WSP02220

• File Number: 8281.400
• Description: Colorado River Studies and Investigations -- Colorado River Depletion Projections
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1993
• Author: Soil Cons Serv
• Title: Final Environmental Impact Statement - Moapa Valley Unit - Nevada - Colorado River Salinity Control Program
• Water Supply Pro - Doc Type: EIS

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Adjudi~ated water rights in Moapa Valley were established in ~905
and further adjudication was provided in 1920. The court decree
of 192Q established a summer and a winter season and established
the duty of water for the two seasons. The duty of the water was
set ati~.O cfs for each 70 acres for summer season and ~.O cfs
for ea~h ~OO acres for winter season.

Decreed water rights of 3.488 cfs summer flow and 2.6698 cfs
winteriflow have been awarded on lands above the Moapa Gage. The
area f~om the Indian Reservation to the Narrows has decreed water
rightsiof 4.53176 cfs summer flow and 3.~8646 cfs winter flow.
Irrigation water in the Lower Moapa Valley has been decreed to
the Muddy valley Irrigation Company. This right amounts to
36.2874 cfs summer flow and 45.4~5 cfs winter flow. The Overton
Wildlife Management Area (OWMA) also has a junior right for 25
cfs tOiirrigate crops and maintain habitat for wildlife.

The Mu~dy Valley Irrigation company has about 350 stockholders
and serves about 2,570 irrigated acres currently. There are two
types pf Company water stock. The owners of 2,430 shares of
Prefer~ed stock get all the summer water and one-half the winter
water.' There are 5,490 shares of Common stock that get one-half
of the! winter water. The OWMA owns about 42 shares of preferred
stock and about 81 shares of common stock.

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Water ~udqet

Water records for the period of ~979 to 1989 were used to
determine average annual values for present conditions. Total
averag~ annual inflow to the study area is 49,300 acre-feet.
crop cpnsumptive use is 23,500 acre-feet. Non-crop uses (mainly
phreat~phytes and evaporation) account for 10,900 acre-feet of
use an~ municipal and industrial uses account for 3,200 acre
feet. . The remaining 11,700 acre-feet leaves the study area.
Surfac~ outflow is 6,100 acre-feet and sub-surface outflow is
5,600 acre-feet.

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A summ~ry of water supply and depletions for Muddy River is given
in Table 3 for present conditions. Figure 6 is a composite Flow. J
Diagram for the Moapa Valley for present conditions.

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