$ F u e l, O i l , R e p airs (7) 12.23 Pickup V a r i a b l e Cost (8) 5.59 M i s c e l l a n e o u s E x p en s e (9 ) 7.35 Twine (10) 4.96 I n t e r e s t on O p e r a t i n g C a p i t a l (11) 1.70 M a c h i n e r y Labor (12) 7.62 TOTAL VARIABLE COSTS (13) $ 1 0 3 .1 5 RETURN OVER VARIABLE COST (1 4 ) $ 1 3 6 .8 5 Y ield (4 t o n s x $ 6 0 .0 0 ) VARIABLE COSTS and A p p l i c a t i o n B ased on d a t a fro m S c h a e f e r , G r i f f i t h and L u f t 9.84 (1978). 120 T a b l e 18. I r r i g a t e d Corn f o r G r a i n f o r A l l S u b - b a s i n s . RETURNS (I) $325.00 S eed ( 1 6 . 7 l b . x $ 1 . 0 5 / l b . ) (2) $ 17.53 F e r t i l i z e r and A p p l i c a t i o n (3) 38.40 C ro p C h e m i c a l s (4) 11.25 Custom H i r e (5) 55.00 (6) 6.00 . (7) 47.59 Pickup V a r ia b l e C osts (8) 5.00 M i s c e l l a n e o u s E x p en s e (9) 13.19 I n t e r e s t bn O p e r a tin g C a p i t a l (10) 7.22 M achinery Labor (11) 24.80 TOTAL VARIABLE COSTS (12) $225.98 RETURN OVER VARIABLE COST (1 3 ) $ 99.02 Y ield (100 bu. x $3.25) VARIABLE COSTS (Corn D r y i n g ) I r r i g a t i o n Labor M achinery: F u e l, O i l , R e p a ir s ( 6 . 2 h r . x $ 4 .0 0 ) B a s e d on d a t a f r o m F o g l e and L u f t (1980). 121 T a b l e 19 . I r r i g a t e d F eed B a r l e y f o r A l l S u b - b a s i n s . RETURNS Y ield (80 b u . x $ 2 . 0 0 ) (I) $1 6 0 .0 0 (2) $ VARIABLE COSTS Seed (90 l b . @ $4.50/bu.) 8.46 F e r t i l i z e r and A p p l i c a t i o n (3) 24.50 Crop C h e m i c a l s (4) 3.25 I r r i g a t i o n L ab o r (5) 4.00 M achinery: F u e l, O i l , R e p a irs (6) 26.07 Pickup V a r i a b l e Cost (7) 5.00 M i s c e l l a n e o u s Expense (8) 7.82 I n t e r e s t on O p e r a t i n g C a p i t a l (9) 3.17 (10) 17.87 TOTAL VARIABLE COSTS (11) $1 0 0 .1 4 RETURN (12) $ 59.86 M a c h i n e r y Labor (4.47 h r . x $4.00) OVER VARIABLE COST B a s e d on d a t a f r o m F o g l e and L u f t (1980). 122 T able 20. I r r i g a t e d B e an s f o r A l l S u b - b a s i n s . RETURNS (I) $ 4 6 0 .0 0 Seed (50 l b . x $48 . 0 0 / c w t . ) (2) $ 24.00 F e r t i l i z e r and A p p l i c a t i o n (3) 11.10 Crop C hem icals (4) 4.12 I r r i g a t i o n L ab o r (5) 6.40 M achinery: F u e l , O i l , R e p a irs (6) 60.09 Pickup V a r ia b le Cost (7) 5.00 M i s c e l l a n e o u s Expense (8) 1 0 .9 5 I n t e r e s t on O p e r a t i n g C a p i t a l (9) 4.61 (10) 30.32 TOTAL VARIABLE COSTS (11) $ 1 5 6 .5 9 RETURN OVER VARIABLE COST (12) $303.41 Y ield (20 cwto x $ 2 3 .0 0 ) VARIABLE COSTS M a c h i n e r y Labor (7.58 h r . x $4.00) B a s e d on d a t a fr o m F o g l e and L u f t (1980). 123 T able 21. I r r i g a t e d Sugar B e e ts f o r A ll Sub- b a s i n s . (I) $ 5 7 6 .0 0 Seed ( 2 . 1 l b . x $ 9 . 