WSP00945

• File Number: 8442.400
• Description: Missouri Basin - Pick Sloan Project - Reports
• State: CO
• Basin: South Platte
• Water Division: 1
• Date: 2/28/1985
• Author: DoI, BoR
• Title: Lake Andes - Wagner Unit Planning Report / draft Enviromental Statement
• Water Supply Pro - Doc Type: Report/Study

Corn
Soybeans
Alfalfa

76%
12%
12%

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Armour station covered critical years and had very few periods of missing

record, it was selected for determining requirements for Lake Andes-Wagner

Unit. The CIa was calculated using historical recorded temperature and

precipitation data and calculated solar radiation for Armour, South Dakota.

The cropping pattern used was as follows:

This distribution was determined from agricultural economic analyses of the
area. It is the initial pattern expected upon completion of the project.
The computed annual average CIa for the above cropping pattern is 12.45
inches (1.04 feet), which is the design CIa used to determine the water
supply needed for the project.

Corn
Potatoes
Soybeans
Alfalfa

61%
15%
12%
12%

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A second cropping pattern which considers potatoes as a specialty crop is

typical of a development which is expected to occur in response to a

growing market. The cropping pattern was:

The average annual CIa for this cropping pattern is 11.57 inches (0.96 feet).
This is about 8 percent less than the design CIR, and would slightly reduce
future pumping costs.

Farm Delivery aequirement.--The farm delivery requirement is the amount of

water that is needed at the farm turnout. It includes the CIa plus onfarm

losses. The onfarm losses consist of spray and drift losses and deep per-

colation. The spray snd drift loss was assumed to be 15 percent and deep

percolat ion 10 percent of the farm delivery requirement. Thus the farm

delivery requirement is 12.45 inches per year plus 25 percent losses, or

16.60 inches.

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