WSP11664

• File Number: 8220.128.J
• Description: Silt Project
• State: CO
• Basin: Colorado Mainstem
• Water Division: 5
• Date: 8/1/1961
• Title: Report of the Reappraisal of Direct Agricultural Benefits and Project Impacts - Silt Project-Colorado - Part 1 of 2
• Water Supply Pro - Doc Type: Report/Study

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were furnished by the Agricultural Research Service
Soil Survey Laboratories in Fort Collins, Colorado.
field sheets and laboratory data were obtained from
mati on.

and the Cooperative
Land classification
the Bureau of Rec1a-

Evaluation area A comprises 3,218 acres of which 71 percent are in capa-
bility class III and 29 percent in capability class II. The 1,462 acres
in evaluation area B, 215 acres in evaluation area D, 177 acres in evalu-
ation area F and the 346 acres in evaluation area H are all in capability
class IV. Evaluation area C comprises 657 acres of which 62 percent are
in capability class II and 38 percent in capability class III. Eighty-
eight percent of the 181 acres in evaluation area E are in capability class
III and 12 percent in capability class II. Evaluation area G comprises 341
acres of which 84 percent are in capability class III and 16 percent in
capability class II.

It is concluded that soils comprising the 6,597 acres of land designated
by the Bureau of Reclamation as the Silt Project, which have been inter-
pretively grouped into capability classes 11-1,400 acres, 111-2,997 acres,
and IV-2,2oo acres, are suitable for cultivation under irrigation.

Irrigation Supplies and Requirements

Several studies of irrigation r~qu!rements have been made in the general
viclnityof the Silt project. These data, with additional information
supplied by personnel familiar with the area, were used in estimating
irrigation water requirements. In the past the water supply has averaged
about one-third of requirements in the Dry Elk Valley and about two-thirds
of requirements on Harvey Mesa. Estimated water requirement at the farm
headgate is 2.86 acre-feet per acre. Weighted future average on-farm
irrigation efficiencies are estimated at 53 percent and weighted average
net seasonal crop consumptive use at 18.2 inches.

The period 1937-60 was selected as the basis for project water supply studies.
Project water supplies during a period of years of comparable precipitation
and water yield would with project average 2.74 acre-feet per acre of irri-
gation water at the farm headgate, thus meeting 96 percent of the average
water requirements of the project lands.

Land and Irrigation Development

Estimates of development costs for project lands were made by evaluation
areas on the basis of the level of management expected on the project and
the pnysica1 requirements of the soils and site conditions. They are con-
sistent with anticipated irrigation efficiencies and expected crop yields.

Estimated costs include land leveling and the establishment of farm irri-
gation systems and associated requirements. Estimated on-farm drainage
costs for a limited acreage of project lands with water table conditions
are also included.

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