Sensitivity of Oregon's Cascade Lake s to Acid Precipitatio n by Peter 0 . Nelso n Gregory K . Delwich e Water . Resources Research Institut e Oregon State Universit y Corvallis, Orego n WRRI-8, 5 September 1983 SENSITIVITY OF OREGON'S CASCADE LAKE S TO ACID PRECIPITATION by Peter O . Nelson and Gregory K . Delwich e Civil Engineering Department, Oregon State Universit y Final Technical Completion Repor t for Project No . A-061-ORE to United States Department of the Interio r Washington, D .C . 2024 0 Project Sponsored by : Water Resources Research Institut e Oregon State Universit y Corvallis, Oregon 9733 1 The research upon which this report is based was financed in part by the U .S . Department of the Interior, Washington, D .C . (Project No . A-061-ORE), a s authorized by the Water Research and Development Act of 1978, P .L . 95-467 . Contents of this publication do not necessarily reflect the views an d policies of the U .S . Department of the Interior, nor does mention of trad e names or commercial products constitute their endorsement or recommendatio n for use by the United States Government . WRRI-85 September 1983 ABSTRACT A study of 63 Oregon Cascade lakes was conducted in 1982 to determin e their susceptibility to acidification and to assess the extent o f anthropogenic acidification that may have occurred to date . The study also established baseline data for important chemical parameters against whic h possible impacts could later be assessed and for comparison to dilut e acidified lakes of similar geology as an aid in data interpretation . Th e sampled lakes typically were located in forested watersheds at elevations o f 1000 to 2,000 meters . Geology of this study area is predominantly volcanic . Of the 63 lakes sampled in this study, 55 lakes were grab-sampled on e time each from shore or from a boat . The remaining 8 lakes were sampled 3 times each between July and October 1982 to gain an understanding of th e temporal fluctuations in their water chemistry . Grab samples were taken fro m shore on three of these lakes . The remaining five lakes were sampled from a boat at various depths within their water columns . Temperature, pH , dissolved oxygen and light intensity profiles were also obtained for thes e lakes . All of the lake samples were analyzed for pH, conductivity, alkalinity , calcium, magnesium, sodium, potassium, dissolved silica, chloride an d sulfate . Major ion balances were calculated . Analyses for total organi c carbon, fluoride and aluminum were also performed on some samples . Particular emphasis was place upon developing an understanding of th e predominant buffer system in the lakes . The carbonate system, inorgani c aluminum, and weak organic acids all have been reported to be significan t buffer systems in other lakes of igneous geologic origin . The investigated lakes studied can be characterized as having a n extremely dilute ionic composition . The average conductivity was 17 . 0 umhos/cm . The average laboratory-equilibrated pH was 6 .96 ; the range wa s 5 .83 to 7 .91 . Alkalinities ranged from 1 to 527 ueq/l, with an average o f 137 .6 ueq/l . Twenty-five lakes had alkalinities of less than 50' ueq/l whil e 26 more had alkalinities less than 250 ueq/l and 11 of the remaining 12 lake s had alkalinites less than 500 ueq/l . Nearly all of the lakes sampled in thi s study are susceptible to acidification, according to recently propose d criteria . Calcium was the major cation (36%) and bicarbonate was the major anio n (82%) present in the lakes studied . Aluminum concentrations were extremel y low (generally less than 20 uq/l) ; sulfate concentrations were also quite low (generally less than 300 ug/l) . -Total' ion balances generally agreed withi n 10% (cation vs . an.ion) . The dominant buffer system in the Oregon lakes was the carbonate system . The extremely low aluminum and total organic carbon concentrations indicat e the minor contribution of aluminum hydrolysis species and weak organic acid s to the overall acid neutralizing capacity of these waters . The ratio o f calcium to bicarbonate (equivalent basis) and the low dissolved aluminum an d sulfate concentrations clearly indicate that anthropogenic acidification i s undetectable to date in Oregon's Cascade lakes . It was concluded that Oregon does not generally seem to have an aci d precipitation problem at present . However, the lakes of the Oregon Cascade s are extremely susceptible to acidification and could be rapidly impacted i f acid precipitation were to occur . The lakes may serve as in chemica l benchmark against which acidified lakes of similar geology can be compared . FOREWORD The Water Resources Research Institute, located on the Oregon State . University campus, serves the State of Oregon . The Institute fosters , encourages and facilitates water resources research aed education inveLvi.n g all aspects of the quality and quantity of water available for befi .cia l use . The Institute administers and coordinates statewide aiid regi ;oaal, programs of multidisciplinary research in water and related land re r p ces. . The Institute provides a necessary communications and coo .r~dination lin k between the agencies of local, state and federal government, as wel .i as th e private sector, and the broad research community at universities in the stat e on matters of water-related research . The Institute also coordinates th e inter-disciplinary program of graduate education in water resources at Oregon State University . It is Institute policy to make available the results of significan t water-related research conducted in Oregon's universities and colleges . Th e Institute neither endorses nor rejects the findings of the authors of suc h research . It does recommend careful consideration of the accumulated fact s by those concerned with the solution of water-related problems . ACKNOWLEDGEMENT S The authors wish to ackno w.;kedge the extensive help of Donald B . Miller , Research Associate, in condnoting the laboratory measurements . We also than k Anne Chung, Jeff Dresser and Alan Ratcliff, graduate students i n environmental engineering, for assistance with the Iaborlatory work . Davi d Nichol, undergraduate civil engineering student, is thanked for his care i n the final preparation of figures and tables and in making the regressio n analyses . Laurie Delwiche, field aid, is thanked for her assistance i n sample collection at most of the lakes . ii TABLE OF CONTENTS P List of Figures . .y . iv . . . iv Introduction . . . 1 Research Procedures . . . 3 . . . . . . 3 4 . . . 9 . . . . . . 9 9 List of Tables . . y Sampling Methodology Analytical Techniques Results of Analyses Overview of Results Detailed Results Discussion of Results . 23 . . . . . . . . . 23 24 26 Conclusions . . . 33 References . .. 39 Appendices . . . 39 Limnological Data for Studied Cascade Lakes . . . . . Chemical Data for Studied Cascade Lakes . . . . . . . Discussion of Experimentation in Laborator y . . . Techniques 41 45 Regional, Temporal, and Spatial Trend s in Water Chemistry General Acidification Sensitivity Criteria Applicability of Acidification Sensitivity Models . A. B. C. . . 51 LIST OF FIGURE S 1 . Study Area, Oregon Cascade Lakes . 2 2. Bar Graph of Average Concentrations for Major Cations an d Anions for the 63 Cascade Lakes . 11 3. Alkalinity Frequency Distribution for the 63 Cascade Lakes . 12 4. pH Frequency Distributions for the 63 Cascade Lakes . . 13 5. Relationship Between Alkalinity and Lab pH fo r the 63 Cascade Lakes .- 17 Titration Curves for Selected Cascade Lakes o f Differing Alkalinity . 25 Calcium-pH Diagrams for Oregon Cascade Lakes in Compariso n with Washington Cascade Lakes . 30 6. 7. . . . LIST OF TABLES Page 1. Data Summary for Oregon Cascade Lakes 2. Correlations of Major Cations and Anions wit h Conductivity and pH, and Selected Cross-Correlations 3. Alkalinity-Calcium Relations for Lakes fro m Various Regions iv 10 . , . . 14 29 INTRODUCTION Acidification of lakes and streams has been identified as a serious wate r quality problem in the northeastern United States (Driscoll, 1980) , southeastern Canada (Dillon et al ., 1980) and Scandinavia (Wright an d Henricksen, 1978) . Acid precipitation has been recently reported in th e central Washington Cascades, but concomitant lake acidification has apparentl y not occurred to date (Logan et al .,1982) . Based on Iimited data, acid precipitation does not appear to be a genera l problem in the Oregon Cascades (Powers and Rambo, 1981 .U ; .S . Geologica l Survey, 1981) . There are no major sources of sulfur dioxide emissions i n western Oregon ; however, automobiles in the heavily populated Willamett e Valley and metropolitan Portland area represent a source of oxides o f nitrogen . Such emissions have been indicated as the predominant causes o f acid precipitation downwind of the Los Angeles area (Liljestrand and Morgan , 1978) . Acid precipitation was recorded in Oregon immediately before an d following the June 12, 1980 eruption of Mount St . Helens . Volcanic ash wa s found in precipitation collectors following this eruption . Southerly wind s which were blowing at the time of this eruption are, however, relatively rar e in this area . There were three primary objectives of this study : (1) . to determine th e sensitivity of Oregon's Cascade lakes to acidification ; (2) to assess th e extent of anthropogenic acidification that may have occurred to date ; and (3 ) to establish baseline data for important chemical parameters against whic h possible impacts could later be assessed and for comparison to dilut e acidified lakes of similar geology as an aid In data interpretation . Sixty-three lakes in the Oregon Cascades, shown in Figure 1, were sample d between July and October 1982 . The Oregon Cascade Range rams approximately 7 0 km east of the Willamette Valley and Portland, and downwind of prevailin g westerly weather patterns . The lakes sampled in this study typically wer e located in forested watersheds at elevations between 1,000 anal 2,000 meters . The lakes and streams of the Oregon Cascades have geological, physical an d chemical characteristics typical of waters sensitive to acidic imputs . Suc h lakes are generally shallow, have small watershed/surface area ratios, low productivity and short residence times . Watersheds are characterized b y poorly developed seils, high .aamual precipitation and short soil/wate r retention times . Bedrock is geaeraliy siliceous, of igneous origin, an d highly resistant to chemical weathering . These charcteristics have bee n proposed by others as typical of areas with acid-sensitive lakes (Schofield , 1976 ; Wright and Gjessing, 1976 ; Driscoll, 1980 and Hendrey et al ., 1980) . Although water chemistry data for Oregon's Cascade lakes is generally limited , 60 of 80 lakes sampled in 1975 by Shulters (1975) had alkalinities less tha n 200 ueq/l, indicating the extreme sensitivity of these lakes to acidification . STATE OF OREGO N ENLARC'EU AREA OF HIGH CASCADES OLALLI E MONOD HORSESHOE GIBSO N BREITENBUS H F I RST HEAD LOWE R F I SH SHEEP WAL L AVERILL RED BROOK JUDE RUSS 7 JORN RED BUTT E SANTIAM DUFF Y MOW I CH BLUE, ROUN D SCOU T CLEA R THREE CREEK S LAVA CAMP, SCOTT TODD DEVILS SPARK S ELK HOSMER LAVA L. LAVA LUCKY K I WA WAHANNA TORRE Y WHI G U. RI GDO N L. RI GOON BETT Y GOLD U. MARILYN L. MARILYN ODELL -J ~ SUMMIT .~~ CULTUS, L. CULTU S CHARLETO N DAVI S CRESCEN T Figure 1 . Study Area, Oregon Cascade Lakes . .41 2 RESEARCH PROCEDURE S Sampling Methodolog y Water samples were collected and stored in one-liter linear polyethylene sample bottles . These bottles were acid washed with nitric acid an d copiously rinsed three times with distilled water and twice with double distilled deionized water . Samples were placed on ice after collection an d were stored at 4 0 C upon returning to the laboratory . All samples wer e filtered through 0 .45 um millipore filters immediately upon returning to th e laboratory and prior to performing any analyses . Special care was taken i n the laboratory to avoid contamination of water samples while performin g analyses . Glassware and plasticware were acid washed and copiously rinse d several times, first with distilled water and then with double-distille d deionized water . Of the 63 lakes sampled in this study, 53 lakes were grab-sampled on e time each from shore . Eight of the remaining ten lakes were sampled thre e times between July and October 1982 to investigate temporal fluctuations i n their water chemistry . Grab samples were taken from shore on three of thes e lakes :- Betty, Lucky and Summit (Mt . Hood National Forest) . The fiv e remaining temporally sampled lakes, Waldo, Summit (Deschutes Nationa l Forest), Bull Run, Lost andGjallie, were sampled by boat at various depth s within their water columns 'to Study spatial variations in water chemistry . Temperature, dissolved oxygen and light intensity profiles were also obtaine d for these lakes . Finally, the remaining two lakes (Blue and Elk) wer e sampled by boat one time during the summer at various locations within thei r water columns . Water samples from the 56 grab-sampled lakes were collected by holding a m open sample bottle approximately 0 .3 m below the water surface adjacent t o the shoreline . Sample bottles were rinsed with lake water approximately 4 t o 5 times before the final water sample was collected . Special care was taken to avoid sampling lakes im littoral areas where physical characteristic s differed from the general shoreline zone of the lake (i .e ., areas of inflow , swampy areas of an otherwise non-swampy lake, or areas of obvious huma n impact) . Temperature and in-situ pH data were also collected at the time o f sample collection . For the five lakes sampled by boat at various depths, the water sample s were collected with a 2-liter water sampler . Sample bottles were rinsed 3 t o 4 times with water from the sampler before the sample bottle was filled wit h the final water sample . A small amount of the water from the sampler was . placed in a rinsed 125 ml plastic bottle and the temperature and "in-situ " pH were immediately taken and recorded . 