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1 w 0) <D H::a /I i'}/j INTRODUCTION ' Salinity control work in the Colorado River Basin as been accomplished during the last decade by achieving , reater irrigation efficiency on irrigated cropland. 'R, geland watershed salinity control was deemed too expensive for the very large number of acres of rangeland within the river basin. The Soil Conservation Service (USDA, SCS, 1986) Sand Wash Watershed Rangeland Sediment and Salinity Control project is an example of cost effective rangeland salinity control at approximately $36.00 per ton. Salinity control planning and problem area identification on rangeland can be accomplished by modelling rangeland watersheds using a geomorphic-hydrologic unit model base in conjunction with resource targeting procedures. These types of studies have shown that a typical rangeland watershed will have approximately 7% to 15% of the' area in severely eroding condition. These severely eroding areas yield salts from soil and rock fragments carried as sediment in storm runoff and are responsible for approximately 75% to 90% of the accelerated or excessive sediment load being yielded to the Colorado River due to present or histori~ management practices. The Pacific Souhtwest Interagency Committee (PSIAC) 1968 Sediment Yield Procedure was used to document and quantify the sediment and salt related yields from the severely eroding areas. The salt yield was estimated as a percentage of the total sediment yield. The Colorado River Basin Rangeland Salinity Control Project was proposed by the SCS in a water quality issue paper (Raselyand Petersen, 1988) and implemented as ,a pilot study to test the resource modelling procedures and cost effectiveness of controlling salinity on rangeland watersheds (USDA, SCS, 1988). The project was organized with a primary interdisciplinary rangeland evaluation team consisting of a geologist-team leader (SCS), range conservationist (Bureau of Land Management-BLM) and a hydrologist (US Geological Survey-USGS). The team was augmented with specialists from BLM and SCS field offices , with responsibility for planning within the various targeted' '. , rangeland watersheds. The project was organized in two phases: Phase I - statewide watershed level targeting of the Colorado River Basin in Utah and Phase II - rangeland resource evaluation of eight targeted watersheds. The Phase I inventory was accomplished through the use of existing statewide resource maps on the scale of 1:500,000. The Phase II studies were accomplished by an augmented interdisciplinary team during a four week evaluation of each targeted watershed. '