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General Description| Plan| Development| Benefits


General Description

The Colorado River and its tributaries provide municipal and industrial water for more than 23 million people in the seven Basin States and irrigation water to nearly 4 million acres of land. The threat of salinity is a major concern in both the United States and the Republic of Mexico. Salinity affects agricultural, municipal, and industrial users. Damages in Mexico are unquantified, but damages in the United States typically range between $500 million and $750 million per year.

Reclamation is working with the U.S. Department of Agriculture and the Bureau of Land Management in the Colorado River Basin Salinity Control Program to build many salinity control projects on the Colorado River. The program's overall goal is to cost-effectively reduce the amount of salinity in the river water.

High salinity levels make it difficult to grow winter vegetables and popular fruits. Salt in water systems plugs and destroys municipal and household pipes and fixtures. Studies show that salinity damages in the United States` portion of the Colorado River Basin range between $500 million and $750 million per year and could exceed $1.5 billion per year if future increases are not controlled. Damages in the Republic of Mexico have not been quantified, but may be expected to exceed $100 million per year.Graphic

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The 1974 Colorado River Basin Salinity Control Act, Public Law 93-320, authorized the construction, operation, and maintenance of works in the Colorado River Basin to control the salinity of water delivered to Mexico.

Facility Descriptions

Title I

Title I of the Act provided the means to comply with the obligations made by the United States to Mexico in Minute No. 242 of the International Boundary and Water Commission, United States and Mexico. This minute, formally approved by the United States and Mexico on August 30, 1973, is an agreement by the two governments. It provides that the United States shall adopt measures to ensure that 1.36 million acre-feet of water delivered annually to Mexico upstream of Morelos Dam shall have an average salinity of no more than 115 +30 parts per million over the annual average salinity of Colorado River water arriving at Imperial Dam. The agreement further provides for the United States to deliver to Mexico, across the land boundary at San Luis, Arizona., and in the Limitrophe Section of the Colorado River downstream from Morelos Dam, approximately 140,000 acre-feet of water annually, with salinity substantially the same as that of water customarily delivered there. The minute also provided that the concrete-lined Main Outlet Drain Extension (MODE) be extended from Morelos Dam to the Cienaga de Santa Clara in Mexico at United States expense. Features authorized under Title I of the 1974 Salinity Control Act are:

Yuma Desalting Plant

The desalting plant is located on a 60- acre tract of land located approximately 6 miles west of Yuma, Arizona is designed to improved the quality of irrigation drainage water from the Wellton Mohawk Irrigation and Drainage District (WMIDD) so that it can be returned to the Colorado River and delivered to Mexico in partial satisfaction of the Mexican water Treaty of 1944. The Yuma Desalting Plant is a membrane-process desalting plant, a pretreatment plant, and the necessary appurtenant works to treat drainage water from the Wellton Mohawk Division, Gila Project .

Coachella Canal Unit

This unit is involved in replacing the first 49 miles of the existing unlined Coachella Canal with a new concrete-lined canal. This action will save most of the water that is being lost through seepage in the unlined reach of the canal.

Protective and Regulatory Pumping Unit

This unit will provide for construction of a well field located on a 5-mile-wide strip of land along the Southerly International Boundary between Arizona and Sonora, Mexico. Minute No. 242 limits the quantity of water pumped from the combination of private wells and the unit well field to 160,000 acre-feet annually. A significant amount of the water pumped by the unit will be delivered the Southerly International Boundary near San Luis, Ariz. This water , when combined with the drainage and regulatory waste flows from the Valley Division of the Yuma Project, will make up the 140,000 acre-feet per year of water delivered to Mexico at the Southerly International Boundary. This 140,000 acre-feet of water, with 1,360,000 acre-feet of water delivered and the Northerly International Boundary, will make up the 1,500,000 acre-feet of Mexican Treaty entitlement to Colorado River water.

Reject Stream Replacement Study

In connection with the desalting plant, but to be investigated independently, Section 101 c of the act authorized the Reject Stream Replacement Study to identify feasible measure which could adequately replace the water lost through reject from the Yuma Desalting Plant and any Wellton Mohawk drainage water bypassed to the Santa Clara Slough. The source of any such replacement water was limited by the act to the States of Arizona, Colorado, California, New Mexico, and those portion of Nevada, Utah, and Wyoming which are within the natural drainage basin of the Colorado River. The investigation on replacing the reject stream from the Yuma Desalting Plant is continuing. Studies are presently on going with the focus on two primary alternatives. (a) off stream banking of surplus Colorado River water to be used later to offset the reject stream, and (b) increasing return flow credits in the Yuma area and using part of that credit to offset the reject stream.

