WSP01636

• File Number: 8276.100
• Description: Grand Valley Unit - Colorado River Basin Salinity Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 10/1/1986
• Title: Summary Sheet -- Grand Valley Unit - Colorado River Basin Salinity Control Project
• Water Supply Pro - Doc Type: Project Overview

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SUMMARY SHEET
Grand Valley Unit
Colorado River Basin Salinity Control Project

October 1986
Page 1 of 2

LOCATION

The Grand Valley Unit, located in west-central
Colorado along the reach of the Colorado River
between the towns of Palisade and Mack. includes
Grand Junction. the largest city in western
Colorado. The hatched portion of the map shows the
Stage One area. The Stage Two area is the
remainder of the valley outside of the Stage One
area.

AUTHORITY

The Grand Valley Unit, a component of the Colorado
River Basin Salinity Control Project, was
authorized for construction by the Colorado River
Basin Salinity Control Act of 1974 (Public Law
93-320). Public Law 98-569, enacted in 1984,
amended title II provisions of that act.

PURPOSE

The purpose of the Grand Valley Unit is to reduce
the estimated 580,000 tons of salt added to the
Colorado River annually from the unit area as a
result of conveyance system seepage and
agricultural practices.

OVERALL PLAN

Studies for the overall unit have indicated that
the salt loading to the Colorado River in the Grand
Valley Occurs when conv~yance s~~.tem seepage and

irrigation return flows pass through highly saline
soils and the underlying Mancos Formation shale.
By reducing the amount of ground water percolating
through these saline sails, salt loading to the
Colorado River would be reduced, which in turn
would decrease the salinity of the river at
Imperial Dam, the last mcljor diversion point of the
Colorado River in the United States.

A conveyance systems improvement program is being
conducted by Reclamation as a cost-effective method
of reducing off-farm sl~epage and salt loading.
On-farm improvements, including upgrading
irrigation systems through cost assistance and
improving irrigation management to reduce deep
percolation from farm operations, are being studied
and implemented by the Soil Conservation Service.

STAGE ONE

Reclamation's program is being implemented in two
stages. After completion of prel iminary
environmental studies, a negative determination of
environmental impact was made in 1978. Preproject
hydrosalinity monitoring began in the Stage One
portion of the unit in 1976.

Stage One construction began in October 1980. The
Stage One area Covers approximately 10 percent of
the entire unit area and was designed to provide
information to fully analyze the effectiveness of
the overall unit. As part of the development, 6.8
miles of the Governmer\t Highline Canal were

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