WSP09828

• File Number: 8276.852
• Description: Moapa Valley Subevaluation Unit - Colorado River Salinity Control Project
• State: NV
• Basin: Colorado Mainstem
• Date: 6/1/1980
• Title: USDA Salinity Control and Environmental Assessment
• Water Supply Pro - Doc Type: EIS

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SUMMARY

Moapa Valley Subeva1uation Unit,' Nevada, is the first part of the study

of Virgin River Unit in Arizona, Nevada and Utah. See the report cover and

Figure 1. The study is being conducted by the USDA to identify alternative

solutions for reducing salt loading of Colorado River from irrigation and

other diffuse salt sources.

Muddy River flows through Moapa Valley into Lake Mead. Moapa Valley

is divided by the "Narrows" downstream of Glendale. Upstream of the Narrows

the area is commonly known as "Upper Moapa Valley", and downstream the valley

is known as "Lower Moapa Valley." The amount of'land irrigated varies from

year to year. The irrigated acreage is 4,982 with 2,060 acres in Upper Valley

and 2,922 acres in Lower Valley.

The existing condition was evaluated a~d three levels of salt reduction
were analyzed: Future Without Project, Alternative 1, and Alternative 2.
The benefits and costs associated with these proposals are summarized in
Table 2, page 1x.

Muddy River is estimated to contribute an average of 73,400 tons of

salt and 385,000 tons of sediment to Lake Mead each year. A future reduction

of 19,500 tons of salt could be accomplished by: (1) improving the irrigation'

delivery system to reduce canal seepage (1,835 tons), (2) improving water

management by increasing onfarm irrigation efficiency from 45 to 61 percent

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