WSP05534

• File Number: 8273.600
• Description: Colorado River Basin Salinity Control - Federal Agencies - USDA
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 4/1/1994
• Author: USDA
• Title: Monitoring and Evaluation Report for the McElmo Creek Unit of the Colorado River Basin Salinity Control Program - 1993 Annual Report
• Water Supply Pro - Doc Type: Annual Report

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3. Salinity in the McElmo Creek project Area

The geological formation of this area is the most important
factor that elevates the need for good irrigation water
management practices. Mancos Shale. formations underlay much
of the Montezuma Valley. This shale is of the marine origin
with a high salt content, which provides the main salt
source for the return flow into McElmo Creek. Excessive
irrigation and seepage from on-farm delivery systems.causes
deep percolation through the shale. The water dissolves
salt, which moves downward until it reaches a moderately
impermeable layer, then it moves laterally until it reaches
McElmo Creek, then the San Juan River, and finally the
Colorado River. (See Appendix A-2)

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4. Climatic conditions

The farms range in elevation from 5,800 to 7,000 ft. above
sea level. The temperature range is from 1000F to -20oF.
The annual precipitation is nearly 12 inches, including
snowfall. The last four years prior to 1992 were extremely
dry with yearly rainfall amounts around 5 to 7 inches.

Two weather stations are being used to collect the climatic
data for the project area. The south most station was used
for the 1993 monitoring season.

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S. Objectives of the MSE Program

The main obJectives of the M&E project for 1993 were:

1. To monitor and evaluate changes in salt loading entering
into the Colorado River system after the implementation
of improved irrigation systems on agricultural land
within the McElmo Creek Project Area.

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2. To monitor and evaluate changes in wildlife .habitat as a
.result of management changes in irrigation techniques,
farming procedures and the implementation of new
technology within the McElmo Creek Project Area.

3. To monitor and evaluate the on-farm economic impacts and
develop information that can be used by the cooperator
and the field office planning staff.

4. To have M&E personnel monitor only cooperators who are
presently or previously have been participants in the
Colorado'River Salinity Control Program.

This report addresses the M&E activities for the 1993
irrigation season.

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