Title II

Title II of the Salinity Control Act authorized several specific salinity control units upstream from Imperial Dam to meet the objectives and standards set by the Clean Water Act. The cost effective portions of these units have all been completed. Title II projects that were implemented:

Grand Valley Unit in Mesa County, Colorado
Las Vegas Wash Unit in Clark County, Nevada
Lower Gunnison Basin Unit in Delta and Montrose County Colorado.
McElmo Creek Unit -- Dolores Project in San Juan and Montezuma Counties of Utah and Colorado
Meeker Dome Unit in Rio Bianco County, Colorado
Paradox Valley Unit in Montrose County, Colorado
Price-San Rafael Unit in Emery, Carbon, Wayne, and Garfield Counties, Utah
San Juan River Unit in San Juan County, New Mexico

Title II Projects to be implemented after new/revised investigations:

Mancos Valley Unit, Montezuma County, Colorado

Title II projects investigated but determined not to be cost-effective:

Big Sandy River Unit in Sublette and Sweetwater Counties, Wyoming
Blue Springs Unit in the Navajo Hopi Indian Reservation, Arizona
Colorado River Indian Reservation Unit in La Paz County, Arizona, and the eastern part of San Bernardino and Riverside Counties, California
Dirty Devil River Unit in Emery and Wayne Counties, Utah
Glenwood-Dotsero Springs Unit in in Eagle, Garfield, and Mesa Counties
LaVerkin Springs Unit in Washington County, Utah
Lower Virgin River Unit in Clark and Mohave Counties of Nevada and Arizona
Palo Verde Irrigation District in Riverside County, California
Sinbad Valley Unit in Montrose and Mesa Counties, Colorado
Uinta Basin Unit in Duchesne and Uintah Counties, Utah.
Bureau of Land Management

In 1994, Public Law 98-569 amended the Colorado River Basin Salinity Control Act and directed the Secretary to develop a comprehensive program for minimizing salt contributions from lands administered by the Bureau of Land Management (BLM) and to provide a report on this program to the Congress and the Advisory Council. BLM's program is designed to provide the best management of the basic resource base. Successes with the resource base will translate to improved vegetation cover, better use of onsite precipitation, and stronger plant root systems. In turn, a more stable runoff regime and reduced soil loss should result; thus, benefitting water quality of the Colorado River.

The1987 Report, Salinity Control on BLM-Administered Public Lands in the Colorado River Basin outlines BLM`s implementation actions; and quantifies, classifies, and maps the saline soils on lands administered by BLM.

U.S. Department of Agriculture

Public Law 98569 provides a separate authority for implementing U.S. Department of Agriculture (USDA) Colorado River Salinity Control projects. The initial funds for implementation were appropriated in 1987. Public Law 98569 authorized the Secretary of Agriculture to

1. Identify salt source areas and develop project plans for salinity control

2. Provide financial and technical assistance to land users to plan, install, and maintain salinity reduction practices including voluntary replacement of incidental fish and wildlife values foregone

3. Conduct research, demonstration, and education activities

4. Monitor and evaluate program effectiveness

Basinwide Salinity Control Program

In 1995, Public Law 104-20 authorized an entirely new way of implementing salinity control. Reclamation`s Basinwide Salinity Control Program opens the program to competition through a `Request for Proposal` process which has greatly reduced the cost of salinity control. The average cost of salinity control measures has dropped from about $70 per ton to $30 per ton. P.L.104-20 directed Reclamation to conduct a $75 million test of a pilot program to award grants on a competitive-bid basis for salinity control projects. This program has helped 24 projects totaling $109 million?yet the same projects under the old program would have cost over $300 million. New salinity control projects are funded by a one-time grant that is limited to the sponsor`s competitive bid. Once constructed, the facilities are owned, operated, maintained, and replaced by the sponsors at their own expense.

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Increases in the salinity levels of western rivers is not a new or unique situation. Water quality problems in the Colorado River were recognized as early as 1903. The Colorado River salinity problem has been the object of several studies and investigations, and numerous surveys of salinity sources and control measures have been pursued over the years by Reclamation, U.S. Geological Survey, Environmental Protection Agency, Water Resources Council, Colorado River Board of California, Basin States, and several universities.

In the 1960`s and early 1970`s, the seven Colorado River Basin states and federal representatives discussed the problem of increasing salinity levels in the lower reaches of the Colorado River. In 1972, Congress enacted the Clean Water Act, which mandated efforts to maintain water quality standards in the United States. At the same time, Mexico and the United States were discussing the increasing salinity of Colorado River water being delivered to Mexico.

In 1972, a joint Federal-State enforcement conference on the subject of pollution of interstate waters of the Colorado River and its tributaries initiated formal efforts to establish an overall salinity control policy. Conferees concluded that such a policy would have as its objective, `the maintenance of salinity concentrations at or below levels found in the lower main stem of the Colorado River in 1972.` It also was recognized that States had rights to continue development of their compact-apportioned waters and that temporary rises in salinity might occur until the salinity control program became effective.

