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. . . . .5 hjgh as 10-11 millimhos within an 8 feet soil depth.. Sa\lnity is expected :0 be a problem, particularly in the western part 'of the Dolores Project ~tlined for irrigation. The Dolores River water at Dolores contains 1.00 to 300 ppm dissolved solids 90% of the time according to the U.S. G~logical Survey's Water Supply Papers. With additional soluble salt ~~cked up as the water flows in "the 42-mile Towaoc Canal, the irrigation water may be classified as a medium salinity hazard by the time it reaches the farm distribution systems, To reduce the salinity hazard such that the drainage water has a quality characterized by an electrical conductivity between. 5 and 10 millimhos needed by most of the crops in )0 _ :'_ - _'~ . the expected cropping pattern, a 4% to 8% leaching requirement must be aflowed. . A 5% allowance is made in\this analysis because leaching efficiency Under sprinkler irrigation is greater, relative to continuous flooding, which is a common practice in many areas that require periodic leaching. I 2.6 Net Irrigation Requirement ___The Technical Committee on Irrigation Water Requirements of the Irrigation and Drainage Division of the American Society of Civil Engineers recommends improvements in the procedure of estimating water requirements, involving proper component consideration (Jensen, 1973). The following analysis is based on the improved approach. The ne~ irrigation requirement per"unit area is the water that must be supplied"by irrigation to satisfy evapotranspiration, Et, leaching and miscellaneous water requirements that are not provided by precipitation, water stored in the soil, and precipitation that enters the soil. Precipitation on wet soil that results in drainage in excess of leaching . is not effective. The present procedure for estimating net irrigation requirement is given by: ":,:~ ; .>'