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<br />SUMMARY
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<br />The Selected Plan propoaes the installation of the following atructures
<br />on 15,700 acres of irrigated land in the Big Sandy River Unit to reduce
<br />salinity in the Colorado River Basin. (See Figure S-l, Location Map.)
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<br />Distribution Pipeline and Risers
<br />Motor, Pumps, and Valves
<br />Low Pressure Sprinkler Irrigation Systems
<br />Semi-Automated and Automated Border Irrigation Systems
<br />Irrigation-Regulating Reservoirs and Wasteway System
<br />Voluntary Replacement of Fish and Wildlife Habitat Values
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<br />Economic and environmental analyses are based on the estimated
<br />15,700 acres of participation. Actual acreage will vary depending on
<br />individual participation in the program. Participation will be
<br />voluntary and implemented through long-term contracts administered by
<br />the ASCS. Technical assiatance for salinity control and conservation
<br />planning, implementation of planned practices, assistance to realize
<br />irrigation water management objectives, and installation of fish and
<br />wildlife practices will be provided by the SCS. An SCS project team
<br />will consist of soil conservationists, an irrigation water management
<br />specialist, engineers, a biologist, civil engineering technicians, and
<br />soil conservation technicians. Additional technical assistance will be
<br />provided by the CES.
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<br />Implementation of the Selected Plan will result in a reduction of an
<br />estimated 52,900 tons of salt annually entering the Big Sandy River.
<br />This will decrease salinity concentration in the Green River at the town
<br />of Green River, Wyoming, by 27 milligrams per liter and decrease
<br />salinity concentration by 5 milligrams per liter at Imperial Dam on the
<br />lower Colorado River.
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<br />The Selected Plan will also increase hay production by an average yield
<br />of more than 2 tons annually. Present average yields of hay vary from
<br />1.6 tons/acre to more than 4 tons/acre. In addition to the increased
<br />yields, irrigators will be able to maintain pure stands of alfalfa or
<br />higher-value crops. These benefits will include: stands maturing
<br />earlier, remaining productive longer, and may produce an additional
<br />cutting ,yearly.
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<br />If 15,700 acres were converted to sprinkler and other improved
<br />irrigation systems, about 3,775 acres of irrigation water induced and
<br />supplemented wetlands (USFWS Circ. 39, Types I, 2, 3, 4, 9, and 10) will
<br />be affected. See Glossary for definition of wetland types. Typical
<br />wetlands in the project area are shown in Figures 2-5 and 2-6 in
<br />Chapter 2. Reduced water supply will occur on about 1,010 acres of
<br />wetlands, and 2,765 acres of wetlands will be eliminated. The majority
<br />of the 3,775 acres of wetlands are Types I, 2, and 9. To replace
<br />wildlife habitat values foregone, the habitat quality of about 860 acres
<br />of Types 3, 4, and 10 wetlands will be voluntarily preserved and
<br />enhanced by pond lining, livestock exclusion, seeding, and installation
<br />of nesting islands. Landowners. the Irrigation and Drainage District,
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