3 It should be noted that the possibility of spatial differences in wate r chemistry exists in lakes that were grab-sampled from shore . Ideally, th e best possible situation would be to collect samples from the center of eac h lake 1 to 2 meters below the water surface . Such a sampling procedure weul d be both time-consuming and impractical for lakes without automobile amass . Most of the lakes that were shore sampled, however, were small and/er too shallow to be strongly stratified . Hence, it would be expected that thes e lakes would have relatively homogeneous water chemistry, as they could b e assumed to be completely mixed . in the larger lakes that were temperally an d spatially sampled, there was little or no variation in the data from th e various water'samples . Larson and Donaldson (1970) also reported a remarkable lack of spatial variation in water chemistry for Waldo Lake , Oregon's second largest lake . This lack of spatial variation in wate r chemistry was also reflected in the data collected In this study ; our dat a and that by Larson, and Donaldson indicate that the water chemistry of shor e samples is generally representative of the water chemistry of the entir e lake . Analytical Technique s All water samples collected were analyzed for laboratory-equilibrated pH , conductivity, alkalinity, metals (calcium, magnesium, potassium, s ium .) , dissolved silica, chloride and sulfate . Analyses for alwminum ; tota l dissolved organic carbon and fluoride were also performed on some samples. In-situ pH data were collected at the sample site . In-situ pH (Field pH) : Field pH measurements were made with an Orion 211 digital pH mete r equipped with an Orion 91-06 combination gel-filled electrode . This pH mete r and electrode system is capable of being read to hundredths of a pH unit wit h resolution of 0 .005 pH units (Orion, 1981) . The pH meter was standardized i n the field at pH = 7 and the slope calibrated at pH = 4 in the lab . Specia l care was taken to calibrate the meter to the exact pH of the buffer at th e given buffer temperature, as buffer pH is a function of temperature . For lakes that were shore-sampled, field pH (or in-situ pH) was taken by holdin g the probe in the lake with the sensing bulb approximately 6 cm below th e water surface in deep enough water such that the lake bottom was at least 5 cm below the bottom of the probe . For lakes that were sampled by boat, fiel d pH data were collected by placing some of the sample in a rinsed 125 m l narrow mouth plastic bottle immediately after collection and recording the p H of the sample in the bottle, as described earlier . In both cases, field p H values were recorded only after the pH meter was stable for at least on e minute . Equilibration time was typically 3 to 10 minutes . Laboratory-Equilibrated pH (Lab pH) : Laboratory pH measurements were made with an Orion 601A digital pH mete r equipped with a Ross 81-02 glass combination electrode . This pH meter i s 4 capable of being read to the nearest hundredth of a pH unit with a relativ e accuracy of 0 .01 pH units (Orion, 1977A) . The pH meter was calibrated a t pH = 7 and the slope calibrated at pH = 4 immediately prior to use . Spe€Ua t care was taken to calibrate the meter to the exact pH of the buffer at th e given buffer temperature . To measure lab pH, approximately 100 ml of th e water sample was placed in a 150 ml beaker and stirred using a magneti c stirrer . An insulating pad was placed between the beaker and stirrin g mechanism to minimize heat transfer to the sample from the stirrer . Lab pH values were recorded only after the pH was stable for at least 2 to 3 minutes . Equilibration time was typically 30 to 90 minutes . This lon g equilibration time probably results from pH change induce d, by equilibratio n of the water sample with atmospheric carbon dioxide in the laboratory . Conductivity : Conductivity measurements were performed using a Labline Lectro-mhe-mete r Model MC-1 Mark IV cell-type conductivity meter . Conductivity measurement s were performed within 24 hours after returning from the field . Conductivities were temperature corrected so that the data reflec t conductivity in umhos/cm at 25 0 C . Temperature corrections were made using an averaged Linear correction based on conductivity analyses performed a t various temperatures on two water samples--an extremely dilute sample ( 3 umho/cm) and a moderately dilute sample (15 umho/cm) . Alkalinity (Acid Neutralizing Capacity) : Alkalinity, or acid neutralizing capacity, was determine d potentiometrically by titrating a 50 ml water sample with 0 .05 N HCI using a 10-100 ul adjustable micro-pipettor . Samples were stirred with a magneti c stirrer apparatus during the titration . The Gran technique was used for titration end point identification (Gran, 1952 ; Stumm and Morgan, 1981) . Approximately 5 to 10 incremental points of volume-of-acid-added vs . pH wer e linearly regressed using the Gran function . The regressed points all had p H values of 4 to 5 . Analyses were performed in duplicate (or more) and nearl y always agreed within 5% . Standards with alkalinities of 100 meq/l wer e titrated frequently for quality assurance . These standards always agree d within 5% and usually within 2% . Alkalinity analyses were performed within 1 to 5 days of sample collection . Metals : Analyses for sodium, potassium, magnesium and calcium were performe d using a Perkin-Elmer Model 360 flame atomic absorption spectroph ..tometer . Procedural techniques used were in accordance with Perkin Elmer, (1982) an d Standard Methods (1980) . To eliminate inferences associated with th e ionization of alkaline-earth metals, 2 .5 percent lanthanum in 50% concentrated hydrochloric acid was added to the samples prior to analyses fo r calcium and magnesium, in accordance with EPA (1974) . All samples had bee n filtered immediately after returning from the field ; hence, the metals dat a reflect dissolved concentrations . Detection limits for calcium, magnesium , sodium and potassium were all approximately 0 .03 mg/I . The accuracy of th e calcium data was verified by EDTA tttrations on selected samples i n accordance with Standard Methods (1980) . 5 Dissolved Silica : Dissolved silica analyses were performed using the keterepoiy-blue metho d (Standard Methods, 1980) . A Bausch and Lomb Spectronic 80 spectr®photernete r was used for this colorimetric analysis . The detection limit of this meihed was 0 .02 mg/I SI02 . Chloride : Chloride Ion concentrations were determined by titration with mercuri c nitrate using diphenylcarbazone to indicate the titration endpoint and xylem e cyanol FF as a pH Indicator (Standard Methods, 1980) . The 0 .0141 N mercuri c nitrate was added with a 10-100 ul adjustable pipettor . The detection limi t of this method was 0 .05 mg/I Cl . Two other analytical methods for chloride were initially tried and foO .d to be unsuitable . An Orion chloride electrode with a double junction reference electrode was initially tried . This method of analysis was found t o be unsuitable for several reasons . There was an extremely long response tim e (>30 minutes) for each sample analyzed . Next, the lower limit of the linea r or Nernstian range for the electrode was 1 .75 mg/I CI . This concentration wa s significantly higher than the typical chloride concentrations eneoentered i n this study . Although using sufficient standards enabled the electrode to be used to measure concentrations below the Nernstian range, the procedwre wa s very time-consuming, as large numbers of standards were required . I n addition, when measuring chloride in a particular sample, there was a ver y significant carryover of chloride from the previous sample . Thus, th e chloride ion electrode was not used for the above reasons . A p..oten .tiometri c titration for chloride using silver nitrate could have been used, but thi s method was also very time-consuming and impractical for processing larg e numbers of samples . The other analytical method that was found to be unsuitabLe was th e argentometric method (Standard Methods, 1980) . In this method, potassiu m chromate Indicates the end point of a silver nitrate titration of the sample . During the titration, silver chloride is preferentially precipitated befor e the end point, which is indicated by the formation of red silver chromate . This end point was, however, difficult to detect consistently, as the colo r change was very gradual . Hence, this method was also found to be unsuitable . Sulfate : Sulfate analyses were performed using a modification of the turb i d imetr i c method (Standard Methods, 1980) . A Hach 2100-A turbidimeter was used in thi s analysis . The tu .r- b i d i.metr i c method involves adding barium chloride crystal s to the sample, resulting in the precipitation of less-soluble barium sulfate . A conditioning reagant containing glycerol, isopropyl alcoh®l, hydrochlori c acid and sodium chloride is also added to assure formation of uniform-size d barium sulfate crystals . This reagant, however, adds a background turbidit y which is often much greater than the turbidity of the barium sulfat e suspension, especially in a dilute water sample . Hence, at low 6 i concentrations, the precision of the data collected using this method is poor . In addition, the detection limit is also quite high, at 1 .0 mg/I SO4, becaus e of the turbidity of the conditioning reagent . Therefore, to increase the precision of this method and lower th e detection limit, the con .dItioning reagant was not used . This change lowere d the detection limit to <0 .1 mg/I S04 and greatly increased reproducibility . Although the standard curve, after making this change, was more exponentia l then linear, enough standards were used to bracket the range of sulfat e concentrations measured . This non-linearity is probably due to the formatio n of larger barium sulfate crystals at higher sulfate concentrations . Aluminum : Aluminum concentrations were determined colormetrically using a metho d developed by Barnes (1975) . After filtration through a 0 .45 um milliper e filter, 8-hydroxyquinoline was added to a 40 ml. aliquot of the water sample , forming a complex with the dissolved aluminum . This complex was immediatel y extracted with methyl-iso-butyl-ketone . The reliable detection limit of thi s method was 5 ug/l Al . Typical aluminum concentrations encountered in thi s study ranged from <5 to 25 ug/l Al . Total Organic Carbon : Total dissolved .argaw.io carbon concentrations were determined by measurin g the C02-infrared absorbance of the wet-oxidized dissolved organic carbon usin g an Oceanography International Carbon Analyzer . Samples were prepared an d organic carbon oxidized in accordance with the Oceanography Internationa l Carbon Analyzer Instruction Manual (1974) within 1 to 3 days after sampl e collection . Since samples were filtered through 0 .45 um mlliip .ore filte r prior to oxidation of organic carbon, the total organic eeneen.trat .i .on s reported are dissolved concentrations . The detection limit of this method wa s 0 .1 mg/l ; however, the reproducibility was about 75% of the mea n concentration . Hence, total organic carbon concentrations reported her e should be considered only as rough indicators of carbon concentrations . Typical total organic carbon concentrations found in this study were ‹x•0 .1 to 1 mg/l TOC . Fluoride : Fluoride analyses were performed using an Orion 96-09 Fluoride'Oembinatie n Electrode with an Orion 801A lonanalyzer . This meter is capable of being read to tenths of a millivolt . The analytical procedure used was in accordance with Orion (1977B) . The lower limit of the Nernstian or linear range for th+ e electrode is 200 ug/l F . In this study,, the lower end of the linear range wa s found to be 50 tog/I . The use of sufficient standards with concentration s below the linear limit allowed fluoride concentrations a& low as 1 .0 ug/l to be measured . At these low fluoride concentrations, equilibration time for th e electrode was 10 to . 