WSP04272

• File Number: 8277.600.10
• Description: Big Sandy River Unit - Colorado River Salinity Control Program
• State: WY
• Basin: Colorado Mainstem
• Date: 3/1/1989
• Title: Planning Report Concluding the Study on Big Sandy River Unit - Wyoming
• Water Supply Pro - Doc Type: Report/Study

SUMMARY (Continued)

irrigators in southern California, especially in the Imperial
Valley, and in Arizona.

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Estimated 1986 total damages from. Colorado River salinity average
$310.8 million annually based on the 1976-85 average level of
river salinity and the 500 mg/L baseline value.

Historical salinity concentrations fluctuate annually with the
total basin water supply, but as the Upper Basin States continue
to develop their compact apportioned water', salinity levels will
increase at Imperial Dam. Between 1949 and 1970, the general
trend of concentration at the dam has been upward, but since 1970
salinity levels have decreased because of several years of high
runoff. Without water quality improvement projects, this
temporary downward trend will reverse itself when hydrologic
conditions return to more normal levels and as upstream
development occurs. Reclamation projections show salinity at the
present level of development should normally vary between 635 and
1,035 mg/L, with an average of 820 mg/L.

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In response to the Federal Water Pollution Control Act and its
amendments (Public Law 92-500), the seven Colorado River Basin
States in 1972 adopted, and the Environmental Protection Agency
approved, numeric salinity concentration criteria for three
points on the Lower Colorado River. The goal of the salinity
control program is to maintain concentrations at or below these
criteria.

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The Soil Conservation Service and the Bureau of Reclamation
salinity control measures are removing 156,800 tons of salt
annually from the Colorado River system. Over a million tons of
salt per year will need to be removed by the year 2010 to
maintain average salinity below the numeric criteria level of
879 mg/L at Imperial Dam. Even at this level of salinity
reduction, there will still be temporary but significant
increases beyond 879 mg/L due to natural variations in climatic
conditions and water usage.

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Early Reclamation Studies

Reclamation began studying the salt loading mechanisms
along the Big Sandy River in 1972 with the installation of a

The waters of the Colorado River are divided by the
Colorado River Compact of 1922, agreed on by the seven Colorado
River Basin States (Arizona, California, Colorado, Nevada, New
Mexico, Utah, and Wyoming).

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