5 0 / l b . ) (2) $ 19.95 F e r t i l i z e r and A p p l i c a t i o n (3) 58.25 C ro p C h e m i c a l s (4) 9.45 Custom H i r e (5) to RETURNS I r r i g a t i o n Labor (6) 11.40 M achinery: F u e l, O i l , R e p a ir s (7) 93.42 Pickup V a r i a b l e Cost (8) 5.00 M i s c e l l a n e o u s E x p en s e (9 ) 20.75 I n t e r e s t on O p e r a t i n g C a p i t a l (10) 7.64 M achinery Labor (11) 43.73 TOTAL VARIABLE COSTS (12) $293.59 RETURN OVER VARIABLE COST (13) $ 282.41 Y ield (18 t o n x $ 3 2 .0 0 ) (Hbe B e e t s ) ( 1 0 . 9 3 h r . x $ 4 .00) B a s e d on d a t a f r o m F o g l e and L u f t (1980) O O VARIABLE COSTS 124 T able 22. I r r i g a t e d Corn S i l a g e f o r A l l S u b - b a s i n s . (I) $ 3 6 0 .0 0 Seed ( 1 6 . 7 l b . x $ 1 . 0 5 / l b . ) (2) $ 1 7 .5 3 F e r t i l i z e r and A p p l i c a t i o n (3) CO CO RETURNS Crop C h e m i c a l s (4 ) 11.25 I r r i g a t i o n L ab o r (5) 6.00 M achinery; F u e l f O i l , R ep airs (6) 5 6 .0 5 Pickup V a r ia b le Cost (7) 5.00 M i s c e l l a n e o u s E x p en se (8) 1 2 .1 8 I n t e r e s t on O p e r a t i n g C a p i t a l (9) 7.47 (10) 27.64 TOTAL VARIABLE COSTS (11) $ 1 8 1 .5 2 RETURN OVER VARIABLE COST (12) $1 7 8 .4 8 Y ield (20 t o n x $ 1 8 .0 0 ) M a c h i n e r y Labor ( 6 . 9 1 h r . x $ 4 .0 0 ) B a s e d on d a t a f r o m F o g l e and L u f t (1980). O =g& VARIABLE COSTS 125 APPENDIX B NET IRRIGATION REQUIREMENTS 126 Table 23. C l i m a t i c . Zones f o r th e Nine S u b - b a s in s . C l i m a t i c Zone S u b -b a sin s 1 T a b le 24. Month 5 ,6 ,7 and 8 2 , 2 , 3, 4 and 9 3 . I N et I r r i g a t i o n R e q u ir e m e n ts in a c r e - f e e t ) . A lfalfa B e an s (May t o Sep tem b er S u g a r Corn Corn B eets S i l a g e G rain P a s tu r e B arley C l i m a t i c Zone I M j J A S .23 .33 .57 .47 .23 .0 4 .06 .24 .54 .24 .19 .55 .56 .28 .03 .12 .47 .47 .17 .15 .38 .48 .04 .18 .25 .46 .40 .20 .32 .32 .12 .33 : 46 .05 .16 .22 .42 .36 .17 .28 .28 .04 .03 .14 .39 .35 .15 .25 .25 .04 „05 C l i m a t i c Zone 2 M J J A S .20 .03 .29 .52 .43 .18 o21 .54 .27 .05 .16 .52 .52 .23 .02 .10 .43 .43 .14 C l i m a t i c Zone 3 M J J A S .16 .27 .48 .39 .15 .04 .15 .47 .46 .19 127 APPENDIX C CROPPING PATTERNS Table 25. C rops Cropping Patterns a nd the Pl and P2 I 2 3 1 4 7 ,0 2 2 1 7 ,438 5 2 ,2 4 9 by Sub - b a s i n for the Scenarios (acres). S u b -b asin s 5 4 6 Basic Model 8 7 (Bi) 9 B arley A lfa lfa Hay O t h e r H ay 6 5 ,8 0 6 P astu re S ugar B ee ts 1 ,1 8 6 6 ,9 2 1 1 5 ,1 1 8 8 ,0 6 7 Corn 3,367 3 ,118 794 1 ,1 1 7 1 1 ,6 3 5 2 ,547 498 16 ,4 6 4 16,8 4 7 8 ,963 5 0 ,3 1 0 3 ,8 8 6 196 1,614 128 5 0 ,5 0 9 C orn S i l a g e Beans 7 ,174 Table 26. C rops Cropping Patterns by Sub-basin S u b -b asin s 5 i 2 3 4 147,0 2 2 8 3 ,2 4 4 6 5 ,6 4 1 5 2 ,2 4 9 1 ,186 6 ,9 2 1 1 5 ,1 1 8 8 ,0 6 7 for t h e El S c e n a r i o 6 9 8 7 (acres). B arley A