20 minutes . Typical fluoride concentrations encountere d in this study were 1 to 10 ug/l F . TS (P, ANALYSES The detailed f i e l d and I aboredry data are presented I n B . This chapter gives a general explanation of the data . Append ices A a'm.d in addition to the analyses performed to achieve the primary objective s of this study, additional laboratory experiments were performed t o investigate (a) differences in analytical procedures used amon g acid-precipitation researchers and (b) inconsistencies in comparin g historical alkalinity data to recent data collected using Gran titration• t o determine the alkalinity titration end point . The results of thes e experiments are summarized in Appendix C . Over■4ew o!Result s The mean, median, standard deviation, and maximum and minimum values for the water quality parameters monitored in this study are summarized in Tabl e 1 . The lakes sampled in this study can be characterized as poorly baf, feced and having an extremely dilute ionic composition . The average cation/anio n ratio (equivalent basis) was 0 .99, with s = 0 .15 . Calcium constituted 36% o f the cations (equivalent basis), with sodium, maganesium and potassiu m representing the remaining 31, 26 and 7 percent, respectively . Bicarbonate constituted 82% of the anions, with chloride and sulfate representing th e remaining 15 and 3 percent, respectively . Figure 2 is a bar graph showin g the average concentration of major cations and anions for the 63 lake s monitored in this study . Frequency distributions for alkalinity, in-sit u (field) pH, and laboratory-equilibrated pH are shown in Figures 3 ant 4 . Th e alkalinity frequency distribution (Figure 3) shows that the greatest numbe r of lakes had alkalinities less than 25 ueq/I, with the few less-dilute Lake s inflating the overall average alkalinity . Cation concentrations and alkalinity were linearly correlated wit h conductivity ; an exponential relationship was found to . exist between thes e parameters and pH . Table 2 shows these correlations . The identifie d equations are presented in following text discussion . The lack of treads between chloride and sulfate as functions of conductivJty and pH may possibl y indicate that these ions are not released in significant concentrations b y mineral dissolution reactions (as are cations and alkalinity), but ar e present as the result of deposition of anthropoge.mic emissions and/or se a spray . Detailed Results, The mean, standard deviation, and maximum and minimum values (no t sea-salt corrected) for the water chemistry parameters monitored in thi s study are given in the following paragraphs . Also presented are the sea-sal t corrected correlations of each parameter with conductivity (COND) , alkalinity (ALK), and pH (based on concentrations in ueq/l) . A•shor t discussion of observations with respect to each parameter is als o. presented . 9 1 Table 1 . Data Summary for Oregon Cascade Lake s Parameter Lab pH Field pH COND, umhos/cm Alkalinity, ueq/l Ca, mg/I Mg, mg/I Na, mg/l K, mg/l S0 4 , mg/I Cl, mg/I -log, Pco 2 (field) -log, Pco(lab) 2 F, ug/I Al, ug/I TOC, mg/I SiO2, mg/l AVG'Ecat ., ueq/l AVG ueq/I Ecat ./EAn . an., Number of Lakes Mean 63 63 63 63 63 63 63 63 59 60 63 63 20 8 6 62 61 59 59 6 .96 6 .93 Standard Maxifnmm 61[njmmm Deviation 0 .59 0 .80 13 .95 135 .80 17 .03 137 .60 1 .16 0 .51 1 .13 1 .02 0 .49 0 .94 0 .33 0 .28 0 .62 0 .48 0 .47 0 .28 0 .83 3 .35 3 .36 0 .15 18 .10 16 .00 --- 11 .80 16 .00 < .10 7 .03 7 .27 168 .30 136 .40 172 .90 0 .99 142 .60 0 .15 10 7 .91 9 .51 57 .68 526 .70 3 .75 2 .00 3 .90 1 .27 2 ..1? t. 2 .43 3 .03 82 .30 56 .00 2 .80 26 .56 539 .40 578 .80 1 .30 5 .83 5 .47 2 .58 1 .0 5 0 .0 9 0 .0 3 0 .1 2 0 .0 4 0 .0 3 0 .3 0 5 .3 3 3 .99 <1 .0 0 <1 .0 0 < .1 0 0 .0 5 12 .7 0 18 .0 0 0 .39 /E . + 0 IV ) U SDV 1 JO e98WnN n r 11112MIMMEMEM 12MINEIMEMERIMBSOME 11IMIMERM 11MMEENIMMIM so m N U) ' -i .a sE>Iv -l dO U) 4- m U1 N a o JS8Wf1 N •r s- 4-) N m 0 G >) U C .-1 a) a)) LI_ 0l 0 0 W H IL a) Table 2 . Correlations of Major Cations and Anions with Conductivit y and pH, and Selected Cross-Correlation s Equation a Equation No . 4 7 10 14 19 22 24 26 28 5 8 11 15 20 23 25 27 29 6 9 12 13 16 21 Correlation Coefficient, r 2 ALK = -25 .65 + 9 .56 COND Ca = -1 .26 + 3 .51 COND Mg = -7 .65 + 2 .66 COND Na = -9 .15 + 2 .38 COND K= 4 .97 + 0 .41 COND SCAT = -14 .41 + 9 .00 COND S04 = 4 .50 + 0 .08 COND CI = 1 .57 + 2 .12 COND SI0 2 = -2 .69 + 6 .85 COND ALK = Ca = Mg = Na = K= ECAT = S04 = CI = SiO2 = COND = ALK = ALK = ALK = ALK = ALK = ALK = 0 .97 0 .88 0 .90 0 .7 6 0 .48 0 .96 0 .0 1 0 .3 4 0 .6 3 6 .96 (1077 ) exp (2 .63 pH) 1 .13 (10-4 ) 1 .21 (1 07 ) 4 .63 (10 6 ) 6 .59 (10) 1 .11 (10) 5 .54 (1 0 1 ) 3 .46 (1 0- ') 1 .06 (1 0 5 ) 4 .95 (107 ') -8 .66 -4 .33 7 .05 -5 .69 + + + + 27 .19 + 0 .84 + exp (1 .81 exp (2 .05 exp (2 .16 exp (1 .03 exp (1 .93 exp (0 .29 exp (4 .26 exp (2 .21 exp (1 .45 1 .05 pH) pH) pH) pH) pH) pH) pH) pH) pH) SCAT 2 .42 3 .32 1 .49 Ca Mg (Ca + Mg) 3 .21 Na 11 .38 K 0 .9 4 0 .83 0 .7 1 0 .7 8 0 .44 0 .86 0 .0 1 0 .21 0 .72 0 .84 0 .99 0 .87 0 .9 2 0 .95 0 .8 2 0 .49 a Units for all parameters are ueq/l, except COND (umho/cm) . All parameters are sea-salt corrected except Cl . 14 Conductivity : The average conductivity in the 63 Lakes studied was 17 .03 umhos/cm, wit h a high of 57 .7 umhos/cm, and a low of 2 .58 umhos/cm . The standard deviation was 13 .95 umhos/cm . The large standard deviation reflects the variability i n diluteness of the lakes sampled, while the extremely low mean conductivity i s indicative of the generally dilute water chemistry of Oregon's Cascade lakes . Strong linear correlations were found between conductivity and calcium , magnesium, sodium, potassium, silica and alkalinity (See following sections) . Such correlations would be expected, as conductivity is a measure of th e overall ionic composition of a water body . Conductivity increase d exponentially with both in-situ pH and laboratory pH . In contrast, Driscol l (1980) reported that conductivit[es of acidified Adirondock surface wate r increased with decreasing pH, reflecting the increased conductance of th e hydrogen ion at low pH values . When Driscoll's conductivities were correcte d for hydrogen ion conductance, however, conductivity then increased wit h increasing pH . Thus, the conductivity-pH relation for lakes of a give n region could be used as an indicator of anthropogenic acidification . The following linear regression between measured conductivity an d calculated ionic strength was obtained : I = 1 .28 (10 -5 ) COND (n = 59, r 2 = 0 .99) (1 ) Snoeyink and Jenkins (1980) report a somewhat similar expression : I = 1 .6 (10 -5 ) COND . When activity coefficients are calculated using th e average conductivity for the 63 lakes and the Debye-Huckel limiting law , coeffici•ekts of 0 .98 and 0 .93 were obtained for monovalent and divalent ions , respectively . Hence, the errors incurred by using concentrations i n calculations, instead of activities, are probably insignificant and withi n the analytical uncertainty of the data collected . pH : The average in-situ pH (field pH) of the 63 lakes was 6 .93, with a hig h of 9 .51 and a low of 5 .47 . The standard deviation was 0 .80 . The averag e laboratory-equilibrated pH was 6 .96, with a high of 7 .91 and a low of 5 .83 . The standard deviation was 0 .59 . The greater standard deviation in in-situ pH reflects the influences o f biological activity, wave action and temperature fluctuations on dissolve d carbon dioxide concentration . These influences were generally not present i n the laboratory, as biological activity was minimized with filtering th e sample and refrigerating it, and temperature fluctuations did . not exist . When laboratory pH is regressed as a function of field pH, the followin g expression is obtained : Lab pH = 0 .646 + 0 .91(Field pH) (n = 63, r 2 = 0 .82) 15 (2 ) When this regression is forced through the origin, the following expressio n is obtained : Lab pH = 1 .003(Field pH) (3 ) Thus, there was little deviation from a 1 :1 relationship between these parameters . Alkalinity : The average alkalinity for the 63 lakes was 13 .7 .6 ueq/l, with a high o f 526 .7 ueq/l and a low of 1 . .1 ueq/l . The med i ai alkalinity was -83 .9 ueq/l . The standard deviation was 135 .8 ueq/l . Figure 3 showed the distribution o f alkalinities among the 63 lakes studied . There -was a,Iimntar relation betwee n alkalinity and conductivity and an exponentl . al relation between alkalinit y and pH . A strong linear correlation was found betileen alkalinity and tota l cation concentration (equivalent basis) . These regressions are as follows : ALK = -25 .65 + 9 .56 COND (n =63, r 2 = 0 .97) (4 ) ALK = 6 .96 (10 7) exp (2 .63 pH) (n = 63, r 2 = .94) (5 ) ALK = -8 .66 + 1 .05 SCAT (n = 61, r 2 = 0 .99) (6) Figure 5 shows the relationship between alkalinity and lab pH . Th e relationship between alkalinity and pH for a solution saturated with carbo n dioxide is also shown . It is thus evident that the lakes sampled wer e generally supersaturated with carbon dioxide when lab pH was determined o r that additional weak acid buffering was present . This situation is discussed in detail in a following section titled "Predominant Buffer Systems" (it i s concluded in that section that the lakes were s .npers{turated and additiona l weak acid buffering was negligible) . Calcium : The average calcium concentration in the 63 lakes sampled was 1 .16 mg/I , with a high of 3 .75 mg/I and a low of 0 .09 mg/I . The standard deviation wa s 1 .02 mg/I . As mentioned earlier, strong linear correlations were foun d between calcium and both alkalinity and COND, while an exponentia l correlation was found between calcium and pH . These expressions are a s follows : Ca = -1 .26 + 3 .51 COND Ca = (n = 63, r 2 = 0 .88) 1 .13 (10 -4 ) exp (1 .81 pH) ALK = -4 .33 + 2 .42 Ca (n = 63, r 2 = 0 .83) (n = 63, r 2 = 0 .87) 16 (7 ) (8 ) (9 ) U,N r a 4) u) 3 4-3 N (7/Sn) Al I N 11V>I 1 V 17 A comparison of calcium-alkalinity relationships for lakes in differen t geographical areas is discussed in detail in a following section title d "Applicability of Acidification Sensitivity Models" . The lakes sampled i n this study had a significantly greater alkalinity-to-calcium ratio than mos t other dilute, non-acidified lakes (see Table 3) . This high ratio is probabl y due to large amounts of alkalinity associated with magnesium- , potassium- , and sodium-bearing minerals . Magnesium : The average magnesium concentration for the 63 lakes . was 0 .51 mg/I, wit h a high of 2 .00 mg/I and a low of 0 .03 mg/I . The standard deviation was 0 .4 9 mg/l . As mentioned earlier, strong linear correlations between magnesium an d both conductivity and alkalinity were found ; magnesium and pH wer e exponentially related . These expressions are as follows : Mg = -7 .65 + 2 .66 COND (n =63, r 2 = 0 .90) Mg = 1 .21 (10 5 ) exp (2 .05 pH) (n = 63, r 2 = 0 .71) ALK = 7 .05 + 3 .32 Mg (n = 63, r 2 =0 .92) (10 ) (11 ) (12 ) The regression for the sum of magnesium and calcium versus alkalinity i s as follows : ALK = -5 .69 + 1 .49 (Ca + Mg) (n = 63, r2 =0 .95) (13 ) Thus, significant amounts of alkalinity must be associated with dissolutio n of sodium- and potassium-bearing minerals, as the ratio of alkalinity t o calcium-plus-magnesium is still significantly greater than unity . Sodium : The average sodium concentration for the 63 lakes was 1 .13 mg/i, with a high of 3 .90 mg/I and a low of 0 .12 mg/l . The standard deviation was 0 .9 4 mg/I . Again, strong linear correlations. between sodium and both alkkal,init y and conductivity were-found ; sodium and pH were exponentially related . Thes e regressions are shown below ' Na = -9 .15 + 2 .38 COND (n = 63, r 2 =0 .7W,), Na = 4 .63 (10 -6 ) exp (2 .16 pH) (n = 63, r 2 = 0 .78) ALK = 27 .19 + 3 .21 Na (n = 63, r 2 = 0 .82) 18 (14 ) (15 ) (16 ) The regression between sodium and chloride (equivalent basis) was a s follows : (n = 58, r 2 = 0 .26) Na = 36 .9 + 0 .62 CI (17 ) or, forced through the origin : (18 ) Na = 1 .64 CI Hence, if chloride is assumed to be entirely the re wIt e" sea spray deposition, a varying but significant amount of sodium must be of watershe d origin . It would also seem that there is a significant amount of alkalinit y associated with this sodium of watershed origin . Potassium : The average potassium concentration was 0 .47 mg/I, with a high of 1 .27 A mg/I and a low of 0 .04 mg/I . The standard deviation was 0 .33 mg/I . somewhat weaker correlation was found between potassium and both alkalinit y and conductivity ; potassium and pH were also more weakly related . Thes e regressions are as follows : (n = 63, r 2 =0 ..48) ' (19 ) K = 6 .59 ' (10 -3 ) exp (1 .03 pH) (n = 61, r 2 - = . 0 .44)• (20 ) K=4 .97+0 .41'COND . (n = 61, r 2 = 0 .49) ALK = 0 .84 + 1 .1 ..38-K (21 ) There was a greater variation in potassium concentrations compared to th e other metals . There were also greater temporal and spatial potassiu m variations in those lakes so sampled . The reason for this variability is no t known . Summary of Metal Results : The regression between sea-spray-corrected total cation' concentration and alkalinity was given in equation (6) as follows : ALK = -8 .66 + 1 .05 SCAT (6 ) This relationship indicates that the bicarbonate ion (approximately equal to alkalinity) is the major anion associated with the major cations . Potassium , sodium, calcium and magnesium bearing minerals must be supplying equivalen t amounts of alkalinity in dissolution reactions . The regressions of total cations with conductivity and pH are as follows : CAT = -14 .41 + 9 .00 COND CAT = (n =63, r 2 = 0 .96) 1 .11 (10 -4 ) exp (1 .93 pH) (n= 63, r 2 = 0 .86) 19 (22 ) (23 ) On an equivalent basis, the average calcium :sodium :magnesium : potassium ratio was 36 :31 :26 :7 for the 63 lakes sampled . For three acidifie d lakes in the Adirondack Mountains of New York State, Driscoll (1980) reporte d an average Ca :Na :Mg :K ratio of 59 :16 :18 :7 . The average total cation concentration for the 63 Oregon Cascade lakes sampled was 168 ueq/l . For th e three acidified lakes studied by Driscoll, the average total catio n concentration was 207 ueq/l . Hence, Oregon's Cascade lakes are somewhat mor e dilute but ionic strengths are of the same order of magnitude . Aluminum and hydrogen ion concentrations constitute approximately 18 an d 5%, respectively, of the total cations in the acidified Adirondack lake s studied by Driscoll . These parameters have a negligible effect on the tota l cation concentrations of the lakes sampled in this study . Sulfate : The average sulfate concentration for the 63 lakes was 0 .28 mg/I, with a high of 2 .17 mg/I and a low of 0 .03 mg/I . The standard deviation was 0 .2 8 mg/i . The regressions between sulfate and conductivity and pH are a s follows : SO4 = 4 .50 + 0 .079 COND (n = 59, r ? = 0 .01) (24 ) SO 4 = 0 .55 exp (0 .29 pH) (n = 59, r 2 = 0 .01) (25 ) For the Oregon Cascade lakes sampled in this study, sulfate averaged 3 . 