WSP04344

• File Number: 8282.600.10
• Description: Colorado River Operating Annual Reports
• Basin: Colorado Mainstem
• Date: 1/1/1987
• Author: USDOI/BOR
• Title: Operation of the Colorado River Basin 1987 Projected Operations 1988
• Water Supply Pro - Doc Type: Publication

Water Quality Operations

In recognizing the need to manage the water quality of the
Colorado River, it was recommended that long-term salinity
increases in the river be controlled through a water quality
improvement program as described in the report
"Colorado River Water Quality Improvement Program'
dated February 1972,

The program called for a basin-wide approach to salinity
control while the Upper Basin continues to develop its
compact-apportioned waters. The initial step toward
improvement of the future water quality in the basin was the
passage by Congress of the Colorado River Basin Salinity
Control Act of 1974 (Act) (Public Law 93-320) on June 24,
1974, authorizing the coostruction of various features for the
enhancement and protection of the quality of water available
in the Colorado River for use in the United States and
Mexico,

Title I of the Act enables the United States to comply with its
obligatioo under the agreement with Mexico of August 30,
1973 (Minute 242 of the International Boundary and Water
Commissioo, United States and Mexico), which was
concluded pursuant to the Treaty of February 3, 1944
(TS994). Title I authorized the construction of the Yuma
Desalting Plant and a bYl1ass drain to ultimately discharge the
plant's brine. These facilities, and others, will enable the
delivery of water at Morelos Dam, for subsequent use in
Mexico, having an average salinity no greater than 115 ppm
plus or minus 30 ppm (United States count) higher than the
annual average salinity of the Colorado .River water at
Imperial Dam,

Title II of the Act authorized the Secretary to construct a
number of units in the basin above Imperial Dam, as well as
the investigation of several other potential salinity control
units,

The Act, and its amendment by Public Law 98-569 of
October 30, 1985, directs the Secretary to submit a biennial
report to the President, the Coogress, and the Colorado River
Basin Salinity Control Advisory Council. Since the water
quality aspects of Colorado River operatioos are extensively
described in that biennial series, the latest of which is Report
No, 13 entitled, 'Quality of Water, Colorado River Basin;
dated January 1987, only minimal discussion of this aspect of
the operation below Imperial Dam is presented in this report.

During water year 1987, thc United States bypassed a (Otal of
125,000 acre-feet through the Bypass Drain. k the river was
in an excess flow condition during 1987 due to the high runoff
in the basin, no specific releases from the upstream reservoirs
were necessary to replace this water to meet the quantity
requirements of the Mexican Treaty of 1944,

During water year 1987, the average annual salinity of the
Colorado River water arriving at Imperial Dam was 595 parts
per million (ppm), During this same period, the salinity of the
waters arriving at Morelos Dam was 623 pprn, resulting in an
annual average salinity differential of only2S ppm, well within
the requirement of Minute 242 of the International Boundary
and Water Commission,

The total flows in the bypass drain during water year 1988 are
projected to be 125,000 acre-feel. A minor amount of
drainage water could be returned to the Colorado River
below Morelos Dam during 1988, Due (0 the excess flow
conditions that are expected, it will not be necessary to
provide replacement water to Mexico for the bypassed flows.

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