WSP12020

• File Number: 8272.500
• Description: Colorado River Basin Salinity Control - Colo Dept of Public Health - WQCC and WQCD
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 9/15/1976
• Author: Dept of Health -WQCC
• Title: Colorado River Salinity Standards
• Water Supply Pro - Doc Type: Report/Study

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..* THE PUIUC RECORO ("ORPOAA TION
ALL alGHTS aESE'VEO

3.9.7

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Page 3

STATEMENT OF BASIS AND PURPOSE

A review of the water quality standard for salinity in the Colorado
River and the plan of implementation has been held in accordance with
the ~olorado Water Quality Control Act and the Clean Water Act. The
same water quality standard is adopted for salinity--the water charac-
teristics within the Colorado River basin in Colorado appropriate to
maintain the numeric levels established at the three downstream check-
points. The purpose of water quality standards is to protect the uses
of. the waters, The narrative criteria adopted by Colorado will ade-
quately protect the uses. It has been the consensus of EPA and the
Forum for some time that the numeric levels are appropriate.

The standard rests upon the dual considerations that salinity levels
shall be maintained in the lower Colorado River while the upper ba~in
states continue to develop their compact-apportioned share of theColo-
rado River, These were recognized as necessary companion considerations
even before the 1972 amendments to the Federal Water Pollution Control
Act were adopted. See, for example, the Conclusions and Recommendations
of the Conferees at the Reconvened Seventh Session of the Conference in
the Matter of Pollution of the Interstate Waters of the Colorado River,
page 3 of Exhibit C to the 1975 Forum proposed Water Quality Standard
for Salinity and Plan of Implementation. The 1975 document was Exhibit
A at the hearing.

The points ehosen as appropriate for establishing numeric criteria are
three key locations in the lower mainstem. The 1975 document affords
a clear explanation for the choice of the three locations at pages 55
and 56:

In order to provide for sound water quality 'objectives,
numeric criteria are to be established at three key
stations (i.e., below Hoover, below Parker and at
Imperial Dams). The State of Nevada diverts Colo-
rado River main stem water from Lake Mead for use in
the Las Vegas area, and the returns enter the lake
just upstream from Hoover Dam. The gaging station
below Parker Dam is immediately downstream of the
major Lake Havasu diversion for the Metropolitan
Water District of Southern California. Also, the
Central Arizona Project now under construction will
divert from Lake Havasu, The large agricultural
areas in the Imperial and Coachella Valleys in
California and Yuma area in California are served
by diversions at Imperial Dam.

This action repeals the May 1976 adoption of the "Water Quality Stan-
dards for Salinity Including Numeric Criteria and Plan of Implementa-
tion for Salinity Control, Colorado River System", dated June 1975
and the "Supplement Including Modifications" to the above-referenced
document, August 26, 1975.

THE CODE OF COLORADO REGULATIONS

5 CCR 1002 - 10

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