In 1973, the Basin states established the Colorado River Basin Salinity Control Forum for interstate cooperation and to provide the information needed to comply with Section 303(a) and (b) of the Clean Water Act. Governors from each of the seven Basin states appoint representatives to the Forum.

The EPA's December 1974 regulations set forth a basinwide salinity control policy for the Colorado River Basin. The Basin states, acting through the Forum, initially responded to this regulation by developing and submitting to the EPA a June 1975 report, Water Quality Standards for Salinity Including Numeric Criteria and Plan of Implementation for Salinity Control - Colorado River System.

Since the states` initial adoption, the water quality standards have been reviewed every three years (1978, 1981, 1984, 1987, 1990, 1993, 1996, and 1999) as required by Section 303(c)(1) of the Clean Water Act.


The standards require that a plan be developed which will maintain the flow-weighted average annual salinity at or below the 1972 levels while the Basin states continue to develop their compact-apportioned water supply. The Forum selected three stations on the mainstem of the lower Colorado River to measure the salinity of the Colorado River:

1. Below Hoover Dam

2. Below Parker Dam

3. At Imperial Dam

Numeric criteria were established for these points as required by the 1974 regulation. The Forum and participating federal agencies developed an implementation plan as part of the standards. It was designed to ensure compliance with the numeric criteria for salinity. Every three years, the numeric criteria are reviewed and the implementation plan is updated to ensure continuing ompliance with the standards.


Congress enacted the Colorado River Basin Salinity Control Act (P.L. 93-320) in June of 1974 with the Forum`s support. Title I of the Act addresses the United States` commitment to Mexico and provided the means for the United States to comply with the provisions of Minute No. 242. Title II of the Act created a water quality program for salinity control in the United States. The Secretary of the Interior was primarily responsibile for the federal program. Reclamation was instructed to investigate and build several salinity control units. The Secretary of Agriculture was instructed to support the effort within existing authorities.

The Public Works Appropriation Act of 1975 provided funding for the start of advance planning activities on the four authorized units. Title II provided for feasibility investigations and planning and implementing the other units.

The Colorado River Basin Salinity Control Act was amended in 1984 by P.L. 98-569 to authorize two additional units for construction by Reclamation. The amendments directed the Secretary of the Interior and the Secretary of Agriculture to give preference to the salinity control units with the least cost per unit of salinity reduction. The Act was also amended to establish a voluntary on-farm salinity control program to be implemented by the Department of Agriculture and provided for voluntary replacement of incidental fish and wildlife values foregone on account of the on-farm measures. Many cost-effective salt-load reducing activities were accomplished in the decade following that authorization. P.L. 98-569 also directed the Bureau of Land Management (BLM) to implement salinity controls.

Reclamation and the Forum in 1994 concluded that the existing Act, as amended, with its unit-specific approach and authorization ceiling, was limiting salinity control opportunities. In 1995, the Act was amended by P.L. 104-20 to authorize an entirely new way of implementing salinity control. Reclamation`s new Basinwide Salinity Control Program opens the program to competition through a public process and has greatly reduced the cost of salinity control. An additional $75 million of expenditures by Reclamation were authorized by P.L. 104-20.

The Federal Agriculture Improvement and Reform Act (FAIRA) of 1996 (P.L. 104-127) further amended the U.S. Department of Agriculture`s (USDA) role in salinity control by creating a new conservation program known as the Environmental Quality Incentives Program (EQIP) which combined four conservation programs including USDA`s Colorado River Salinity Control Program. FAIRA, provided authority for funding the nationwide EQIP through the year 2002. USDA has created rules and regulations concerning how EQIP funds are to be allocated. The past authority for the states to cost-share from the Basin funds was retained in the new EQIP program with links to Reclamation`s authority to distribute Basin funds for cost-sharing.


The Paradox Valley, Grand Valley, and Las Vegas Wash Units were authorized for construction by Title II of Public Law 93-320. Major structural features of these units, with the exception of Crystal Geyser, involve construction of facilities such as wells, dikes, pipelines, pumps, desalters, and evaporation ponds to collect and dispose of saline water.

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The beneficial impacts of salinity reduction will be reflected in all the Basin States in improved water quality deliveries to over 23 million people and nearly 4 million acres of irrigated farmland. Using a relatively conservative analysis, the benefit of salinity control was estimated to be $340 per ton (1994 dollar values). In comparison, the cost of salinity control generally ranges from $20 to $100 per ton.

Figure 1-1 displays a cumulative estimation of the amount of salt the Colorado River Basin Salinity Control Program has removed.Graphic

In 1997, the salinity at Imperial Dam was 713 mg/L. At this level of salinity, damages exceed $500 million per year. As salinity approaches the salinity standards levels (879 mg/L at Imperial Dam), damages are projected to increase to about $1 billion per year. Without further salinity controls to offset development, damages will increase another quarter of a billion dollars per year.

Last updated: Apr 18, 2011