PROJ00495

• Contract/PO #: C153678
• Contractor Name: Lower Arkansas Water Management Association
• Contract Type: Loan
• Water District: 67
• County: Prowers
• Bill Number: SB 96-124
• Loan Projects - Doc Type: Feasibility Study

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by utility records for these years. Power coefficients are simply the amount of electrical
energy used in pumping one acre-foot of water; a power coefficient of 135 kwh/ac-ft for a
particular well, for example, indicates that it takes 135 kilowatt-hours to pump one acre-foot
of water through that well. Since the remaining wells were equipped with totalizing flow
meters in 1994, only incomplete data were available for them. The pumping from these
metered wells was estimated at 11.11 percent of the pumping from the power coefficient
wells, based on the data that were available for 1994. Obviously, the separation between the
wells in the main stem area and the wells out of the main stem area was based on well
location.

During water years 1986-94, the irrigation pumping averaged 62,206 acre-feet
annually, and ranged from 23,194 acre-feet in 1987 to 91,328 acre-feet in 1991. An average
of 60,547 acre-feet annually, or 97.33 percent of the total occurred in the main stem area.
Table 2 shows the breakdown of the main stem irrigation pumping between supplemental and
sole-source water. The supplemental water averaged 44,586 acre-feet annually or 73.64
percent of the total main stem irrigation pumping, and ranged from 14,387 acre-feet in 1987
to 68,027 acre-feet in 1991. The sole source water averaged .15,962 acre-feet annually, and
ranged from 8,188 acre-feet in 1987 to 24,385 acre-feet in 1994. The pumping in individual
years shows considerable variation, most of which was caused by climatic and hydrologic
factors. The amount of surface water available to the ditches and reservoirs was probably
the single most important factor in determining the amount of supplemental pumping.

Water years 1990-94 were selected as a representative analysis period in this study.
The pumping during this period is judged as larger than normal in that it includes two years
of relatively high pumping (1991 and 1994) and no years of low pumping. Studies prepared
for the Colorado Division of Water Resources for use in Kansas v. Colorado indicate that
pumping by LAWMA's membership was probably larger during the extreme drought conditions
of the 1970's; however, several institutional factors have changed since then that will reduce
pumping, even during a repeat of those drought conditions. Included among these
institutional factors are the implementation of the 1980 Operating Plan at John Martin
Reservoir, the implementation of the Pueblo Reservoir Winter Storage Program2.J , and more

2.J The Pueblo Reservoir winter storage program affects the operation of the ditches and reservoirs
that divert upstream from John Martin Reservoir during November 15 through March 15. Water that
historically was used for irrigation is stored in Pueblo Reservoir and the private off-channel reservoirs,

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