5 percent of the average total ions while bicarbonate averaged approximatel y 82% . Driscoll (1980) reported an average sulfate concentration of 6 .2 mg/ I for three dilute acidified lakes in the Adirondack Mountains . In dilute acidified lakes, sulfate replacep bicarbonate as the major anion . Wright an d Gjessing (1976) report that aqueous sulfate generally comes fro m anthropogenic sources and sea spray . The extremely low sulfate concentrations in the 63 lakes studied by us indicates that anthropogeni c sources of sulfate upwind of the Oregon Cascades are not present or are no t influencing the lakes studied . Chloride : The average chloride concentration of the Oregon Cascade lakes sample d was 0 .83 mg/I, with a high of 4 .10 mg/I and a low of 0 .30 mg/I . The standar d deviation was 0 .62 mg/I . Both conductivity and pH are as follows (no t sea-salt corrected) : CI = 1 .57 + 2 .12 COND (n = 63, r 2 = 0 .34) (26 ) Cl = 3 .46 (10 -5 ) exp (4 .26 pH) (n = 63, r2 = 0 .21) (27) These poor correlations may indicate that sources of chloride from withi n the watershed are negligible, and chloride is generally the result o f deposition of either sea spray or anthropogenic emissions . Sea spray was reported as the dominant source of dissolved chloride by other investigator s (Kramer and Tessier, 1982 ; Wright and Gjessing, 1976 ; and Henricksen, 1980) . Chloride averaged 15% of the average total anions in the 63 lakes sampled . 20 Fluoride : Total fluoride analyses were performed on samples from the eight lake s that were temporally and spatially monitored and on an additional 12 lake s that were grabbed sampled . Thus, average fluoride concentrations based upo n this non-statistically selected subset may not be representative of th e entire 63 lake sample size . With due caution, then, the average tota l fluoride concentration was 11 .8 ug/l, with a high of 82 .3 ug/l and a low o f <1 ug/l . The spatial and temporal variations in fluoride were very minima l for the eight lakes from which multiple samples were collected . Aluminum : Aluminum analyses were performed'on•samples from the 8 lakes that wer e temporally and spatially monitored . The average aluminum concentration wa s 16 ug/l, the high was 56 ug/l and the low was less than 1 ug/l . The standar d deviation was 16 ug/l . Nearly all of the samples analyzed had aluminu m concentrations less than 25 ug/l . These concentrations are typical of thos e reported by Wright and GJessing (1976) and other non-acidified dilute lakes . Driscoll (1980) reported an average monomeric aluminum concentration of 33 2 ug/l for three acidified Adirondack lakes . The average pH of these lakes wa s 4 .96 . It is well known that aluminum concentrations become greatly elevate d as lake pH decreases . Total Organic Carbon : Total organic carbon analyses were performed on samples from six lakes i n this study . Total organic carbon was below the detection limit ( 0 .1 mg/I ) for four of these lakes . Si I ica : The average dissolved silica concentration for the 63 lakes sampled wa s 7 .03 mg/I as SiO2 , with a high of 26 .6 mg/I and a low of 0 .05 mg/l . Th e standard deviation was 7 .27 mg/I . Good linear correlations were foun d between silica and both conductivity and alkalinity ; an exponentia l correlation between silica and pH was also found . These regressions are a s follows : SiO = -2 .69 + 6 .85 COND (n = 62, r 2 = 0 .63) Si O2 = 1 .06 (1 0 -5 ) exp (2 .21 Si 02 = 8 .63 + 0 .64 ALK pH) (n = 62, r 2 = 0 .72) (n = 62, r 2 = 0 .95) 21 (28 ) (29 ) (30) Driscoll (1980) reported significant seasonal fluctuations in silica fo r three acidified lakes . He attributed low summer concentrations of silica t o uptake by diatoms and high winter concentrations to decomposition of silic a containing frustules of diatoms . He stated that although silica is generall y used as an Indicator of the extemt of chemical weathering, it should not b e used as such because of the biological interactions in silica cycling, Ther e did not appear to be any temporal fluctuations in silica for the three-ment h sampling period . It is possible that this sampling period . was too short to reveal such trends . Correlation of silica versus alkalinity was very similar to correlatio n of basic cations versus alkalinity for the 63 lakes sampled . Hence, it i s possible that weathering processes supplying silica to these lakes concomitantly supply alkalinity and basic cations . 22 DISCUSSION-OF RESULTS Regional . Temporal, and Spatial Trends in Water Chemistr y r There did not seem to be any overall trends between lake water, chemistr y and lake location or elevation . Temporal and spatial trends in wate r chemistry were remarkably minimal in the eight lakes monitored for suc h variations . Significant fluctuations in some water chemistry parameters, such " as alkalinity, existed in the three smallest lakes that were temporall y monitored, but these fluctuations did not exhibit any overall trends . I n acidified lakes with short residence times, springtime alkalinities ar e generally depressed due to the slug input of acidified snowmelt ; alkalinitie s then increase throughout the summer (Driscoll et al ., 1980) . Fluctuations i n water chemistry with time were insignificant in the remaining five lakes tha t were monitored temporally . These five lakes had water residence times muc h greater than the three-month sampling period . A longer monitoring period , more commensurate with water residence times, might reveal such natura l temporal trends, if they exist . it is doubtful that there . are' significan t fluctuations in•seasonal water chemistry for Waldo Lake, which has an averag e residence time of 30 years (Davis and Larson 1976) . Larson and Donaldso n (1970) previously reported a lack of spatial variability in water chemistr y for Waldo Lake . Lost Lake showed a decrease in alkalinity with depth, bu t pH, cation and conductivity variations with depth were not significant . Zimmerman and Harvey (1978-79) reported the importance of collecting a composite water sample in contrast to a grab sample at the lake surface ; alkalinities decreased substantially with depth in the Ontario lakes the y studied . The large lakes investigated in this study had no alkalinit y gradient (except Lost Lake, as discussed above) and the small lakes wer e generally shallow enough to stratify only weakly, if at all . Thus, a surface grab sample was generally representative of the lake water chemistr y as a whole for the lakes sampled in this study . Predominant Buffer Systems : The carbonate system, organic aluminum, and weak organic acids all hav e been reported as significant buffer systems in lakes of igneous geologi c origin (Driscoll, 1980) . The carbonate system is the dominant buffer at p H values above about 5 .5 . Aluminum hydrolysis species and weak organic acid s become dominant buffer systems below this pH (Driscoll, 1980) . For the 63 lakes sampled in this study, the mean in-situ and lab, p H values were 6 .93 and 6 .96, respective)-y . These mean pH values, as. well as the pH range of 5 .83 to 7 .91 for the 63 lakes, are well within the range o f carbonate-dominated buffering . The average carbon dioxide partial pressure , as calculated from laboratory equilibrated pH and alkalinity (Stumm an d Morgan, 1981), was 437x10 atmospheres . The global average atmospheri c carbon dioxide partial pressure is 330x10 -6 atmospheres at sea level . Thus , the laboratory-equilibrated pH water samples were either supersaturated (b y an average of 35 percent over equilibrium carbon dioxide) or additional wea k 23 acid buffering was present . The extremely low aluminum and total organi c carbon concentrations indicate the very minor contribution of aluminu m hydrolysis species and weak organic acids to the overall acid neutralizin g capacity of these lakes . Logan et al ., (1982) also reported carbon dioxid e partial pressures in excess of atmospheric carbon dioxide for 31 lakes of th e central Washington Cascades . They attribute this supersaturation t o temperature differences between the lake sampled and the laboratory, wher e pH's were determined . In this study, pH was found to stabiliz e asymptotically over long periods of time (generally 1 to 2 hours) . This ma y indicate the existence of a kinetic limitation on the equilibration of th e water sample with atmospheric carbon dioxide in the laboratory . Such a limitation may explain the supersaturated carbon doxide partial pressure s calculated from laboratory-equilibrated pH and alkalinity . Figure 6 shows typical titration curves for several lakes with varyin g alkalinities sampled in this study . A theoretical titration curve for a system buffered only by carbonates (and water) with an alkalinity of 10 0 ueq/l and an initial pH of 7 .00 is also shown . The lakes with alkalinities greater than approximately 40 ueq/I have titration curves similar to th e theoretical curve . Specifically, there are smaller rates of pH change (fro m acid addition) near both the pKa value for the carbonate system and at low p H values, where buffering due to water dissociation becomes significant . Thus , the shape of these titration curves would seem to further indicate that th e carbonate buffering system predominates in lakes with alkalinities greate r than 40 ueq/l . The titration curves for lakes with alkalinites less than 4 0 ueq/l do not conclusively indicate the presence of any buffer systems (excep t water) to significant concentrations . A logarithmic buffer intensity curv e did, however, indicate that some buffering beyond that due to water wa s present at higher pH's even in the most dilute lakes . Therefore, Cascad e lakes with alkalinities greater than 40 ueq/l seemed to be predominantl y buffered by carbonates . The pedominant buffer system in lakes wit h alkalinities lower than 40 ueq/l was difficult to identify . However, th e neutral pH of these lakes and the low concentrations of both aluminum an d total organic carbon, collectively, seem to indicate that carbonates were th e dominant buffer system at very low concentrations . General Acidification Sens .itjvity Criteri a Many approaches- have . been presented in the literature in assessing th e sensitivity of water bodies to acidic inputs . When these models are applie d to Oregon's Cascade lakes, they generally indicate that these lakes ar e extremely sensitive to acidic inputs but have not been influenced by suc h inputs . The basic ionic strength and composition of a water body give a roug h indication of Its sensitivity to acidic inputs (Driscoll, 1980) . For th e lakes sampled in this study, alkalinity is significantly correlated wit h total cation concentration, as seen in equation 20 of Table 2 . 24 250 n 1 # LAKE (ALKALINITY> 1 LUCKY (3. 0) 2 SUMMIT C12- 0 ) 3 WALDO (17 . 1 ) 4 BETTY C33 . 0> 5 BRE I TENBUSH (46 . 3 ) 6 MOW I CH (69 . 9 > 7 LOST (83. 9) 8 BULL RUN (124 . 5> 9 T000(169 ..5 ) 10 THEORETICAL (100) (CARBONATE SYSTEM ) 20 150 0 H U s 100 1e 0 50 4 .5 5.5 6 6.5 7 PH Figure .' Titration Curves for 'TSelected .Cascade Lakes of Differing Alkalinity . 25 Most dilute, poorly buffered non-acidified lakes are dominated b y bicarbonates and Ca, Mg, K and Na as the major cations (Wright and Gjessing , 1976) . In acidified lakes, sulfate replaces bicarbonate as the dominan t anion and aluminum becomes a significant percentage of the total cations . The extremely low aluminium and sulfate concentrations in Oregon's Cascad e lakes (see Table 1), as well as the overall ionic composition, indicate that these lakes are typical of other dilute, poorly buffered, non-acidifie d lakes . According to Hendrey et al ., (1980), lakes with alkalinities less tha n 200 ueq/l are highly sensitive to acidification while only those lakes wit h alkalinities greater than 500 ueq/I are considered to be non-sensitive . Thus, 46 (73%) of the 63 Oregon lakes sampled would be considered as highl y sensitive, and only one lake would be classified as non-sensitive . The Ontario Ministry of the Environment (1981) proposes that lakes wit h alkalinities less than 40 ueq/l possess extreme sensitivity and those wit h alkalinities ranging from 40 to 200 ueq/l have moderate sensitivity . Twenty-one (33%) of the lakes sampled in this study had alkalinities les s than 40 ueq/l, 25 lakes (40%) had alkalinities of 40 to 200 ueq/l . Finally, Zimmerman and Harvey (1978-79) propose that sensitive lakes hav e pH values of 6 .3-6 .7, conductivities less than 30-40 umhos/cm an d alkalinities less than 300 ueq/l . Twenty-one (33%) of the 63 Oregon lake s had pH values less than 6 .7, 59 lakes (94%) had conductivities less than 4 0 umhos/cm and 55 lakes (87%) had alkalinities less than 300 ueq/l . Hence, b y these proposed criteria, nearly all the lakes samples are sensitive to acidi c inputs . Applicability of Acidification Sensitivity Model s Kramer and Tessier (1982) present a theoretically-derived relationshi p between total major cation concentrations (sum of calcium, magnesium , potassium and sodium) and alkalinity, using charge_balance considerations . This relationship, also proposed by Burns et al . (1981), as an indicator o f anthropogenic acidification is as follows : (31 ) ALK '= EMi - SO4 Where LMi = sum of major cation concentrations on an equivalent basis an d adjusted for contribution of sea spray (as described by Wright and Gjessing , 1976) . In geographical areas where carbonic acid weathering predominates , alkalinity and cations are released on an equivalent basis in minera l dissolution reactions ; hence, the slope of Equation 31 would be close t o unity (Kramer and Tessier, 1982) . 