7806

• UCREFRP Catalog Number: 7806
• Author: U.S. Department of the Interior.
• Title: Quality of Water, Colorado River Basin.
• USFW Year: 1997.
• USFW - Doc Type: Progress Report No. 18,
• Copyright Material: NO

Introduction

Water Quality

Although a number of water quality related legislative actions have been taken on the State and
Federal levels, four Federal acts are of special significance to the Colorado River Basin
(Basin)-the Water Quality Act of 1965 and related amendments, the Federal Water Pollution
Control Act Amendments of 1972 (Public Law 92-500), the Colorado River Basin Salinity Control
Act of 1974 as amended, and the Clean Water Act of 1977 as amended. Also central to water
quality issues are agreements with Mexico on Colorado River System waters entering that country.

The Water Quality Act of 1965 (Public Law 89-234) amended the Federal Water Pollution Control
Act and established a Federal Water Pollution Control Administration (now Environmental
Protection Agency [EPA]). Among other provisions, it required States to adopt water quality
criteria for interstate waters inside their boundaries. The seven Basin States initially developed
water quality standards that did not include numeric salinity criteria for the Colorado River
primarily because of technical constraints. In 1972, the Basin States agreed to a policy that called
for the maintenance of salinity concentrations in the Lower Colorado River System at or below
existing levels, while the Upper Basin States continued to develop their compact-apportioned
waters. The Basin States suggested that Reclamation should have primary responsibility for
investigating, planning, and implementing the proposed Salinity Control Program.

The enactment of the Federal Water Pollution Control Act Amendments of 1972 affected salinity
control in that the legislation was interpreted by EP A to require numerical standards for salinity in
the Colorado River. In response, the Basin States founded the Colorado River Basin Salinity
Control Forum (Forum) to develop water quality standards including numeric salinity criteria and a
basinwide plan of implementation for salinity control. The Basin States held public meetings on
the proposed standards as required by the enacting legislation. The Forum recommended that the
individual Basin States adopt the report, Water Quality Standards for Salinity Including Numeric
Criteria and Plan of Implementation for Salinity Control, Colorado River System. The proposed
water quality standard called for maintenance of flow-weighted average total dissolved solids
concentrations of 723 milligrams per liter (mg/L) below Hoover Dam, 747mgIL below Parker
Dam, and 879 mglL at Imperial Dam. Included. in the plan of implementation were four salinity
control units and possibly additional units, the application of effluent limitations, the use of saline
water whenever practicable, and future studies. The standards are to be reviewed at 3-year
intervals. All of the Basin States adopted the 1975 Forum recommended standards. EPA
approved the standards.

The Colorado River Basin Salinity Control Act of 1974 (Salinity Control Act) (Public
Law 93-320) provided the means to comply with United States' obligations to Mexico which
included, as a major feature, a desalting plant and brine discharge canal. These facilities will
enable the United States to deliver water to Mexico having an average salinity no greater than
115 parts per million (ppm) +/- 30 ppm (United States count) over the annual average salinity of
the Colorado River at Imperial Dam. The act also authorized construction of 4 salinity control
units and the expedited planning of 12 other salinity control projects above Imperial Dam as part
of the basinwide salinity control plan.

In 1978, the Forum reviewed the salinity standards and recommended continuing the construction
of units identified in the 1974 act, the placing of effluent limitations on industrial and municipal

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