lfa lfa H ay O t h e r H ay P astu re Sugar B eets Beans C o rn 5 0 ,5 0 9 S ilag e 3 ,367 10,613 3 ,118 794 1 ,117 1 1 ,6 3 5 2 ,547 498 1 6 ,4 6 4 1 6 ,8 4 7 1 0 ,5 7 7 5 0 ,3 1 0 196 3 ,886 129 Com 7 ,174 27. Table C rops C r o p p i n g P a t t e r n s by Scenarios (acres). I 2 Sub-basin 3 4 S u b -b asin s 5 for the 6 E2 and E3 8 7 9 B arley A lfa lfa H ay 1 4 7 ,0 2 2 8 3 ,2 4 4 7 6 ,2 5 4 5 2 ,249 1 ,186 6 ,9 2 1 1 5 ,1 1 8 8 ,0 6 7 O t h e r Hay P astu re Sugar B eets C orn 3 ,3 6 7 3 ,1 1 8 7 94 1 ,1 1 7 1 1 ,635 2 ,547 498 1 6 ,4 6 4 1 6 ,847 1 0 ,577 5 0 ,3 1 0 196 3 ,886 130 5 0 ,509 C orn S i l a g e Beans 7 ,174 Table 28. C rops Cropping I Patterns 2 3 by Sub-basin S u b -b asin s 5 4 for t h e Dl S c e n a r i o 6 9 8 7 (acres). B arley A lfa lfa Hay 1 4 7 ,0 2 2 2 8 ,0 6 8 5 2 ,2 4 9 1 5 ,1 1 8 8 ,067 8 3 ,2 4 4 O t h e r H ay P astu re Sugar B eets 1 ,1 8 6 6 ,9 2 1 C orn 3 ,367 3 ,1 1 8 4 8 ,1 8 6 794 1 ,1 1 7 1 1 ,6 3 5 2 ,547 498 1 6 ,464 16,8 4 7 6 ,692 5 0 ,3 1 0 3 ,8 8 6 196 3 ,885 131 5 0 ,5 0 9 C orn S i l a g e B eans 7 ,1 7 4 Table 29. Cropping Patterns by Sub-basin for th e D2 Scenario (acres). Sub-basins Crops I 2 3 5 4 6 8 7 9 Barley Alfalfa Hay Other Hay 5 2 ,2 4 9 8 ,3 3 5 1 3 3 ,0 9 7 Pasture Sugar Beets 1 ,186 6 ,9 2 1 3,367 3 ,118 7 ,1 7 4 5 0 ,5 0 9 794 1 ,117 1 1 ,6 3 5 2 ,547 498 16,4 6 4 16 ,8 4 7 4 ,580 5 0 ,3 1 0 3 ,886 196 5 ,9 9 7 132 Corn 8 ,067 7 6 ,2 5 4 Corn Silage Beans 1 5 ,118 Table 30. C rops Cropping Patterns I 2 by Sub-basin S u b -b asin s 5 3 4 8 8 ,8 7 6 6 0 ,7 1 9 1 5 ,1 1 8 8 ,0 6 7 for the Al S cenario 6 8 7 (acres). 9 Barley Alfalfa Hay 167,6 0 4 O t h e r Hay 9 6 ,2 2 6 P a stu re S ugar B ee ts 1,186 6 ,921 C orn 3 ,367 3 ,118 519 794 1 ,117 1 3 ,2 9 7 2 ,547 498 1 6 ,4 6 4 19,6 1 8 9 ,2 0 2 6 0 ,2 0 5 196 3 ,8 8 6 2 ,8 7 9 133 5 8 ,6 6 3 C orn S i l a g e Beans 7 ,174 Table C rops 31. Cropping I 2 Patterns 3 by Sub-basin S u b -b asin s 5 4 for t h e A 2 6 Scenario 9 8 7 (acres). B arley A lfa lfa Hay 1 8 8 ,1 8 3 7 8 ,1 1 1 6 9 ,1 8 8 1 5 ,1 1 8 8 ,0 6 7 1 0 9 ,2 0 7 O t h e r Hay P a stu re Sugar B eets 1 ,186 6 ,9 2 1 6 6 ,8 1 5 C orn S i l a g e C orn 3 ,367 3 ,1 1 8 2 4 ,4 2 3 794 1 ,1 1 7 1 4 ,9 6 0 2 ,547 498 1 6 ,4 6 4 2 2 ,3 8 8 9 ,4 4 1 7 0 ,0 9 9 3,886 196 4 ,1 4 4 134 Beans 7 ,1 7 4 Table 32. C rops Cropping Patterns i 2 3 by Sub-basin S u b -b asin s 5 4 for t h e A 3 6 Scenario 9 8 7 (acres). B arley A lfa lfa Hay 216,1 5 1 6 3 ,4 8 1 8 0 ,6 9 8 1 5 ,1 1 8 8 ,0 6 7 126,8 4 9 O t h e r Hay P astu re Sugar B eets Beans C orn 6 ,9 2 1 7 ,174 7 7 ,8 4 5 S ilag e 3,367 3 ,118 5 6 ,9 0 9 794 1 ,117 1 7 ,219 2 ,547 498 1 6 ,4 6 4 2 6 ,1 5 3 9 ,765 8 3 ,545 3 ,8 8 6 196 5 ,8 6 4 135 Com 1 ,186 REFERENCES. CITED 137 R e fe r e n c e s C ited A n d e r so n , Raymond L. 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