WSP00431

• File Number: 8271.200.60
• Description: Colorado River Basin Salinity Control Program - Development and History - Ann Rpts-Reviews
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 12/1/1984
• Title: 1984 Review - Colorado River Salinity Standards
• Water Supply Pro - Doc Type: Report/Study

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forth numeric criteria for salinity and a plan of implementation

for salinity control. After regional public meetings by the

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Forum the report was adopted by the Forum and recommended to

each of the seven states for adoption by the states as the

state standards for salinity. Subsequently, each of the

seven Basin States adopted the numeric criteria and the plan

of implementation, the state standards were approved by EPA.

Section 303 of the Clean Water Act of 1977, requires that

water quality standards be reviewed at least once every 3 years.

Reviews were made by the Forum in 1978 and 1981. The 1984 re-

port being considered today was prepared under the provisions

of Section 303.

The Colorado River Basin covers some 242,000 square miles
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of watershed. The Basin is divided at Lee Fer~y, separating

the Upper 3asin from the Lower Basin. The major points of

concern fo:c which numeric criteria have been set are at

Hooverr Pa:cker, and Imperial Darns, the major diversion points

for water users in the Lower Basin.

The ri\'er has had a history of generally increasing sali-

nity since continuous records were kept, sometime in the early

1940's. T~is increasing trend is almost continuous until 1970.

At that point salinity leveled off and a slight decline has

been experlenced since 1972. It appears that the downward

trend may ;-.ave ceased. However, recent high flows in excess

of demands have resulted in a significant decrease in sal~nity
concentrations as a result of dilution.

There has been a change in salinity at the three stations

between 1972 and 1983. The 1972 levels are the adopted numeric

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