The Central Nebraska Public Power and
Irrigation District Groundwater Mound Study
Purpose
● Main Objectives
 Evaluate the groundwater mound in the vicinity of lands
irrigated by CNPPID facilities
 Provide an understanding of the temporal and spatial
changes of the groundwater mound
 Identify factors affecting the groundwater mound
Key Terms
● CSD Groundwater Level Monitoring Reports
 UNL-Conservation and Survey Division
`
Key Terms
● CSD Wells
 Database of water levels from wells used in CSD report
Key Terms
● Study Area
Groundwater Mound Study Recap
● Estimated Mound Volume
 CSD well method
 Water balance method
● Subareas
● Spatial and Temporal Movement
● Adjustment Impact
 Diversions
 ET
Groundwater Mound Size and Shape
Annual Groundwater Mound Volume
Water Balance
Groundwater Evaluation
Water Balance
CSD Mound Volume Compared to Water Balance Mound Volume
Mound Volume
Calculated using
the Water Balance
Mound Volume
Calculated using
CSD Well Data
Water Balance
Adjusted Diversions Annual Groundwater Mound Volume
CSD Well Data
125% Diversions
75% Diversions
100% Diversions
50% Diversions
25% Diversions
No Diversions
Water Balance
Adjusted ET Annual Groundwater Mound Volume
95% ET
98% ET
102% ET
Un-Adjusted ET
105% ET
CSD Well Data
Primary Conclusions
● Groundwater Mound Size and Volume
 Increasing trend from the 1950s to 2000.
 No longer an increasing trend since 2000.
The Future of the Mound
● Declining Surface Water Recharge
 Reduced Water Supply in Lake McConaughy (Allocations)
 Increased efficiencies (Conservation)
• 1950-2000 average recharge = 145,000 af
• Since 2000 average recharge = 90,000 af
● Declining Mound
 Negative Water Balance
Canal Flow vs Precipitation
300000
20
18
250000
16
200000
Canal Flow, af
12
150000
10
8
100000
6
4
50000
2
0
0
1990
2002
Growing Season Precipitation
2012
Diversions
Deliveries
Growing Season Precipitation, inches
14
40
350,000.0
35
300,000.0
30
250,000.0
25
200,000.0
20
150,000.0
15
100,000.0
10
50,000.0
5
0.0
0
6 Month Rainfall
Canal Diversions, af
6 Month Rainfall, in
400,000.0
1942
1945
1948
1951
1954
1957
1960
1963
1966
1969
1972
1975
1978
1981
1984
1987
1990
1993
1996
1999
2002
2005
2008
2011
2014
Irrigation Diversions, af
Irrigation Diversions vs 6 Month Rainfall
Historic Impact of a 25% Reduction of Diversions
5,000,000
4,500,000
Annual Groundwater Mound Volume (Acre Feet)
4,000,000
3,500,000
3,000,000
2,500,000
2,000,000
1,500,000
1,000,000
500,000
0
2013
2012
2011
2010
2009
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
Year
CSD Mound Volume
Water Balance Mound Volume- Historic Diversions
Comparison of the water balance mound volume with adjusted diversion volumes.
Water Balance Mound Volume - 25% Diversion Reduction
2170
2165
2160
2155
Elevation (NGVD 29 MSL)
Declining Trend Matches Central’s
Observation Well Data
2180
2175
2150
2145
Apr/2014
Apr/2013
Apr/2012
Apr/2011
Apr/2010
Apr/2009
Apr/2008
Apr/2007
Apr/2006
Apr/2005
Apr/2004
Apr/2003
Apr/2002
Apr/2001
Apr/2000
Apr/1999
Apr/1998
Apr/1997
Apr/1996
Apr/1995
Apr/1994
Apr/1993
Apr/1992
Apr/1991
Apr/1990
Apr/1989
Apr/1988
Apr/1987
Apr/1986
Apr/1985
Apr/1984
Apr/1983
Apr/1982
Apr/1981
Apr/1980
Apr/1979
Apr/1978
Apr/1977
Apr/1976
Apr/1975
Apr/1974
Apr/1973
Apr/1972
Apr/1971
Apr/1970
Apr/1969
Apr/1968
Apr/1967
Apr/1966
Apr/1965
Apr/1964
Apr/1963
Apr/1962
Apr/1961
Questions?