WSP10235

• File Number: 8281.910
• Description: Colorado River Studies and Investigations -- Grand Valley Salinity Study
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 12/1/1976
• Author: Soil Cons Serv
• Title: Grand Valley Salinity Study - draft
• Water Supply Pro - Doc Type: Report/Study

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Four irrigation entities divert water from the Colorado River. These

Include the Grand Valley Water Users Association (Bureau of Reclamation

Project), Grand Valley Irrigation Company, Palisade Irrigation District,
and Mesa County Irrigation District. A fifth irrigation company, the

Redlands Power.and Water Company, diverts water from the Gunnison River.

A ~umber of other small companies have carriage agreements with the

major canal companies for delivery of water.

First irrigation in the valley began in 1882 with the construction

of what is now the Grand Valley Canal (~rand Valley Irrigation Company).
Other private systems were built during the period between 1882 and 1908.

Construction of the last major system, the Grand Valley Project under

the Reclamation Service, began in 1908 with the major construction

completed in 1926. This project consists of two divisions, t.he Garfield

Gravity and the Orchard Mesa Divisions, on the north and south sides of

the river, respectively.

The soils of this general area are derived from the Mancos Shale

formation. This marine formation has a very high salt content and

ground water percolating over and through the shale picks up high concen-

trations of salt which are transported to the Colorado River through

wasteways, ditches, or by natural ground water movement to the river.

Because of the arid climate, these salts have not been leached naturally,

and high quantities remain. Lenses of white crystalline salts are often

exposed during excavation operations. The Mancos formation consists of

3,000 to 5,000 feet of relatively uniform silty clay shale with veinlets

of gypsum, calcite, and sodium sulphate.

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