WSP06497

• File Number: 8270.100
• Description: Colorado River Basin Water Quality/Salinity -- Misc Water Quality
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 1/1/1974
• Author: USDOI
• Title: Colorado River Water Quality Improvement Program - Status Report
• Water Supply Pro - Doc Type: Report/Study

increases would be in excess of $40 million a year by
the turn of the century.

QUALITY OF WATER-COLORADO
RIVER BASIN (USDI)

Biennial Progress Reports on the "Quality of
Water-Colorado River Basin" are prepared by the
Department of the Interior. The initial report was
issued in 1963 and the latest report is dated 1973. The
1973 report displays the past, present modified, and
estimated future quality of the Colorado River at 17
gaging stations for the period of 1941-1970. The future
quality condition as used in that report is an estimate
of the situation after the presently authorized
developments, projects proposed for authorization, and
private developments are placed in operation. The
re port estimates the present modified average
concentration below Hoover Dam to be 745 mg/I and
with future known developments, 971 mg/1. At
Imperial Dam the comparable estimates are 851 and
1,200 mg/l, respectively, under the same conditions.

COMPUTER SIMULATION OF THE HYDRO.
LOGIC SALINITY FLOW SYSTEM WITHIN
THE UPPER COLORADO RIVER
BASIN (USU)

Salinity conditions were investigated by Utah State
University. In 1970, the university issued a report
entitled "Computer Simulation of the
Hydrologic-Salinity Flow System Within the Upper
Colorado River Basin." This study employed an
electronic analog computer in developing a simulation
model of the hydrologic and salinity flow systems of
the Upper Colorado River Basin. Estimates were
derived based on the 1931-1960 period and reflect
cropping and riverflow regulation conditions as of
1960. The estimated salt load at Lees Ferry was 8.6
million tons per year of which approximately 4.3
million tons originated from natural sources, 1.5
million tons from within the agricultural system, and
2.8 million tons from other inputs to the system; thus,
natural sources are thought to contribute 50 percent of
the salt load, agricultural sources 17 percent, and
unidentified sources 33 percent. The report states that
the agricultural salt load and cropland consumptive use
increase the total dissolved solids concentration within
the Upper Basin by 104 and 113 mg/l, respectively.
The model was designed to predict the effects of
various possible water resource management
alternatives.

SALINITY OF SURFACE WATER IN THE
LOWER COLORADO RIVER-SALTON SEA
AREA (USGS)

U.S. Geological Survey Professional Paper No. 486-E,
entitled "Salinity of Surface Water in the Lower
Colorado River-Salton Sea Area," was published in
1971. The report shows that during the period
1926-1962, the chemical regimen of the Colorado
River at Grand Canyon and upstream, although
probably somewhat different from. the virgin regimen,
was relatively stable. There may, however, have been
small increases in average mineral concentrations,
particularly toward the end of the period, caused by
co~struction of reservoirs, increased irrigation, and
out-of-basin diversions. The research also found that
most of the mineral burden of the Colorado River, like
most of its flow, originates in the Upper Basin. The
largest individual increment to the mineral burden of
the Colorado River below the Lees Ferry compact
point and above Imperial Dam was found to be the
Blue Springs located near the mouth of the Little
Colorado River. The report further shows that a
principal increase in salinity in the lower reach is
derived from irrigated land in the Parker and Palo
Verde valleys.

~.I

THE MINERAL QUALITY PROBLEM IN THE
COLORADO RIVER BASIN (EPA)

In 1971, the EPA released its report entitled "The
Mineral Quality Problem in the Colorado River Basin."
In this report, salinity and streamflow data for the
1942-1961 period of record were used as a basis for
estimating average salinity concentrations under
various conditions of water development and use.
Under these conditions, concentrations at Hoover Dam
were estimated to average about 700 and 760 mg/l in
1960 and 1970, and 880 and 990 mg/I in 1980 and
2010, respectively. At Imperial Dam, the report
estimates 760 and 870 mg/I for 1960 and 1970, and
1,060 and 1,220 mg/l for 1980 and 2010 conditions.
The findings of the study with respect to salinity
sources were that natural sources accounted for 47
percent of the salinity concentrations at Hoover Dam.
The remainder was accounted for by irrigation (37
percent), reservoir evaporation (12 percent),
out-of-basin exports (3 percent), and M&I uses (1
percent) .

The present annual economic detriments of salinity
were estimated to total $16 million. The report further
advises that if no salinity controls are implemented, it

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