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

OTHER INDUSTRIAL USES

Coal gasification plants are being planned for
construction in New Mexico on the Navajo Indian
Reservation. Indications are that these plants will
require about 30,000 acre-feet of water a year, none of
which would be returned to the river system. Thus, as
with the thermal electric plants, even though dissolved
salts would be removed there would be some increase
in salinity downstream due to consumptive use of
water in the gasification plants.

The nation's increasing demand for oil has caused both
industry and Government to proceed with plans for the
mining of the tremendous oil shale reserves of the
Upper Colorado River Basin and the extraction of oil
from the shales. The final Environmental Impact
Statement on the Government's oil shale leasing
program was recently completed. The statement
recommends several measures that wou Id keep
dissolved salts in water used in the industry out of the_~
river system.

In the Lower Colorado River Basin, the San Diego Gas
and Electric Company has been working on plans to
construct a large nuclear powerplant in the Colorado
desert near Blythe, California, using the saline Palo
Verde Irrigation District drainwater for cooling tower
makeup and not returning the cooling tower blowdown
water to the Colorado River. The consumed drainwater
would be replaced by exchange with a water source
outside the Colorado Basin; thus, by consumptively
using a saline inflow to the river, this operation will
reduce both the total salt load in the Colorado River
downstream from the Palo Verde Irrigation District
drain and downstream salinity. The reductions will be
determined by the difference in salinity between the
drainwater, averaging about 1,800-1,900 ppm, and the
salinity of the river water, averaging about 750 ppm.

It is estimated that up to 60,000 acre-feet a year would
be used in this and similar operations by electrical
utilities in southern California.

REAPPRAISAL OF AUTHORIZED WATER
DEVELOPMENT PROJECTS

The Office of Management and Budget has directed
that a reappraisal be made by the Bureau of
Reclamation of presently authorized but
un constructed projects within the Upper Colorado
River Basin to identify the salinity impact of such
projects. In making this appraisal, the Bureau of
Reclamation will be changing some features of the
projects so that the salinity impacts of the projects will
be minimized. This may be accomplished by careful
analysis of lands to receive irrigation water to assure

that lands overlying saline formations will be excluded,
planning onfarm facilities to reduce excess applications
of water by farmers, changes in use of the project
water from irrigation to municipal and industrial uses
which are expected to add less salt to the system, and
other possible alternatives.

INSTALLATION OF TILE DRAINS

In order to combat the high salinity of Colorado River
water applied to their lands, farmers in the Imperial
and Coachella Valleys have installed thousands of miles
of tile drains at depths of 6 and 8 feet under their
fields to drain excess water and maintain ground-water
levels below the root zones. Through 1972, Imperial
Valley farmers installed 17 ,834 miles of tile drains at a
cost of $40.5 million, 1,848 miles of open drains at a
cost of $15.9 million, and the Imperial Irrigation
District provided master collection drains. A portion of
those collection ditches have been lined at a cost of
$10.3 million. The farmers are continuing to add more
tile drains at a rate of about 1,000 miles a year.
Coachella Valley farmers, irrigating about one-seventh
of the acreage of Imperial Valley farms, have installed
1,900 miles through 1972 at a comparable cost.

In addition to these substantial investments in facilities
to drain off the saline waters percolating through the
root zone, the tile drains require regular cleaning on an
interval of approximately 5 years, to remove salt
deposits and silt. Cleaning costs average about
$600/mile.

BLENDING OF COLORADO RIVER WATER
TO REDUCE SALINITY

The Metropolitan Water District of Southern California
imports over 1 million acre-feet a year of Colorado
River water into the Southern California coastal plain,
where over 10 million persons reside. Upon the 1972
completion of the first stage of the California State
Water Project, the District had available to it added
quantities of Northern California water with about
one-third the salinity of Colorado River water. In order
to reduce the salinity of the water delivered to its
service area, the District recently announced a program
involving significant expenditures which would allow
distribution of a 50-50 blend of the two waters to 75
percent of its service area.

PROJECTED SALINITY REDUCTION

Table 6 summarizes the salinity reductions that are
anticipated with implementation of the various
proposed salinity control measures outlined herein.

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