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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at l~ast four separate canals. A Parshall flume is located in
the outlet works of Bowman Reservoir to measure outflow.

The ~uddy Valley Irrigation Company operates Wells siding
Divetsion and Bowman Reservoir. The company has about 350
stockholders and serves about 2690 irrigated acres. The
irriqation company operates a rotational system, providing water
every seven days from February 15 to November 15. From November
15 to February 15, the system is operated on a call basis. The
rota~ion frequency is about right for May-August but results in
inefficient irrigations the rest of the year.

An analysis using the average of 10 years of inflow and outflow
strea~ volumes indicates that the annual irrigation efficiency is
abouti 54 percent with runoff of 13 percent and deep percolation
of 33' percent. However, irrigation efficiency was about 16
percent during January and February with about 76 percent of the
appli~d water going to deep percolation. Excessive winter
irrigations are also reflected in ten neutron probe soil moisture
monitoring sites where data has been collected for two years.

The N~vada Department of Wildlife has a diversion located between
Overtpn and the USGS stream gage located just above Lake Mead.
This aiversion supplies water to about one half of the Overton
Wildlife Management Area's wildlife food crops and ponds. The
OWMA ~as a right to divert up to 25 cfs. They may divert 2,247
acre-teet annually for use on approximately 562 acres between
highw4Y 169 and Muddy River. They also own approximately 42
prefe~red shares and 81 common shares of Muddy Valley Irrigation
Company water.

The cQmposite crop distribution of the 4,865 acres of presently
irrigated land in the entire study area is:

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~O% pasture,
29% alfalfa,

17% barley for grain,
4% barley/sudan grass/other.

The av~rage irrigation efficiency for the irrigated acres in the
entir~ study area is estimated to be 55 percent. A leaChing
fraction of ten percent is required in Upper Moapa Valley and
Meadow'Valley Wash areas. In Lower Moapa Valley 15 percent is
requir~d to maintain production. This requirement is met by
normal! deep percolation.

Conservation practices presently applied on irrigated and
adjace~t lands include:

Brush Management
Conser~ation Cropping Sequence
Crop R~sidue Management
Irrigation Ditch and Canal
Lining
Irriga~ion Field Ditch
Irrigation Land Leveling

Irrigation pipeline
Irrigation Water Management
Pasture and Hayland Management
Pasture and Hayland Planting
structures for Water Control
Wildlife Wetland Habitat Manageme.
Wildlife Upland Habit ManagementJ

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