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~ .... co W --.l has been viewed by some local entities as being In conflict w~h nutrient and toxlcs control and wildlife habitat Improvement ob- jectives. The seepage prevention strategy is being studied In the Pillman Verification Program. Once-through cooling water Is now diverted from unlined ditches into a pipeline. Several wells In the Pillman area are being used to monitor ground waler levels and quality. Ap- proximately 7.000 tons of salt have been reduced by the pipeline. A plan is being developed for a second program to test the developmenl of a ground water detention basin system. Each detenllon basin would be formed by a peripheral slurry trench/wall. If a detenllon basin system ap- pears feasible alter 2 years monitoring. additional large basins may be built. lower Gunnison Basin (USBR and USDA) The Lower Gunnison Basin Unit, In the Uncompahgre Valley In west-central Colorado, Is prin- cipally agricultural and agribusi- ness is of primary importance to the local economy. The recom- mended plan consists of eliminat- Ing winter water flows In the ir- rigation system. with replacement through the domestic water delivery system, concrete lining five separate Uncompahgre Project canal systems east of the Uncompahgre Riv", and Im- plementation of the L.:SDA on- farm program. The winter water replacement program would eliminate seepage from canals and laterals during the winler months and allow more efficient livestock watering. The program could reduce annual salt loading by about 80,000 tons. Advance plan- ning on the winter water replace- ment Is expected to be com- pleted in 1987. The advance planning on the canal and lateral lining will be conducted after more cost-effective measures have been impiemented. The USDA onfarm report out- lines an implementation plan that Is compatible with the Reclama- tion plan. Cost-effective areas have been Identified for high priority implementallon onfarm. In the North Fork area of the Lower Gunnison Basin, the primary causes of the salt load- Ing appear to be related to Irriga- tion delivery system seepage and applied Irrigation percolation through the saline soils. A sig- nificant amount of loading ap- pears to be contributed by natural sources due to the large drainage area and the extent to which It is underlain by Mancos Shale solis, abandoned gas, and oil exploration wells. Preliminary salinity control con- cepts to be considered include selectively lining canals and laterals and providing piped winter stock water rather than operating canals and laterals year-round. Other concepts will be considered as the investiga- tion proceeds. lower Virgin River (USBR) This study area is along the Lower Virgin River in north- eastern Clark County, Nevada, and northwestern Mohave Coun- ty, Arizona, and Includes natural saline ground water averaging 2.400 to 3.400 mg/L along the Vir- gin River between Riverside and Lake Mead. .' . In January 1984. Reclamation relnitlated the study to determine if a new water supply and salinity control project could be con- structed on the Virgin River. The project needs to locate up to 14,000 acre-feet of saline water that can be used as powerplant cooling water. The Plan Formula- tion Working Document is scheduled to be finalized in June t987. Mancos Valley (USDA) This un~ has met the prereq- uisite for construction and is awaiting funding. The report on this 9,200 acre Irrigated area along the Mancos River in south- western Colorado was completed In 1985. The recommended plan in- cludes 3,200 acres of sprinkler systems and other water manage- ment/salnity control treatment on about 5,500 total acres. About 17 miles of canal and lateral lining would combine many old earthen laterals. Total salt load reductions are estimated to be 8,800 tons per year. McElmo Creek/Dolores Project (USBR and USDA) Early study in the McElmo Creek Basin In southwestern Colorado show that salt loading results from both irrigation sour- ces and diffuse sources, with Ir- rigation being the main con- tributor. The recommended Reclama- tion plan to reduce salinity is to line three sections 01 Montezuma Valley Irrigation Company canals-- two on the Lone Pine Lateral and one on the Upper Hermana Lateral--and to inslalllalerals