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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SUMMARY

This report contains the results of evaluations by the Soil Conservation

Serv i ce on 4,620 acres (} percent samp I e) of i rr i gated crop I and in the

west end of Grand Valley, and the extrapolation of these results over

the entire valley. Present irrigation practices were evaluated to

establish existing conditions as a basis for recommending on-farm

improvements and to measure effects of the improvements.

Four program alternatives were evaluated. Alternative one considered an

improvement in irrigation management by changing the time of set and

some system improvements; the second considered more extensive improve-

ments in existing systems and management of the time of set and flow

rates; the third, the same as alternative 2, considered changing 5,000

acres to drip or sprinkler methods of irrigation and management practices

including cut-back flow rates; and the fourth program alternative level

of on-farm irrigation improvement is a combination of the other alternatives.

The annual salt load pickup attributed to on-farm irrigation is estimated

to be 360,000 tons while upland erosion contributes another 80,000 tons

accounting for 440,000 tons of the annual salt load increase from Grand

Valley in the Colorado River. The Bureau of Reclamation has estimated

an additional 350,000 tons'per year of salt pickup due to seepage from

off-farm canals and laterals in the valley.

The program alternatives contained in this draft report have not yet

been discussed with the local people so they can indicate a preference.

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