26 If strong mineral acid weathering was occurring in a particular area, the . slope of Equation 31 would be significantly less than unity ., indicating th e release of cations, but without accompanying alkalinity. (Burns et al ., 1981) . Burns showed that in areas affected by-acid precipitation,' t,i he alkalinity : total cation ratios were much- less than unity (indicating m+i . sera I aci d weathering) and ratios in unaffected areas were close to unity (indicatin g carbonic acid weathering) . For this study, the following relationship wa s obtained for regression of alkalinity as a function of total major cation s (sea-spray corrected) : ALK = 1 .05 Mi - 8 .7 r- = 0 .99 (32 ) See Also (6 ) The closeness of the slope to unity strongly indicates that carbonic aci d weathering dominates in the Oregon Cascades and that anthropogeni c acidification of the lakes has not occurred to date . In the derivation of Equation 31, Kramer and Tessier assume that nitrat e has a negligible influence on the overall aqueous charge balance . If nitrat e was present in significant concentrations, the intercept of Equation 31 woul d be more negative than if only sulfate was present . Hence, although assume d nitrate to be negligible in their derivation, Equation 31 is still useful i n areas that receive nitrogen-oxide-emission-induced acid precipitation . Thus , the sulfate concentration in Equation 31 can be substituted by the sum o f sulfate and nitrate (on an equivalent basis and sea salt corrected) . Although nitrate analyses were not performed in this study, the closenes s of the intercept term (7 .4) of Equation 32 to the average sulfat e concentration (5 .8 ueq/l) indicates that nitrate concentrations ar e negligible . Hence, it is doubtful that significant nitrogen-oxide-derive d acid precipitation is occurring in western Oregon . Empirical Relationships : Several investigators have used alkalinity-calcium relationships (and/o r alkalinity-calcium plus magnesium relationships) to assess the extent o f acidification in a particular area (Almer et al, 1978 ; Logan et al ., 1.982 ; Dr.i.scoll, 1980 ; Henricksen, 1979) . These models are essentially simplifie d and empirical approaches that can be derived from Kramer and Tessier' s theoretical charge-balance model . Kramer and Tessier similarly simplifie d their theoretical charge-balance model as follows : ALK = b (Mg ALK = b i +2 + Ca +2 ) - SO4 (33 ) Ca +2 - SO4(34 2 ) where b (of b ' ) must be greater than unity to account for the contribution o f sodium and potassium to the overall charge balance . This model, as well a s the similar models proposed by Almer, Logan, Driscoll and Henricksen, assume s that a relatively constant and linear relationship exists between alkalinit y and calcium (or calcium plus magnesium) for unacidifled lakes, and fo r acidified lakes previous to acidification . Kramer and Tessier (1982) mentio n the difficulty in using the simplified relations (Equations 33 and 34) due t o the variability in b and b° because of varying contributions of sodium- an d 27 potasium-releasing mineral dissolution reactions, even in a particula r region, to the overall charge balance . For this study, from Table 2 (Equations 9 and 13), b = 1 .49 (r2 = 0 .95 ) and b ' = 2 .42 (r 2 = 0 .87) . The alkalinity/calcium relationships for severa l other regions of the world with dilute, poorly-buffered, non-acidified lake s and one region with acidified lakes are summarized in Table 3 . Th e comparatively greater alkalinity/calcium slope for Oregon's Cascade lake s seems to indicate that significant amounts of sodium- and potassium associated alkalinity are present in addition to that supplied by calcium an d magnesium mineral dissolution reactions . Thus, Oregon lakes could incu r significant acidic inputs and substantial loss of alkalinity before thei r alkalinity/calcium ratio even approaches typical alkalinity/calcium ratio s for dilute non-acidified lakes in other areas, as indicated in Table 3 . Hence, the use of alkalinity/calcium ratios for inferring the extent o f acidification in impacted areas could lead to misleading conclusions . Kramer and Tessier (1982) mention (with caution) that the intercepts o f Equations 33 and 34 can also be used to indicate sulfate concentration in a way similar to the more rigorous Equation 31 . The charge balance-derive d relation (Equation 31) can be more reliably used for this purpose, but al l the parameters required to use it are not always available . If thi s hypothesis is applied to the alkalinity/calcium relation shown in Table 3, i t can be seen that su_Ifate concentrations are minimal in the lakes of thi s study as well as those in northern Norway, Washington and Ontario . Th e intercept of the alkalinity/calcium regression for the acidified lakes in Ne w York's Adirondack Mountains is, however, much more negative, indicating bot h the higher concentrations of sulfate in these lakes and probabl y anthropogenic influences on their water chemistry . Ca-pH Plots : Henricksen (1979) suggests the use of calcium-pH plots to distinquis h between non-acidified lakes and lakes that have lost some alkalinity (wit h accompanying moderate depression in pH) but have not lost all carbonat e buffering . Boundaries between acidified and non-acidified lake Ca-p H relations were empirically drawn by Henricksen based on data for acidifie d lakes in southern Norway and dilute non-acidified lakes of northern Norway . Figure 7 presents Ca-pH plots for the 63 Cascades Lakes, with Henricksen' s boundaries superimposed . It is evident that the data for the 63 Orego n Cascade lakes are all in the non-acidified zone and that they appear to hav e substantially higher pH values than the dilute, non-acidified lakes of bot h the Washington Cascades and northern Norway . Hence, Oregon's lakes coul d experience a moderate drop in pH (and some alkalinity loss), but still appea r to be umirpacted with respect to Henricksen's plot . Thus, again there seem s to be substantial contribution to alkalinity by weathering of sodium an d potassium minerals, resulting in high pH values in lakes with calciu m concentrations similar to those non-acidified lakes used by Henricksen in hi s Ca-pH plot . Zimmerman (1982) also indicates that lakes high i n magnesium-associated alkalinity may make Ca-pH plots inappropriate o r 28 Table 3 . Alkalinity-Calcium Relationships for Lakes From Various Region s Region Correlatio n Coefficient, , r2 Equation ]. Sourc e Oregon Cascades 2 ALK = -3 .70 + 2 .40 Ca 0 .88 This Study Central Washingto n Cascades ALK = - 5 .77 + 1 .07 Ca 0 .96 Logan et at ., 198 2 North Cascade s (Washington) ALK = 0 .98 Logan et al ., 198 2 Northern Norway ALK = -29 .0 + 1 .32 Ca 0 .85 Henrtckseny 197 9 Expt'al Lakes , Western Ontari o area ALK = -32 .0 + 1 .42 Ca 0 .76 Henricksen, 197 9 ALK = -94 .9 : 4. Adirondack Lakes , New York . 2 .67 + .995 Ca 0 .94 Ca Driscoll, 1980 'Units for ALK and Ca are ueq/ l 2 Regression of non-sea-spray corrected concentrations (for comparativ e purposes) . 9 (1/ ban ) Wn 131V J 30 misleading as indicators of acid+fication . Hence, Ca-pH plots should b e interpreted carefully, since alkalinity-supplying weathering reactions ma y differ from one region to another . Kramer and Tessier (1982) suggest that plots of total catio n concentration vs . pH may be a better benchmark for comparing lakes o f different regions . The use Of such plots as a compenative benchmark seems t o have theoretical Justification, as alkalinity is related•to pH . However, th e difficulty in comparing pH data among investigators still exists (Driscoll , 1980) . Carbon dioxide partial pressures vary significantly due t o photosynthesis-respiration activity, wave action and temperature changes, al l resulting on pH fluctuations : These variations were minimized in this stud y by determining pH under consistent, laboratory-equilibrated conditions . Th e variability in pH data between different investigators has not, however, bee n resolved . The total cation concentration-pH regression for the 63 lakes o f this study is shown in Table 2, Equation 23 . Similar regressions for lake s of other regions are not readily available . Ca-pH plots, Ca-alkalinity plots, metals-alkalinity plots and metals-p H plots, when used to predict extent of acidification, aLl implicitly assum e that cation concentrations do not change as a water body is acidified .. According to Kramer and Tessier (1982), some investigators found no change i n calcium concentrations with acidification, while others found increases i n calcium and other cations . Increased cation concentrations woul d overestimate either pre-acidification alkalinity or loss of alkalinity fro m acidification, depending on how these relationships were used . Henrickse n (1979) hypothesizes that dissolution reactions which increase calcium an d that other cations would probably also supply an equivalent amount o f alkalinity . Typical mineral-acid dissolution reactions would not, however , release equivalent amounts of cations and alkalinity . Henricksen (1980) has developed a nomograph which can be used to predic t lake pH from lake calcium concentration and either precipitation pH or lak e sulfate concentrations . This nomograph has limited applicability to Oregon' s Cascade lakes, as lake sulfate concentrations were generally too low to us e the nomograph . At best, the nomograph indicates that Oregon's Cascades lake s have not received acidic inputs . 31 CONCLUSION S Briefly, the following conclusions may be drawn from this study of 6 3 Oregon Cascade lakes : 1. Oregon's Cascade lakes have an extremely dilute ionic compositio n relative to typical freshwater lakes ; 2. Most Oregon Cascade lakes are highly susceptible to aci d precipitation and could be adversely impacted if aci d precipitation were to increase ; 3. Based on chemical composition, Oregon's Cascade lakes sho w no signs that significant acidic inputs have occurred to date ; an d 4. Comparison of the data from this study to data for dilut e non-acidified lakes in other geographical areas indicate s that natural differences in water chemistry are significant . Conclusions regarding the extent of acidification based upo n comparison of fake data from one region to another must b e made carefully . Oregon lakes could incur significant acidi c inputs but appear to be unimpacted if certain empiricial an d comparative models in the literature are used . 33 REFERENCE S Almer, B ., W . Dickson, E . Ekstrom, E . Hornstrom ; "Sulfur in th e Environment, Part I I : Ecological Impacts" ; Nr i agu, J .O . Ed . ; J .O . Wiley and Sons, Inc . ; New York ; 1978 ; p . 271 . Barnes, R .B . ; "The Determ j.iitt i on of Specific Forms of A I um i raw i n Natural Water, "Chemical Geology'• ;'V_ . 1 .5 ; 1975 ; p . 177-191 . Burns, D .A ., J .N . Galloway and G .R . Heradrel ; Ac idifi.cation o f Surface Waters In Two Areas of'the Eastern United States , "Water, Air and Soil . Pelkution" ; V . 16 ; 1981 ; p . 277-285 . Davis, G .E . and G ..L . Larson ; "Sediment Characteristics and th e Trophic Status of Four Oregon Lakes" ; Water Resources Researc h Institute, Oregon State University, Corvallis, Oregon ; Repor t WRRI-46 ; 1976 . Dillon, D .T ., D .S . Jeffries, W .A . Schreider and N .D . Yam ; "Some Aspects of Acidification in Southern Ontario" in Proc . Int . Conf . on Eeol . Impact of Acid Precip . ; Drablos, D . and A . Tollan, Eds . ; Norway (SNSF Project) ; 1980 ; p . 212-213 . Driscoll, C .T . ; "Chemical Characterization of Some Dilute Acidifie d Lakes and Streams in the Adirondack Region of New York State" ; Ph .D . Thesis, Cornell University, Ithaca, N .Y .. ; 1980 . Driscoll, C .T ., J .P . Balcer, J .J . Biscogni and C .L . Schofield ; "Effec t of Aluminum Speciation on Fish in Dilute Acidified Waters" ; Nature ; V . 284 ; 1980 ; p . 161 . Gran, G . ; "Determination of the Equivalence Point in Potentiometri c Titrations, Part II" . Analyst ; No . 77 ; 1952 ; p . 661-671 . Haines T . ; Comments, Trans . of American Fisheries Society, Ill ; 1982 ; p . 779-786 . Heradrey, G ., J .N . Galloway,. S .A . Norton, C .L . Schofield, D .W . Schaffer , and D .A . Burns ; "Geological and Hydrochemical Sensitivity o f Eastern United States to Acid Precipitation'" ; EPA Ecologica l Research Series, EPA 600/3-80-024 ; Corvallis Eavirommental , Research Laboratory, Corvallis ; Oregon ; 1980 . Henricksen, A . ; "A Simple Approach for Identifying and Measurin g Acidification of Freshwater" ; Nature ; V . 278 ; April ; 1979 ; p . 542-545 . Henricksen, A . ; "Acidification of Freshwaters--A Large Scale Titration " in Proc . Int . Conf . on Ecol. . Impact of Acid Precip . ; Drablos, D . an d A . Tollan, Eds . ; Norway (SNSF Project) ; 1980 ; p . 68-74 . 35 Jeffries D . and A . Zimmerman ; "Comments on the Analysis and Sampling o f Low Conductivity Natural Waters for Alkalinity" ; Can . J . Fisherie s and Aquatic Sciences ; V . 37 ; 1980 ; p . 