WSP04002

• 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

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is estimated that average annual economic detriments
would increase to $28 million in 1980 and $51 million
in 2010. More than 80 percent of these detriments
would be incurred by irrigated agriculture and the
associated regional economy located in the Lower
Basin and the southern California water service area.
The municipal detriments were based on the
calculation of additional soap and detergent
requirements, only.

The investigation examined three salinity control
alternatives: (1) augmentation of basin water supply,
(2) basinwide salt load reduction program, and (3)
limitation on further depletion of basin water supply.
The study concluded that the salt load reduction
program appeared to be the most feasible of the three
alternatives. It then proceeded to develop a broad
conceptual plan and related costs for such a program.

LOWER COLORADO REGION COMPRE-
HENSIVE FRAMEWORK STUDY (WRC)

The report by the Water Resources Council dated June
1971 states that high levels of dissolved mineral salts in
surface and ground waters are the major water quality
problem in the region. With few exceptions, most
surface. and ground-water supplies have mineral
concentrations exceeding 500 mg/I, and many exceed
1,000 mg/l. The salinity of the supplies affects
domestic, industrial, and agricultural uses.

The Colorado River enters the region at concentrations
exceeding 500 mg/l, varies between 500 and 900 mg/l
at most diversion points, and increases to as high as
1,000 to 1,150 mg/l for very short periods of time at
Imperial Dam. Salinity increases in the Colorado River
from Lees Ferry, Arizona, to Imperial Dam are due
principally to inputs from saline springs and the
concentrating effects of consumptive use and reservoir
evaporation.

Dissolved solids concentrations in the Colorado River
are estimated to increase about 55 to 75 percent
between 1965 and 2020, with the exception of
Imperial Dam where the concentration is estimated to
double. These results are based on the assumptions that
the Central Arizona Project is in operation and no
salinity controls are incorporated in future
de'velopments.

UPPER COLORADO REGION COMPRE-
HENSIVE FRAMEWORK STUDY (WRC)

The report by the Water Resources Council dated June
1971 states that salinity is the most serious water

quality problem in the Colorado River Basin.
Salt-loading and salt-concentrating effects of
consumptive use or depletion are the primary causes of
salinity increases. Salt loading principally results from
salts contributed from diffuse and point sources of
geologic origin and from salts carried in irrigation
return flows.

Future dissolved solids concentrations were estimated
for 1980, 2000, and 2020. The TDS concentration at
Lees Ferry, Arizona, assuming no salinity improvement
program, is projected at 820 mg/l for the year 2020, or
40 percent greater than the 1965 concentration. The
major cause of the projected salinity increase is
continued development of the region. It includes the
additional stream depletions for irrigation, thermal
power production and export, and the additional salt
leached from newly irrigated lands.

State and Federal representatives in both the upper and
lower Colorado regions agreed that the salinity
improvement programs outlined in the Upper and
Lower Colorado Framework Study documents should
be part of a basinwide approach to salinity
management. The salinity improvement program
consists of a salt-loading reduction program which
maintains concentrations at Lees Ferry at about 600
mg/l through the year 2020.

THE EPA ENFORCEMENT CONFERENCE

The Seventh Session of the Conference in the Matter of
Pollution of the Interstate Waters of the Colorado
River dealt primarily with the salinity issue, The
conference was held under the provisions of Section 10
of the Federal Water Pollution Control Act which
authorized the EPA Administrator to initiate such a
conference when reports or studies show that pollution
subject to abatement under the Federal Act is
occurring. In this case, the previously described 1971
report by the EPA on "The Mineral Quality Problem in
the Colorado River Basin" was used as the backup
study, The Conference was held on February 15,17,
1972 and was continued and concluded on April
26-27,1972.

Conclusions and recommendatons of the enforcement
conference were reached unanimously by conferees
representing the seven Basin States and the Federal
Government. They were:

"I. It is recommended that: A salinity policy be
adopted for the Colorado River System that would
have as its objective the maintenance of sal inity

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