WSP07690

• File Number: 8277.600.10
• Description: Big Sandy River Unit - Colorado River Salinity Control Program
• State: WY
• Basin: Colorado Mainstem
• Date: 9/1/1987
• Title: Final Environmental Impact Statement for the Big Sandy River Unit
• Water Supply Pro - Doc Type: EIS

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COLORADO RIVEll
SALINITY CONTlIOI, PllOGRAM
FINAL ENVIRONMENTAL IMPACT STATEMENT

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BIG SANDY RIVER UNIT
SUBLETTE AND SWEETWATER COUNTIES, WYOMING

Lead Agency

Soil Conservation Service, USDA

Cooperating Agencies

Agricultural Stabilization and Conservation Service, USDA
Cooperative Extension Service, USDA
State of Wyoming
State Engineer's Office
Department of Environmental Quality
Wyoming Came and Fish Department
Department of Agriculture

PREPARED BY

UNITED STATES DEPARTMENT OF AGRICULTURE
SOIL CONSERVATION SERVICE
CASPER, WYOMING

September 1987

Abstract

Voluntary implementation by individual landowners of the Selected Plan (low-pressure
sprinkler irrigation with individual onfarm pumping) on 15,700 acres will increase the
present average onfanm effici~ncy from 39 percent to 68 percent and average project
efficiency from 32 percent to 50 percent. The change in onfarm efficiency will result in
less deep percolation from the fanm area and resulting return flow from the saline seeps
along the Big Sandy River. This will result in a reduction of 52,900 tons of salt
annually entering the river system. This reduction will translate to a decrease in
salinity concentration in the Creen River at the town of Creen River, Wyoming, of
27 milligrams per liter and a decrease of 5 milligrams per liter at Imperial Dam on the
lower Colorado River.

If voluntary pr09ram participation occurred on 15,700 acres of the 18,370 eligible
cropland acres, about 3,775 acres of irrigation-induced and supplemented wetlands (USFWS
Circular 39 types 1, 2, 3, 4, 9, and 10) will be adversely affected. Of this total,
1,010 acres will experience reduced water supply and an estimated 2,765 acres will be
eliminated. The majority of these wetland acres are classified as types 1 and 2 wetlands.
Wildlife habitat values foregone will be replaced through voluntary cost-shared assistance
for the development and enhancement of wetlands and adjacent upland vegetation. Various
salinity control and conservation practices will be installed or implemented to create and
enhance wildlife habitat (vegetation) around ponds, ditches, wetlands, field edges, and
odd areas.

Questions on this Environmental Impact Statement should be directed to Frank S. Dickson,
State Conservationist, Soil Conservation Service, Room 3124, Federal Building, 100 East B
5treet, Casper, Wyoming 82601. The telephone numbers are [phone] or FT5 328-5201.

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