901-902 . Kramer, J . and A . Tessier ; "Acidification of Aquatic Systems : A Critique of Chemical Approaches" ; Environ . Sci . Technol . ; V . 16, No . 11 ; 1982 ; p . 606A-615A . Larson, D .W . and J .R . Donaldson ; "Waldo Lake, Oregon : An Ul.tra-Oligitrophi c Environment and Some Implications Concerning Recreational Development" ; Water Resources Research Institute, Oregon State University, Corvallis , Oregon ; Report WRRI-2 ; 1970 ; 21 p . Liljestrand, H .M ., and J .J . Morgan ; "Chemical Composition of Aci d Precipitation in Pasadena, California" ; Environ . Sci . Technol . ; V . 12 ; 1978 ; pp . 1271-1273 . Logan R .M ., J .D . Derby and L .C . Duncan ; ""Acid Precipitation and Lak e Susceptibility in the, Central Washington Cascades" ; Environ . Sci . Technol . ; V . 16 ; 1982 ; pp . 771-775 . Oceanography International Carbon Analyzer Instruction Manual ; Oceanography International Corp ., College Station, Texas ; 1974 . Ontario Ministry of the Environment ; Acid Precipitation in Ontario Study ; APi 002/81 ; Toronto, Canada ; 1981 . Orion Moael 601 A Digital Ion Analyzer Instruction Manual ; Orion Researc h Inc ., Cambridge, Massachusetts ; 1977A . Orion Instruction Manual, Flouride Electrodes ; Orion Research, inc . , Cambridge, Massachusetts ; 1977B . Orion Moael 211 Digital pH Meter Instruction Manual ; Orion Research, Inc . , Cambridge, Massachusetts ; 1981 . Perkin-Elmer Analytical Methods for Atomic Absorption Spectropbtometry ; Perkin-Elmer Corp ., Norwalk, Conn . ; 1973 . Powers, C .F . and D .L . Rambo ; "The Occurrence of Ac,i,d Precipitatio n on the West Coast of the United States" ; Environ . Monit . Assess . ; V . 1 ; 1981 ; p . 93 . Schofield, C .L . ; '!Effects on Fish" ; Ambio ; V . 5 ; 1976 ; p . 5 . Shulters, M .V .,•• "Lakes of Oresgon . Vol . 3 : Hoed River, Multn,omah., Wash i .ngton, and Yamh i I I, Counties ; Vol : 4 : Clackamas County ; an d Vol . 5 :' Marion County" ; U .S . Geological Survey, Open File Reports ; 1975 and 1976 . Snoeyink V .L . and D . Jenkins ; "Water Chemistry" ; J .O . Wiley and Sons , New York ; 1980 . 36 Standard Methods ; 15th Edition ; Standard Methods for the Examinatio n of Water and Wastewater ; American Public Health Association , Washington, D .C . ; 1980 . Stumm W . and J .J . Morgan ; "Aquatic Chemistry" ; 2nd Edition ; 4 .0 . Wiley and Sons, New York ; 1981 . U .S . Environmental Protection Agency ; "Methods for Chemical Analysi s of Water and Wastes ; National Environmental Research Center , Cincinnati, and Office of Technology Transfer, Washington, D .C . ; 1974 . U .S . Geological Survey ; Water Resource Data for Oregon ; 1981 . Wright R .F . and E .T . GJessing ; "Changes in the Chemical Compositio n of Lakes" ; Ambio ; V . 5 ; 1976 ; p . 219-223 . Wright R .F . and A . Henricksen ; "Chemistry of Small Norwegian Lakes , With Special Reference to Acid Precipitation" ; Limn®logy an d Oceanography ; V . 23 ; No . 3 ; 1978 ; p . 487-498 . Zimmerman, A .P . and H .H . Harvey ; "Final Report on Sensitivity t o Acidification of Waters of Ontario and Neighboring States" ; Ontario Hydro, Univ . of Toronto ; 1978-79 . Zimmerman, A .P . ; "Sensitivity to Acidification . of Waters of Ontari o and Neighboring States Ii : An Analysis of Data Set Variance an d Prediction of Acid Sensitive Lake Areas" ; Ontario Hydro, Univ . o f Toronto ; 1982 . 1 3T. . APPENDICES' •i . I . ' II I A. LIMNOLOGICAL DATA FOR SEVEN CASCADE LAKES B. CHEMICAL DATA FOR 63 CASCADE LAKE S C. DISCUSSION OF EXPERIMENTATION IN LABORATORY TECHNIQUE S 39 - Appendix A . Limnological Data for Seven Cascade Lakes . a DULL RUN LAKE DEPTH (feet) 0 10 20 25 30 35 40 44 45 50 60 70 80 90 100 TRANSM . TEMP . D .O . (percent) (C .) {mg/L) --------------------------- ND 19 . 0 7 .90 ND 19 . 0 7 .6 0 ND 16 . 0 8 .6 0 ND ND ND ND 10 . 0 10 .0 0 ND ND ND ND 5. 5 9 .7 0 ND 5. 2 9 .0 0 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ---------------------------(7/26182)-8 F .M . `CALM, SUNSET TRAMSM . TEMP . D .O . (percent) (C .) (agIL ) ---------------------------100 18 .7 7 .7 5 60 18 .7 7 .6 0 45 17 .5 7 .4 0 ND 15 .4 8 .8 0 38 14 .0 9 .9 0 ND 9 .8 10,2 0 29 8 .7 10 .4 0 ND ND ND ND ND ND 28 6 .6 10 .40 ND 22 ND 22 ND ND 19 ND ND 16 ND ND 12 ND ND --------------------------- (8/27/82)-4 P .M . SUNN Y r TRANSM . TEMP . D .O . (percent) (C.) (ag/L ) --------------------------- ND 11 .1 9 .1 0 ND 11 .1 8 .95 ND 11 .0 8 .85 ND ND ND ND 11 .0 8 .85 ND ND ND ND 10 .6 8 .90 ND ND ND ND 9 .3 9 .0 0 ND 6 .5 10 .2 0 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ---------------------- i w (104t82)P .M . ." CHDPRY ►- ~ , a N LOST LAKE DEPTH (feet) 0 10 20 22 25 28 30 35 40 45 50 60 70 80 90 100 TRANSM . TEMP . D .O . (percent) (C .) *IL) --------------------- 100 19 .5 7 .30 65 19 .1 7 .40 42 16 .3 7 .90 ND ND ND ND 12 .2 9 .30 ND ND ND 31 9 .8 9.40 ND NO ND 24 7 .2 9 .80 ND ND ND 20 6 .0 9 .50 16 ND ND 13 ND ND 9 ND ND 65 ND ND 4 ND ND ---------------------------(7127/82)-11 A .M . SUNNY,CHOPPY TRANSM . TEMP . 0 .0 . (percent) (C .) 4g/L ) --------------------------- 100 19 .0 7 .3 0 65 18 .9 7 .35 43 18 .7 7 .3 0 ND 18 .0 7 .60 ND 16 .5 8 .3 0 ND 13 .9 9 .50 32 12 .2 9 .70 ND 10 .0 10 .00 25 7 .8 9 .80 ND ND ND 20 6 .3 9 .80 16 ND ND 13 ND ND 9 ND ND 6 ND ND 4 ND ND (8128/82)-12 A .M . SUNNY -TRANSM. (percent) TEMP . (C .) DA . (ag/L ) --------------------------- - 100 11 .5 9 .1 0 60 10 .4 8 .9 0 45 10 .3 8 .9 0 ND ND ND ND ND ND ND ND ND 38 10 .2 8 .80 ND ND ND 32 10 .6 8 .60 ND 8 .0 9.90 26 6 .5 10 .00 19 ND ND 14 ND ND 9 ND ND 5 ND ND 2 ND ND ---------------------------{10/15/82)-9 :30 A.M . SUNNY, CALM Appendix A . Continued . WALDO LAKE (SOUTH END) DEPT H TRAM . (feet) (percent) TEMP . D .O. (C .) teg/L) (percent) TRANSM . TEMP . D .O . TRANSM . (C .) (ag/L), (percent) TEMP . (C .) (ag/Li D .O . 7 .90 0 100 15 .8 7 .70 100 16 .9 8 .10 100 13 .2 10 63 15 .1 7 .50 74 16 .8 7 .8'0 74 13.0 7 .85 20 55 12 .5 7 .90 64 16 .4 7 .90 69 12 .9 7 .50 25 ND 11 .7 14..2 ND ND ND ND ND ND ND ND ND 28 ND 13 .1 ND ND ND ND 7 .6 5 30 48 9 .9 8 .65 56 11 .5 9 .45 61 12 .9 35 ND 7 .8 ND ND 10 .1 ND ND ND ND 40 ND 7 .0 8 .75 48 9 .4 9 .65 56 1'2 .8 7 .7 0 45 ND ND 50 36 6 .1 60 70 33 80 ND ND 8 .5 ND ND 11 .4 5 .2 2 8 .80 44 8 .0 9 .80 53 10 .3 _8:85' ND 38 ND 38 ND 48 44 ND ND ND ND ND 30 ND ND ND ND 28 ND 38 ND ND 41 ND 38 ND ND 39 38 7 .5 ND 36 ND ND ND ND 90 26 ND { ND ND 100 24 ND ND . ND ------------- - (7/12/82)-6 P .M . (8/x/82)-11 A .M . SUNNY,`CHOPPY (97 =17/821-3 P .M . SUNNY,CALM . SUNNY,s.CAL M WALDO LAKE (NORTH END ) DEPTH (feet) 0 TRANSM . TEMP . D .O . (percent) (C.) (ag/L) --------------------------- - TRANSM . (percent) TEMP . D .O . (C.) (ag/L) TRANSM . • TEMP . (percent } . _ (C. l , 0,0 . Gli/L$ ND 16 .5 7 .90 100 18 .2 7 .85 100 10 ND 15 .8 7 .90 85 17 .2 7 .65 79 12 .5 12.5 20 ND 14 .8 8 .20 67 16 .6 7 .73 67 12 .3 22 .ND ND ND ND 16 .2 7 .80 ND ND ND 25 ND ND ND ND 14 .0 9 .20 ND ND ND 28 30 ND ND ND ND 12 .1 9 .35 ND ND ND ND ND ND 46 11 .5 9 .47 59 12 .3 7 .80 ND 55 ND ND 12 .3 7 .3 0 ND ND ND 37 ND ND 10 .0 9 .45 - .ND ND ND ND 40 ND ND ND ND 45 50 ND 'ND ND ND ND ND ND ND ND --------------------------- - ND ND ND --------------------------- - (8/6/821-8 P .M . SUNSET, CALM 8 .1 0 7 .90 7 .80 48 12 .5 6 .2 0 ------------------------ - (9/17/82)-1 P .N . SUNNY, CHOPPY ,= 1. Y• Appendix A . Continued . C- : SUMMIT LAKE (WILL . PASS) DEPTH (feet) 0 10 15 20 25 30 40 50 TRANSM . 'TEMP . D .O . (percent) (C .) (egIL) ---------------------100 15 .0 8 .00 100 14 .8 8 .40 ND 3 .8 ND 98 • 13 .3 9 .00 ND ND X2 .5 B4 12 .4 9 .75 74 ti 12 .2 9•.80 61 11 .5 9 .95 ----------------------- (7/13/82)-11 :3d A .M'. OVERCAST 'CHOPPY TRANSM . (percent) TEMP . (C .) D .Q . (ogIL ) -TRANSM . TEMP . D.O . (percent) (C .) (0g/L ) ------------------------100 13 .5 7 .90 80 13 .5 •7 :6.0. 67 .ND AN D ND 7 :1 0 ' ND ND ND- r 61 13 .5 ` 7 .65 - . •7 .cn . :10 1.3 .5 48 13 .5 6 .84 - 'F ND 19 .0 7 .7 0 ND 18 .6 7 .6 0 ND ND 'N D NB' 18 .4 7 .4 0 ND ND , ND ND 1B :2 . 7 .50 ND 18 .1 . - L.3 - ` ND ND '(D -------------------------(8/7/82)-4 :30 P .M . T-STORM,CALM (9/18/82)-9 :30 A .M . PART .SUFNVY,CAL M OLALLIE LAK E { DEPT H {feet) TRANSM . (percent) TEMP . IC .) D .O . (sg/L) 0 10 20 25 30 38 40 50 100 60 52 ND 43 ND 36 ND 18.8 18 .5 17 .9 . 16 .8 13 .6 12 .0 ND 'ND 7 .50 7 .25 7 .10 7 .40 8 .85 8 .50 ND ND TRANSM . TEMP . D.O . (percent) (C .) (®g/L) ------- ------- ---------ND 18 .0 8,00 MD` 18 .0 7 .90 ND 18 .0 7 .95 ND ND ND 18 .0 7 .90 ND ND ND ND ND 18 .0 . 7 .80 ND ND ND - TRANSM . (percent) . TEMP•-- -NO . (C .) ( .g/L ) ND . 9;0 &/45 ' . ND 8 .9 8.41 0 ND 8.9 7 .95 ND ND ND 119 8. 0 .NB 4D ND - ND 8 .8 7 Nb :, ND ---------------------- - (7/28/821 ;4 P .M . SUNNY,'GHOPP Y (8/29/82)-11 A .M . OVERCAST ,CHOPPY (10/15/82)-3 :30' .M•.. PART .OVEICAST,CHOPPY 1 Appendix A.} Continued . BLUE bME - DEPTH (feet) 0 2 4.' 6 8 10 15 20 . 30 '<, • 40 , , 50' 60 70 80 .90 100 - TRAM . (percent) TEMP . (C . ) 100 ND ND -ND ' ND 62 ND 51 41 37' 33 30 29 25 23 21 14 .0 14 .0 14 .0 13 .8 10 .5 9 .0 7 .5 7 .0 6 .2 5 .8 5 .2 ND ND ND ND ND ,. DOT , 9 .4 5 9 .50 ' I - . :9 .50 ' 9 .60 11 .8 0 12 .30 12 .5 0 12 .70 12 .50 12 .40 12 .20 ND ND -ND ND "ND ELK LAKE DEPTH (feet ) TRiN I . (percent) TEMP . 0 100 25 41 35 31 ND 16 .8 1648 . 16 .8: 16 .4E 14 .5 10 15 20 (C .) . D.O. • (sq/L ) 7 .6Q J.4 • 7 .-b S 8 .50 ° x a ° x ° a bz x z z 2 Z 2 Z Z r x M = v 10., i ` O N O l1. d t d E q Z b Z Z 2 = Z A b Z b Z ° Z b Z b Z A Z Z Z b IN Z Q co 0` O 0+ ^ O• O M M 1If11'i f4Y A ry .0 V W O .0 N h N •-• Q In M M 4 P M H M M N M H M M N M y M H 0 2 ,-1 4 ^ • ClM MM P 4 M h M Cl M M N l Cl Cl M M M I1 Ih M M M M M M C co O O m 9 O- aO T 0100,030 4. A o- O^ M 4-• O O ^ O O O O O • .O O r p .4 '"'~ [T "" "+ r •'~ -0 0• .0 M O W O P M M O • 47 O N N. ^ 0 p W 4l N N Cl P ^N 11M 0000 Mi r YW U W J A M m 4 O O .0 h m 4 9 M N M 00 O 0 M N 0 T N A ° ° Ci q ° V9 O ° x p Z Z Z Z 2 `? .. 000 I1' y M MM O 4 p O O O O 10 N ® O M O O O O O N O 001 0 V' 0 a 4 sl- ^ ..1117 M R N W J A J G 1--1 5. _ Is. 0• N ^ 4 M 0. 0 M O A N Y Z 4 Z W Q J N 000 4 ▪ N a O OpO O O O O In 4 1!'1 000000 4 117 4 CO .0 h p O O O O O r ^ N O co 000010 r N Y'9 Cr. G M y .h.. N 4 . .• N O O 0 p 4 4 W .... O O 0 m W • ▪ y ▪ m ti .p y r CI O O O O In N o q M N A N h O .p y n a N ~ • m v • m m h Co M s N 4 M ▪ In .N' Cl 0` 4 O M ▪m • . 00 m0 N 4 O MA N O O p O Y'9 h • ti P - N N J M .0 m N + J U -.31' cr In M In o.O O O i t M O m 9 T N O O -0 W M ^ N N N V4' CO Y Y'9OA , 17 ▪o8. m I .i ▪ M 0- r1 -0 CO 014 v N M Cl N 2 C l U x C L1 N [T CIS. m o N co lrl In M M O N M N M M N N co Q J cO 4 C NO A A W a H m Y9 m .0 4-4 N0 p M h A A A P I-G.7 M M H M • O ▪ b .O •4 Y7O O IOC) If1 P CO O 0 19 0 Is 1°' • 4 D N . W - CI m N 117 ▪ N Cl CO M O 0 co • T. N R N m Y9 In CO M y P •4-0 .0 o In 1!9 Y7 n 11M'▪f cIH ▪ 0. 0, 0` q 4 C. m •0 = ▪ O a W N U H co N 0q 0 3 N C • O O No cr. N m va ▪ O OWN O 0 o A h a • H q O▪ .0 In O l C 11'9 N 49 O COn-0 A N N l C In .0 0` W In M W N NN • y N M M H 0 O - • M M M m 4 0 o I17 .0 Y'1 a N CO P 0. Cl- h c N In - N of in o Iri v7 .0 A q M O O 4 N N b ▪ M Y7 N 1107 .O .0 b A ` A w ~ A h r m W - m O- 0- ~^y r ... r y V aaa JIn Y -U S 6 ~ L Q 4 J = Y > W C • J IC Q j > J J J W ° Cr. C1 • m Il9 K 45 r• 1 QO U • O J JUU Z 10 01 11 }} r r N O ▪ O 11' 1 . .1- M W • O O iIl Mh M ^ M Z N O b M m 1107 -C ^ N O h O CO C P M In Y1 n .0 In b A ▪ O y 3 1~ V O 4 0 ▪ 4 0• a N N N P CO y7 ,- Y 8 co ▪i A b rt ▪ W 7 W M Mf1 Y. 0 0 IY1 A N O. 0• c-L 4 • M N N .m W▪ I.M7 00 1M 17 m q N M N MM ▪ N N O O O q q O O p O p p G .•0 h I1dj P CO sc. m In M m N N Y7 01 0 . . .0 h C' m W ° ~1 o, Y 3 C a GJ_f Z m CC • ▪ i 47 O m t I M m 6 Or, O H -4+ .4.• N N ^ 00 S p M Z ry N O O O O O p Gf O 6 O O O O O 09210 0 0 4 0 0 .0 e A 0, co 4-M h m D: 2 O O O O "'• O ^ O O O O Z O O ^ Or N 6 O IP 0. M O O O O O W VM` ..• N IC . N M m • A M N N m 07 N b 1~ =_ = 6 > U J Q Y p U J J J = W ! r ` z N W N 4 m 0 W -0 4f co M 11'9 L-co 47 • O ^ 4 r h F 4 T O^ CO M M O O O ° z P M 92100 O P O O 0 00=00010 M 2 N m A O• 2 r O .. . O O O• O OO P N ^ M ^ O h O T N b M P a CO b P CO U, O N 0' M O .p O Z M M M M M N N▪ Inn M NM N 1!1 m 4 N 4 CO ^0 N W N 11'Y M ~'1 P m A ~` W CO r .0 m y O• O M .-. N .. . N o.• .~-. ^ N Y'f N N N N P N y N ~. b 0000 _ ° P •r Gi Ln = ° Z `+ Z o Gl Z Z N x h .0 Z Z ,,,. N Z m O .0 In 6,0 m m 41 ^ A O ° W h9 W m Y7 In .0 m ry - P I~ o q O O O ^ q▪ p O O r LL Z Z ° i O M a z O Z b b ob z b z o z r r I % b a b Z ° ° b z Z Z x x Z a Z ab x Z a O v A M In 1'1 In P H M N N M In m O 0 0 000 N M H M M M M N M M M H - 10 M N n l -n O . V49 0-02 119 N C Cl N Cl m M Cl Cl M N co ICI N M M M M M M MM M M M M M M M LW W I I ¢- 2 OO 0 P a zacz2z0 r 0 x z 0 A z A a A z A a A 2 0 z A 2222 p 2O y O: z aA aA zA ax A x ° z U O J A O A A x A i A 2 O A O a 221112 2 p p22 A x Z 1222 Z p 2 22 x p x O x A z A x 2 x A 2 2 z A ~ Z O i A z A 2 x 2 A i A 2 ▪ Prt1!9 b CO lf9 m M O t e M N In H M M M M M M H H M H H so- M V b 2034 e M M M MHM M M FW EC..., P LL co O 2 U J \U yLF W 2 2 O Up •. ! I ! O O O O 2. i 2 Co CO M CNO 6 p O M J Z _ ` H w ONO H N N .ti M N N M M M M H ~ O CO O ~ r P O ~ PP P CO. O O O O O 9 r -0 b Y'9 r -0 P. -O O v N ..• In CO h r N 4^1 v O! M M M N M ~ O y~y^y O O O P q Prp.O o = 1273 N O. 1 O O o OO N M O O P P P Z A x = O 47a-• r ui aLPy Om b h r-a N Y M b O 11 b H H W N h 19 N ^• N N -0 m M A x O V -0 CO O N P N P CO 11'1 W s ▪ U p L-0 v r M M O Ifl v M Co - O N 1~+ r M . v ryF r. M II'9 N MM ^ r M W N A to _ ` P ^. • Z A 2 2 0• 2 2 q p Z A 2 p 2 b N 0 2 2A O 2 A 2 A 2 2A2A A 2 O 2 0 2 NV 4. O~ 6 1! N-. N ^ N N H -0 Y CoO N ti' L19 d' 1.1 ® 4 V9 N r b b M 4~. CO r M N LeyO b -0 I!9 IL'9 M H N . fr M M M H Nl N M M M M M H N M N ; N O H M 2 N M 01 .M.. h b N O e M M M M M M M M M M M M M M M M M M M M M 222222Z2222 2 2 22222222 2 OOO O O O O O O OOO O O •O O O O O 2 2 a 11-9 2 2 2 S 2 2 11'9 2 2 2 4'9 2 II2 Or 2 C. e. -0 O O O O O O O O O O o O O O O O O O r P m ^ Y ~. O. . O O .O ~• •F N O bO' .0 . O O O V. m OO P .O .-. N y ^• ... ti •-. ~• If9 l1'9 co co M -~ O• N h rII'.9 Y9n' N y r A A O A 2 2 2 2 2 z 1 V.,1 2 A2 <-a -0 b P b r N_. 4'! Q m 2202222 2 O O• O O O O O O O• O M O .O Q T O 2 A - 0 ..• N ~ . O •-+ O O p N 4'L Co O . O• H O. N .rr N f M .N-•r O CO43- 3-3'9 O O b m N m n Itp'9 I- 4OM 3, h P n 11li 4o Lf9 O 3-3 -o N ® O N N It9 ... M O N L..~ N ^. ~. ~• + o O N O O M -N.'. O O ~' .+ ^ NN ti + N « Y CO If9 O P O - cc 0 P < r M In N r r 0 0- P M C M N -.0 r C/ OMOp N I."1 1N •S r M O] M O O O O ..• O O O O N . ..~ O O O O O O O O O .ti d O O O -. N •"• O Cr .ti = Cfl W 0 O m 2 L11 2 W O j.W ¢ 2 o W.[AA 2 2 2 QW 6O l92 co 2 OJ P- . •4 h N -0. . O O O O O q CO Y LO Z Q ? Q O 2 Z i Y2 Q AW Z CO CO Q ¢ ¢ JO p FJ¢ 2 LO 6 Q Q 1--4 S ¢ ¢ 2 2 J = p 2 J 4 Z I44 V G H i i [!] 2 Y CO O O N M . M. M1 V' IIP..1. 2 .' @ O M▪ O] v. q O O O O O O O O O O 4 = Ln P = M N O '1 NM •"~ O O b . O Y7 '221 O CO N m m t Ny. O V' OO N 11'9 P II9 M N lA h ~. O] M y N -O rt N P lf9 n O y co M-. V N b O .t H -p .N. y O N .N- . M d O ^ .r. y O NM-. M OO 0 2 W J W W ¢ = J U 1-- 3 6 Y S W J C 0222223 23 W J W 2 O 2 2 2 2 ¢ WC La_ fTf9 i 6 W OC h G J Mm 1!9 M .. < P r -0 V. 11-!-0 CO P M O O O O O O O O O O O O CO 4'9 M r O -V0J M 4 V m N n M .r-. -bO .p •m¢ Si 4M9 N OMO .2. Y -MO P M 1.0"L O .H-. I.WP CO -4 CO N M y P O -M 119srN +I. ON N y r M Y r ^ M p ~ . ~. N .r-. M MN P N N MM 119 O M tsar N + \ 4 A0. coM b MO b N-. ryN M N N iV r O 11'9 0 ^ .~. m -N .. O 0 P O M 0 r - N NM d' 0 NI r, O O OO N ^ z i o O o 0 0 0 0 0 0 .. . O o o q o 0 o 0 0 0 0 0 0 0 0 .. 0 0 0 0 N J m OO O O O. "" 11' lA -0 IP9 N CNO_M O ... R If.9 b N H N N M if9 11'CO9 t!'! 44. 117 N . r V. N .r.. F O 11"4 r LI '9 M r -0 . U O. ~ U Q 2 6 .~W p O IfUI N U La ¢ 6 V P O l!Hf I!9 ..: O W -0i M ~~ 1109 O~ or)' Ci R 4M'9 M.. M n N m .Y'f- 47 .b-. -co 11.9 Y n H O h M CO N r 0O .y N r b r r '• M 4 m co In CO < P N .-. 0 ^ N w N M N N b O ® co N qm-•P cob coN MOO l17ONs co M b N 11'l N If1 Ifl M CO N P b 11'] 3-3 r CO 11'9 .0.. P I .1 r O r MM NN •'bIPL m N V b N r M -0 4 rt N N C N M N b a d- W U M 4 + ^ PN Si IL-L co. -1N4 P N M N tV .! 11'I P CO = N O Ir9 N M N M M N b M 2149 - H-0 11'f N 3... P O O ^ v .-O. M P N r M.. P.~ O N M P rO N n 4'9 4 A . `a A r h 4 •a 1~ ri r 4 4 -a Ir, r h. . -O b r f~ r -a • h . 44 N T H n P H M H. O n m m N 4m'9 1!9r •-• CO @ ObN + M'! n N P 4 s O 1fl m m A 44 CO -0' b , r ,a .a -a , -a -0 -a d -0O m.O b. Ir, .a r M-o -a b r r b -0 u•; d '-'• O M O O O O O O O O O N q O O O O O O O O . N ••C- O b d ssP --O r h I.r" r b b 47 N V9 V7 -01 b mO b -0 10, ` co. b co P r -0 b -0 12 .22 r r r _ NO.N CO co co r A r CO r r r q. co co 41 -~ O O O O O O N ...~ b P O n P -0 r m -0 r b n b 2 MY '!"! b -0 -0 ` ` 22210, r r P P P p. Co r sr. CO - Q J W ••-• . CO-. 2 226 2 t99 OI V 0 Z 2 2 4 N W 2 O a 2 r W 2 O y 2 G z C O J y 6 U J LD 0 ¢ ¢ J 0 W O ¢ O_ H I-- 2 2 La 2 ¢ ¢ CC 2222E2 LLya 2 2W ca J O 0y¢ W2 2 2 2 2 U . p N a .i Y-.. S=W Ls. 4B Go -I 46 i ¢ 4 0 F, M N N N N O 0 9 7 M 2 2 M .h.. 2 N N G co M r'1 M M N M O M N •T V7 0 IM MM MY Mh M I.MYN N r, 47 O O. NI NI r7 NI rM M Ny M M Nf 0 ry M b Mh M MM Y h MMY N b M ^~ O -M7MM M oC. W .. w a m J k ? N 2= 0 a W h CI In U .OO p 0 . P 0 fn O> J 6= 3' b 1 a Q= W F- J U ` W3 Oa 0 0 CO m 11'a 0 2 -O 2 pZ - ry O 2 O H 0 0r 0 ~. ^. = 00 Z 0O N N0Z Oa -N •-• N b 47 47 N CO Y O P b Y 0 . .. W Y h P bNCO .47.n P 11'a Y ri 47 M .. 47 v> .O Y O ..% 1 CV ON. Y P co -4 . b h co .Op M h . b . .b.. .b-. ..a J IIP7 in 1 M HM N CI 47 b NNw0 LL a 7 WWWb b h h h Iti a Clf c. U O~ O O OZ 0 G NY 0 O, N O 0 0 0 0 0 0 O 0 O ... O b O W PP oO oO ° O O - -* O p O O O p O O O .. M 117 or 9 -o M 0 . -O 2 0 NV9 bM > O^ C. h OW MM 47 Ila CCO 9 pJ S 0 Y b .p p Y P Y vela n • co T v hhhhh hh va O M . In O d y A [Y C1l JE NhO W O 0 co 0 a rh 0 h 0 0u O Y N CO Y N N Y [ 0M NI Nf U N N N N M O ! >0000000000 a O Ls' .I i N M Z b Y - - 0 Z .. 0 0 CV47N N N C -0 A. 0 Nf - 0 O = O .-• 2 .- . - ..' r, M NJ N b 0 k 0P 0h 0 P 0 C4 CV 0 P CV b ^P . .; .o . a-si . .c 0, O 117 .r 01 Y 1> P .PT 2 C IA CO 0 O D O 0 0 JMM2 . 0 P 1.7 2 N h Y O P va .0... M ti P N N Y 47 O W h b W P O Ny YM N mm M .~-• .Y . . b N b M 2 OM C. O O "'• I.CI-. WO h ... Y P CO .. . •-• Y h N O N Y M W H N N M MMON N .0 .7 2 In20 t0 O MO W 0 O 0 OoPcW W N h hY 47 v> Y N Y Y 47 N M M CO 47 N N... 0 O co M O R .4 I o n 1.07 u, u, c O O o 0 0 ..2 ° 407 cm ° u, v O O 0 0 0 0p 0 0 N Na CO N NI O ... p OOoO 0 47 6 co 0 P O .-. y 0 0 q co ~ 0 0 0 0 0 O Y .... M O O 0 47 W va P W co W co co W O rry M NW M YN Y MC 4 M O P P O ry 0 4, P p 0 40 0 M rn LaWm. Q tn. Wrn T d 4 J W WM Mh M -0 P N 0 = CV Z CM. 0 0 O.4 NM Nf 0 MN 0 0 0 0 0 O 0 0 O OOO .b. M NN O^ M 6 O .. .-.■ 10 Oq0 0 0 0 0 00 000 M P .. Y PP PP CO N W -~ .. W co W .p W O vi Y In . .; .; 4 0 0 0 0 0 0 0 b- N O O b M W N co Y u, YN MN o N• = a o P o 0 0 0 0 0 O O - - O .. .. O O- O W Z .. O .-. Q N b b N n M M Iab M .P. O Oo O O O0OO O 47 OW h ry Ifa q vMW H < h b O P 0 h .... O N H M N _: N- N 0 O N O ."' W N .r C . N CV W O 0 0 0 0 0 0 OOOO . m0 1 d tlf O W h N . M1 P n Va m n CO m 4b7 .O O P b ICf b . . V7 In IIa In b O W 47 M co M b r. W Cy Z NZ N 0, N O O O O 0000 0 0 Y M M@ 1 .'f O O p 2 Y 0 MM z N .4 .4 . . va 4, ODO NN 00 .- . OO p . -o C3 a 0 0 0 00000000 0 - NryN O 0000 0 N ry N N N N N N 0 ICI CV N P W P r% P II'] .. N ICf N O , h i - O N M h 0 W .... .O P M 4"f P b N v9 P N 0- V7 47 .-. .O Y N- b H Y . . M .. h h h 47 47 Y Y . ; - U M in F CO W 0NNP 47 WY O M O Nf .. O. b . .. A b.• b hhi .b- . O b .O Y 4 47 WhN.7MCI H h M Y N 0M hN . . ^... ^ 2 . . O O P Nb 02 6= N N N N N O M O .0 •O O h . b h h hO .hh .y .. O ^ W 47 Y 47 b Z2 bP O T 47 47 N h h b b .O p .0 O h .-.N h W P M hb rt 0 W O M M Yy b b b b b b b b _O o ICr U' ICI 47 q U, .77 CV m W b va O b ., 2 2e N ■ . n s va .Y. b b b .O b O - 0 0 Z0h 0 ac h sr P .O 47 bO U, sr Y O O O 04 o h 2 CO In y le, N N.N CO O O .. h . m co W NN nm W NCON ry P W 6 >t o LCC O 1 Or.O sr ,c M N H m N C = O y lL J y 6 0 CI G U= ff- a W >- I .W I =0 Imo° 1s r C. N .N. N. N.. N p n 2 .C H o 0 --0 .O ri 9 b 9 .Op N O YON 0 O h O .. .O b O hz H k b v] Y b V7 Y In C. N- Yy ` N b N h NN hN h ~ m co 0 p ... 0 . M Y CM Y - 0.. M O W H b .W CT -O p0•P. P c P. p.M W0CO W 11'> O Q W > OO 4 [t7 H 47 b Y- 0 O O Y Ira O va - 47 Z v= z Y7 M C. CO b .O 1P n .O h 47 ICI CO 47 M O W MMH Y M M Y O UI b M .O M b II'a 47 h .1 Ay da T ¢in W J a J o Y .. nI W .r Y .p .p W .0 GO m O 9 1 C9 ▪O W U LL 0. NZ 0O OP 0 0• N 2 m m Cl 2 0' f n1 0 2 0 MI19 2 0• . b0N0In^ 2 Nb fa f 04,I N M M M Y9 N NM M NM MM M O 0 0• . IA 1h.'1 o M M M MO f 119 0 Vl O. b 0 b h O M M MMO 0 NO ZN In U, T MM 0. co ' N MM M M MP N 1 CO "D U M9 f-. N fM b 49 MMh Nh M O M b NNM M N 119 M M Nb M M M M M M M M M M M M M M M M Mp MVlOT N H M MM0O M bh f V9 M ff O' MM M MO 0• m .M m M fV9 MM 110•'9NN MMM MM M M Z 0 0. O. COg2O .ta O d CO p 0 0 0 0 C C g O CM C O C GI O 09 2 ca CO 0. m co CO S CO [a CO m Z CO • Z co O = ▪ Z Q Z m Z 22 y N m m .". • m . Z Z If'' Z Z a Z CO Z YY 2 4 v g J LL O ▪ O M 49 Z M .-r M ti 2 0• h OMM co Z N Z a Z 119 a h h A. M h N N MM0 1•J M M a J ... M O O O▪ O O 0 0 0 0 0 O O . y M Q 2 .h0 Z •IY 2 O N N g . Y2 . N 0 0 C. 0 0 0 0 0 0 C. C. 0 0 0 0 0 0 .OO c.. O y i Q N M M NC O 0 00 Va N h M.. I 0 0 .. •Cr N M mm 0 0 0 0 0 0 0 0N. 0 0 N h O Yl Ml 22 N =M N f 10 h CO 0 O a O O br O• 0M N N Vl M N N N ... Vl 2 0• P V9 0' '-'• .O O. H M N N O P. .M .. p Z Z0 q h y h NmO O O O O O O r .. . •119 H f 0 0 0 0 00 OO O OVl O pZCD A.. f Vl OOOO OOp p N 01 O f Y .0 Y O 0 0 0 0 C. N m M •a•• f VI .OP O f N ... N O .f T '• co C oo▪ 0 o O C. 0 0000 .0 h M ... O .0 V9 0 O 0 00 iC d y 0 .C .0 O 0 0000 0M . Mf yM . .. CO OV4 Irl f N N M NY M C.▪ O O O .hO O O . Y 4> m y 0 0 0°0oo a o O •h b CO n my P. Wm O0 h.. It co 0 P_ CAI +Q 6>0- y O N 0 o N 0 119 M N P N N0• Na NmM O M 0000 0 q0 0 0 0 H N MMM h M p . N .0 0 0 h N ▪ 0 q0 . .4 0 h 0 0 CM 0 V9 N 0 q0 0 0 0 0 m CON10 Na Nm NN N uO M f 00 0 0 0000 N` q O 0 0 N 119 o b 0' N f N ON 11'9 N .. 2ab b0 ba a b6 h 11'N 9f M a b 2COfCOa0 11'0•9 V9 Mh 00 000000 0 0 0 0 00 0 0 0 f f yO - N ▪ a mO Om 0O f O O O OfO f o OO . O .0 0 0 0 0 0 0 V9 0 0 0 0000 Of NM ", cc 0 0 0 0000 y y H.• Yl O m 0 m 0 rl' AO 0• U, 0• .1 b ti N f M .. . 0. p . . CM hM O0 p ~. ZU Vl f• 1l9 hM Mf f VlM 1A f O. bf N CV yNh h N Vl 0• M y . I M M M M 'M .4 M M M M M P. M .4 F9 M T m Cb. 0. 0 m MO h O N fV N N 0 •▪ a b 3 M M M O. O M Mf M M Na N O o R. M M O 11M9 V9 O .2 n n O h N f m 0• 0. T CO O IP! Vl 49 If9 O m Cf. N 0. . .. b NN h0 Na N ffU, Na N 0 hh m o 0• pOm CO p 0 0 0 O Q O 0 m0m 0 0 m 0 m 0 O• 0 0 d 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 J N V9 0 0 Vl 0 g -°~~ .S LL J ▪ W O X m h h f U, h 01 0 ms 04 0 S 0 Z 0 2 2 0• b 119 119 h C 2 h. G ZO O bm4 b b _ ▪ h. W t 00000 M O M MM NN N MNMNNNM N NM N N N NMNv.0.lNoN N N ryN NN 00000000O 0 0 0 000000 0 J J6 Q Q OM N M N 4, N0 O Z My O 4. O > p. 1~ W- CO Nco b NN b CM == N Na CM M 0• Nh N Nm M MOM •M M M N a OO O OOO00 00 0 0 0 0000 CONN 119 y .. f 1f. b0 M M h0 Mo -...A 1 M fO M NMO MM M •~' a m f aN • 01 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 •r I O 2 d Z O W J N z • 2 119 119 As M 0 O O 0 T O~ y 1... 10 o^ m T O• M M fb y 0= h M.. O OrO N.. O 0 000000000 0 0 00000 0 00 M -~ h 0 H N. a ■O 10 .0 CO ?0 rvC O0 .r S O O O O b 0. .y-. .M-. b 0 Vl 0 O 0 C. N O p d .~. .r 0 ... .-. . .-~ .r ~ -. O J . r N Z mm Y O Z 0 N N= a 0` O O N O. .. . N O' m 1 0 m^ m M M O• 1f~hO.7OO. O` O f 0• .7 y .V9 OO M _+ "'• N N ... r r3 Cl ... . .. N N .r N IV N N 0 M_ 0 I O 0 M C- V/ pbP m OM N M m m M 0. fO Vl Vl e v 11 9 C. A-2 0 Z q h m hl M N V9 0 0 .P m .. M 0. m h .O h CO h f H M M N M M rt M 4 a M ,4C M M H M M HaNz2 C M OCZCr Vl O 0• O qO o 2 My 4' Z0 O Z CO O Vl m C. to "'•^ J 2 ., CO r f .0 V9 0• NNaN f w 1 .. Q U O N Z=0 y 0. 1c, b N ® ., M 9 1 '9 m N0 Z 0Z Pf f M f 0a. M b OV) as b b b Vl a b a O m 119 O f b Vl Vl. 49. m Vl N 1n yj f119 -' N b af m Vl 49 a In Nf M 119 Vl f (n 0 W 1 1 J 17 1 1- m ['J ' Z 1 Vl AAn m Aso H y H ['J H O J. Z Z CO til W Z 2 m 2 y y 1 .. ff0 a .p a b O N N O nl1'9 b 0 bm m b 'O O b a 0 OO 2 q0 b h .N... N-. N a a -co h O. .h... .i h.. .h. . F. r, m® .0 CO CO CO P P P 0. T LL M LL N 119 LL O LL 'I? 2 LL LL O m N m ,. hh ^• bb0 O N b V] m .' .4 O O O f 02 N .- . h .-. N OM . M y N w a0 '0V9f m . Vl f N N M M N I.j N 0 OO 0• M N .-. 2 M V. M h P90' b N . ; .; a b 0 CO 0 a .0 M M .o .a 4, V9o=hw a a .'.0I19 m 0h.. CO ~. h0 h CO y .M~ h o CO =W 03 S W t 0 W c.. t 119 Ac .2 U, .. ygV m1 y V O tb 1=2g A ~ W [ 0. 48 w CM ..• . .. h' M n m O• W 62 W J J _ : .. . . ...O LOY .Z> [A J 1., 0 CO m 0 p. d LO > tll Appendix B-3 . Sea-Spray Corrected Concentrations for Major Cations and Anions . . -------------------------------------------------- LAKE NAME Ca Mg Na K 2CAT ALK S04 Cl ZAN EC/FA N DAVIS 151 .5 103 .1 102 .7 21 .6 379 .0 379 .9 8 .6 0.0 388 .5 0 .976 CULTUS 80 .8 46.6 31 .9 9 .5 168 .8 172 .2 5 .2 0.0 177 .4 0 .95 1 L .CULTUS 99 .5 69 .1 49 .3 10 .6 228 .5 .-_ irl 8 .9 0.0 227 .9 1 .003 LAVA 84 .0 100.9 115.5 30 .0. . 330 .4 324 .0 5 .2 0.0 L .LAVA - 95 .0 102 .5 93 .7 26 .2 317 .3 367 .8 0 .1 0.0 367 .8 HOMER 49 .2 80 .1 145.3 21 .6 296 .2 295 .4 4 .9 0.0 300 .2 0.987 ELK(AV6) 91 .4 463 '44 .0 14 .3 196 .6 199 .3 4 .1 0.0 203 .4 0 .966 DEVILS 49 .4 64 .7 85 .8 22 .3 222 .1 249 .5 6 .9 0.0 256 .4 0 .866 1 SPARKS 48 .0 35 .6 46 .9 13 .9 144 .4 132 .9 5 .1 0 .0 138.0 1 .046 TODD 61 .9 18 .6 45 .3 21 .7 147 .6 169 .3 5 .6 0.0 174 .9 0 .844 3 .9 1 .2 0 .0 6 .1 11 .2 2 .9 1 .1 0.0 4 .0 t 191 .8 160 .8 112 .2 28 .2 492 .9 526 .3 2 .6 0 .0 528 . 9 SCOUT 68 .2 61 .9 24 .9 17 .3 172 .4 179 .5 4 .1 0. 0 183 . 6 ROUND 114 .5 92 .7 14 .7 8 .3 230 .2 205 .1 0 .0 0 .0 205 . 1 CLEAR 178 .2 156 .8 135 .8 - 24 .9 495 .7 496 .5 41 .2 0. 0 537 . 7 DUFFY 76 .9 38 .1 20 .3 'N 3 .9 139 .3 117 .6 3.0 0. 0 120 . 6 NONICH 26.6 23 .5 11 .1 = 4 .7 66 .0 69 .2 0 .6 0. 0 69 . 8 RED BUTTE 64 .E 54 .3 BOO' 18 .9 196 .9 187 .3' 3 .9 0. 0 191 . 2 JORN 38.0 28 .2 11 .7 2 .9 80 .8 78 .5 1 .1 0. 0 7 . ' 71 .7 86 .6 23 .1 8 .6 190 .0 195 .4 0 .9 0. 0 BULL RUN(AV6) 68 .9 35 .3 25 .9 7 .7 137 .9 124 .0 0 .3 0.0 LOST(AVG) 49 .8 26 .7 9 .2 8 .6 94 .3 83 .4 1 .5 0. 0 FRO6 43 .6 27 .6 29 .4 5 .7 106 .4 108 .9 1 .9 0 .0 110 .7 0 .'iti ~ CLEAR 74 .4 58 .1 23 .2 7 .7 163 .4 167 .7 0 .0 0.0 167 .7 t - i N .SUMNIT(AV6l 10 .0 5 .7 2 .3 4 :9 22 .8 2 .B 11 .1 0 .0 13.9 1 .647 BAYS 3 .9 2 .1 0 .0 '0.7 6 .7 5 .2 ND ' . -- t SCOUT , 3 .5 0 .0 0 .0 0 .8 4 .3 7 .5 0 .0 0. 0 X7 .5 5 ROCK 36 .9 0 0•.0 0 .7 37 .7 2 .1 4 .8 0 .0 0 .7 ND ND 17 .8 1 .420 335 .5 0 .97 7 LUCKY(AV6) BLUE(AV6) SANTIAM *- - , 0 ..0 ' (POND} '3 .4 0 .0 0 .0 4 .0 7 .4 WALDO 10 .8 3 .9 1 .5 9:1 25 .3 16 .9 1 .0 0.0 332 .2 3.3 0. 0 ODELL 142 .4 : 77 .8 117 .2 '20 :3 327 .8 CRESCENT 118 .6 71 .3 53 :9 31 .9 275 .7 '329 . ,1 .004 , t Corrected ion balance not meaningful due to some negative values,' 49 ratio cOumn . - ' ' } 4 lt ` ~&I,9t' 14 t' t 2 .2 0 :0 ' 284 ..4 .01.969 282 .1 --------------------------------- --------- - ---------------------------------------------------------- 1-Units for all tabulated parameters are (ueq/11 except for cation/ta i _ ,0•,, " Tr ;' 6-'P . ii i .f_ I 7 ~ ~~ r L Appendix B-3 . Continued . LAKE NAME Ca Mg Na K SCAT ALK S04 CI ZAN .C/FAN -------------------------------------------------------------------------------------------------------------- SUMMIT(AV6) 6 .0 2 .0 3 .0 6 .7 17 .6 11 .9 1 .8 0 .0 13 .7 1 .286 BETTY(AY6) 14 .6 4 .1 10 .3 7 .7 36 .8 32 .8 3 .6 0 .0 36 .5 1 .008 CHARLETON 23 .6 12 .6 8 .5 53 .7 47 .6 3 .0 0 .0 50 .7 1 .060 TORREY 38 .4 24 .4 21 .0 9 .2 93 .0 82 .9 6 .3 0 .0 89 .2 1 .04 3 WHIG . 99 .2 49 .4 42 .9 18 .6 210 .1 182 .3 8 .3 0 .0 190 .6 1 .103 WAHANNA 20.0 16 .5 13 .6 -11 .0 61 .1 54 .2 6 .1 0 .0 60 .3 1 .01 5 S .RI6DON 4 .9 1 .6 0 .0 14 .8 21 .4 8 .1 3 .7 0 .0 11 . 8 N .RI6DON 26.9 11 .0 17 .9 • ND 43 .2 ND ND -- KIWA 32 .4 16 .0 20 .0 ND 50 .8 ND ND GOLD 176 .8 98.2 106 .9 30 .7 412 .5 421 .3 8 .2 0 .0 429 .5 0 .960 U .MARILYN 79 .3 31 :8 39 .7 •11 0 .0 160 .8_ 190 .1 6 .3 0 .0 196.4 0 .81 9 L .MARILYN 84 .4 30 .7 29 .5 7 .5 152 .1 180 .8 6 .1 0 .0 187 .0 0 .81 3 OLALLIE(AVG) 10 .0 7 .3 1 .7 4 .4 23 .5 15 .8 1 .0 0 .0 16 .8 1 .398 MONOD 10 .8 6 .8 4 .0 10 .4 32 .0 26 .4 4 .0 0 .0 30 .4 1 .052 HORSESHOE 6 .5 2 .9 1 .4' 4 .6 15 .4 13 .3 0 .0 0 .0 13 .3 t GIBSON 3 .0 1 .4 0 .0 3,4 7 .8 2 .9 0 .0 0 .0 2 .9 t BREITENBUSH 21 .5 :8 .7 14 .0 51 k . 49 .3 46 .1 1 .5 0 .0 47 .5 1 .03 8 FIRST 11 .8 5 .2 0 .0 1 .2 18 .1 10 :4 0 .7 0 .0 11 .1 t 7 .7 , 4 .6 0 .0 : 1 .4 13 .7 7 .8 0 .0 9 .0 7 .8 t LOWER 36 .7 10 .9 A .9 2 .5 55 .0 57 .5 0.0 • 0 .0 FISH 123 .3 38 .3 . -21 .4 . ,10.' .493 .7 206 .4 3 .3 0 :0 209 :7 SHEEP 26 .8 0 .2 0 .0 14 .3 41 .3 8.'8 0.0 0 .0 .8 . 8 WALL 10 .1 0 .0 0 .0 21 .2 31 .4 9 .5 0 .0 010 4 7.9 .5 t AVERILL 10 .9 0 .0 23 .8 34 .7 18.6 0.0. 0 .0 , .18 .6 t RED 24 .8 0 .0 0.0 9 .0 33 .8 15 .6- 0 .0 0 .0 15 .6 1 BROOK 138 .0 59 .6 0 .0 9 .9 207 .5 270 .7 0 .0 0 .0 270 .7 JUDE 186.2 106 .9 78.3 16 .2 387 .6 375 .9 5 .7 0 .0 381 .6 1 .01 6 RUSS ,131 .2 55 .4 58 .1 11 .8 256 .4 267 .4 3 .4 -9 :0 270 , 0 .94.7- LAVA CAMP 10 .0 15 .3 # .0¢' 3 .1 29 .4 27 .2 2 .3 0 .0 - . : 29 .5 0 .995 SCOTT 13 .5 16 .1 8.t' 41 .7 41 43 0 .9 0 .0 42 .2 •10 .98q THREE CREEKS 84 .2 56.0 `-r4 .1 • 13 .0 213 .5 " 0 .0 0 .0 213 .5 t HEAD 9 .0 ` 59 .9 213 .1 -t-, 1-Units for all tabulated parameters are (ueq/1) except for cation/anion ratio column . t Corrected ion balance not meaningful due to some negative values . g.51 .924 • 'Y - t ti APPENDIX C DISCUSSION ©F EXPERIMENTATION IN LABORATORY TECHNIQUE S In addition to those analyses performed to achieve the primary objective s of this study, additional laboratory experiments were performed to "shed mor e light" on both the current differences in analytical . procedures used among acid-precipitation researchers and the inconsistencies in comparin g historical alkalinity data to recent data collected using Gran titration t o determine the alkalinity titration endpoint . The results of thes e experiments are summarized here . The Gran titration procedure, or total inflection point (TIP) procedure , is described in detail by others (Gran, 1952 ; Stumm and Morgan, 1981 ; Zimmerman and Harvey, 1978-79) . This procedure is generally accepted as th e most rigorous and accurate method for determining alkalinity titratio n endpoints and has been used by most investigators since 1970 (Kramer an d Tessier, 1982) . Before 1970, alkaliniti .es were determined using fixe d endpoint (FEP) acidimetric titrations . There seems to be considerabl e difficulty and inconsistency when investigators compare present TI P alkalinity data to historical FEP data in order to assess extent o f acidification for a water body . In the past, FEP alkalinities wer e determined using either colorimetric endpoint indicators or a fixed pH as a n end point indicator (Kramer and Tessier, 1982) . The endpoint pH for a tota l alkalinity titration is, however, an approximation of the f = 0 equivalenc e point of the carbonate system . The equivalence point varies with inorgani c carbon concentration ; a lake high in inorganic carbon and well-buffered ha s an equivalence point of approximately pH = 4 .5 . A dilute lake, however, ha s a higher equivalence point pH (>5 .0) . Hence, FEP alkalinity titration s generally overestimate the alkalinity of dilute, poorly buffered lakes--thos e which are sensitive to acidic inputs . Rigorously, the magnitude of thi s overestimate is the amount of hydrogen ions titrated past the equivalenc e point to reach the fixed endpoint . Jeffries and Zimmerman (1980) report that mathematical correction of FE P alkalinity data is not possible, as FEP data differ randomly from TIP data . Other investigators report that accurate corrections of historical data ar e possible . However, the magnitude of such corrections is inconsistent amon g investigators . Kramer and Tessier (1982) report a methyl orange endpoint pH , as determined by three independent operators, of 4 .04± 0 .10 (n = 24) . Thus , he suggests that historical alkalinity data, for which methyl orange has bee n used as the titration endpoint indicator, should be corrected by 81 ueq/I . Kramer and Tessier describe this correction as the excess hydrogen io n concentration resulting from the difference between their own methyl orang e endpoint pH and an approximate equivalence point pH of 5 .0 for low-alkalinit y solutions . 1 51 Most other investigators report fixed endpoint alkalinity titration dat a corrections of 32 ueq/l . Burns et al ., (1981) report that a colorimetri c indicator overestimates alkalinity by the hydrogen ion concentration at th e titration endpoint . Thus, they report a correction of 32 ueq/l, which the y describe as the hydrogen ion concentration at pH = 4 .50 . Rigorously, such a correction exceeds the theoretical correction by the hydrogen io n concentration at the titration endpoint . This concentration is, however , small ; the more dilute a system is the lower will be the endpoint hydroge n ion concentration . Henricksen (1979) reported that if alkalinities ar e determined by standard titration to pH = 4 .5, they are overestimated by 3 2 ueq/l--the hydrogen ion concentration at pH = 4 .5 . Haines (1982) mad e extensive comparison of fixed endpoint and Gran titration alkalinties an d reported that the two methods give linearly-correlated (r = 0 .998) result s with a slope of 1 .0 and an intercept of 32 ueq/l (ALK Gran=ALI(FEp -32) . It i s not reported, however, whether the fixed endpoint alkalinities wer e determined potentiometrically or colorimetrically . Finally, Hendrey et al . , (1980) reported that determination of alkalinities using fixed endpoint titration to pH = 4 .5 requires 30 to 40 ueq/l excess titrant . In this study, alkalinity titration endpoints were determined using th e Gran technique . From the raw titration data, fixed endpoint alkalinitie s based on endpoint pH values of 4 .5 and 4 .0 were also calculated . Linea r regressions of these alkalinities versus the correspondin g Gran-titration-alkalinities are shown as follows : ALK ALK Gran = 0 Gra n = 0 .96 ALK 4 .5 -31 .20 (n = 63, r 2 = 1 .00) (C-1 ) .93 ALK 4 .0 -91 .9 9 (n = 63, r 2 = 1 .00) (C-2 ) These regressions indicate quite favorably that fixed endpoin t alkalinities can be corrected easily and accurately if the endpoint pH fo r the historical alkalinity data is known . In addition, these corrections correspond closely to the corrections reported by others (and describe d earlier) for the same titration endpoint pH values . Generally, when fixed endpoint a l ka l i : n 1i. ty ti tra- i ons' were performed usin g a specific endpoint pH, this'pH is readily available with, the historica l data ; corrections are thus simple . Correction of data where FEP alkalinitie s are determined using a colorimetric indicator is more difficult, however . The pH at the methyl orange endpoint is not generally agreed upon and ma y actually occur over a range of pH values, depending on the strength an d amount of methyl orange added . Thus, historical alkalinities determine d using methyl orange as an endpoint indicator cannot be as easily an d accurately corrected . In this study, the methyl orange endpoint wa s "investigated" and did not appear to be distinct ; the color change from yellow to pink was gradual . 52 Equations C-1 and C-2 indicate that accurate corrections of fixe d endpoint alkalinity data can be made . Differences among analysts, reagants , titrators and pH meters, however, might decrease the accuracy of suc h corrections . To explore the effect of such differences, the alkalinities o f 16 lakes sampled in this study were compared to alkalinities of the same 1 6 lakes as determined In 1975 by Shulters (1975) . These past alkalinities wer e determined using potentiometric fixed endpoint titration to pH = 4 .5 . Th e linear regression of these data sets is shown as follows : .7 ALK ALK Gran = 0 .95 - 25 FEP (n = 16,r = 0 .98) (C-3 ) where the Gran alkalinity values are from this study and the FEP alkalinit y values are those of Shulters . The closeness of this regression to that of Equation C-1 for a fixe d endpoint pH = 4 .5 is impressive . The historic fixed endpoint data wer e determined using less sophisticated equipment and there was a seven-yea r interval between sampling of the lakes . Natural fluctuations in alkalinitie s due to different sampling dates, seasons, times of day and differen t precipitation patterns could easily explain the slight difference i n Equations C-i and C-3 . In this case, an accurate correction of historica l fixed endpoint alkalinity was possible . Oregon Cascade lakes are weakl y buffered by the carbonate system . The effect of the presence of other buffe r systems on the proposed corrections is not known . To study the extent of alkalinity deterioration with sample storage time , alkalinity analyses were performed weekly on water samples from two lakes . The average alkalinities of these two lakes, as determined from 9 and 7 samples collected during the summer of 1982, were 125 ueq/I and 16 ueq/l , respectively . The water samples were collected in one liter linea r polyethylene sample bottles, filtered through 0 .45 um Millipore filters, an d refrigerated at 40 C between analyses . The results of this experiment ar e shown in Figure C-1 . It is evident from Figure C-1 that alkalinity does not change significantly with time and that linear polyethylene sample bottles d o not influence alkalinity . Finally, both in-situ and laboratory-equilibrated pH data were collecte d in this study to investigate the effects of differences in conditions unde r which pH data has been historically collected . The mean in-situ pH for th e 63 lakes was 6 .93, with s = 0 .80 . The mean lab pH was 6 .96, with s = 0 .59 . Thus, there was more variability in in-situ pH, but the mean values wer e nearly the same . Lab pH data were regressed as a function of field pH an d the regression forced through the origin to obtain : Lab pH = 1 .003(field pH) (n =63, r 2 = 0 .82) (C-4 ) Although there is greater variation in in-situ pH because of natura l influences which are largely missing in the laboratory (primary production , 53 r 0 CD S0 4-3 N s_ a) 4 ) a) co 0 >, 1-0 0 0 •r 4-) 5 (C) r s_ a) 0 r •r S_ r a) 4-3 a) • r a) ~S4-3 •r IS) U) U, N n U, U) (1/ ban) Al I N 11V>i1 V 54 U, N m respiration, temperature effect and wind-driven . C0 2 supersaturation), It appear s that pH data collected under both conditions can be compared without correction. . The conclusions of these experiments are : 1. Excellent correlations were obtained between Gran-titration alkalinit y data and fixed endpoint alk-alinities calculated from the raw titration, data . The correlations obtained were.simi,lar to those reported- by many other investigators . 2. Differences in Gran-titration alkalinities of 16 lakes sampled in thi s study and fixed endpoint alkalinities for the same 16 lakes sampled in 1975 wer e very similar to those differences predicted by the correlation betwee n Gran-titration and fixed endpoint titration alkalinities . Any differences ar e probably due to natural alkalinity fluctuations over the seven-year interva l between sampling . 3. Alkalinity does not seem to change significantly with time (less than 5 weeks) for filtered water samples stored in polyethylene sample bottles at 4 ' C . 4. Differences between average in-situ pH and averag e laboratory-equilibrated pH were not significant, although there was greate r variability among in-situ pH values . 55 March 5, 1984 ERRATA SHEET WRRI-85 : "Sensitivity of Oregon's Cascade Lakes to Acid Precipitation " by Peter O . Nelson and Gregory K . Delwlch e September 1983 USDI Project No . A-061-ORE ; NTIS Accession No . PB8 4 11178 0 Page1 Paragraph 5, line 3 reads . . . .less than 20 ueg/ l should read . . . .less than 20 ug/ l Paragraph 5, line 4 reads . . . .300 mg/ I should read . . .300 ug/ l Page 1 0 Table 1 . Under "Parameter" column, line 14 reads . . . .A1, ug/ l should read . . . .Al, ug/ l Paae 1 6 Under "Alkalinity" paragraph, line 1 0 reads . . . .ALK = -9 .10 + 1 .05 ECA T should read . . . .ALK = -8 .66 + 1 .05 ECAT Page 19 M .' Under "Summary of Metal Results" paragraph Line 3, reads . . . .ALK = -9 .10 + 1 .05 ECA T should read . . . .ALK = -8 .66 + 1 .05 ECA T Page 2 1 Paragraph 3, line 1 reads . . . .carbon analse s should read . . . .carbon analyse s Paragraph 4, line 4 reads . . . .an expotenta l should read . . . .an expotentla l Page 24 Paragraph 2, line 3 reads . . . .of 20 0 should read . . . .of 100 Page25 Figure 6 . Key -- #10 reads . . . .Theoretical (200 ) should read . . . .Theoretical (100 ) rage28 Paragraph 3, line 7 reads . . . .with Henricksens' s should read . . . .wlth Henricksen' s Page 29 Table 3 . Under "Source" colum n Line 3 read . . . .Logan et al . , should read . . . .Logan et al ., 1982 Note : word processor put date in "Region" category r