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<br />l\) <br />00 <br />CJ1. <br />c.o <br /> <br />directly related to the water supply, the amount of reservoir storage, <br />and the rate of water use. For example, with a long-term average <br />virgin flow at Lee Ferry of 15 maf/yr and a moderate water use rate, <br />the 1990 salinity at Imperial Dam in the absence of any salinity <br />control measures would be 995 mg/l. <br /> <br />Reduction in Projected Salinity Required to Maintain 1972 Levels <br />The policy set forth in the EPA regulation [40 eFR Part 120, <br />Water Quality Standards], published on December 18,1974, calls for <br />maintenance of salinity in the lower main stem of the river at or <br />below the average value found during 1972 while the Basin States <br />continue to develop their compact-apportioned waters. The 1972 <br />average value is understood to be the flow-weighted average. If the <br />1972 levels are to be maintained, salinity control measures must be <br />undertaken. <br /> <br />The projected salinities, both with and without salinity control <br /> <br /> <br />measures, assuming no increase in water supply, are presented in <br /> <br /> <br />Tables 4, 5, and 6 for Hoover, Parker and Imperial Dams. The water <br /> <br /> <br />supply and depletion rate assumptions were described earlier. Salinity <br /> <br /> <br />control measures consist of a number of federal and nonfederal actions. <br /> <br />These are described in detail in subsequent chapters. <br /> <br /> <br />Using the salt routing model, analyses were made to determine <br /> <br /> <br />the impact on salinity i~ the lower main stem for the full range <br /> <br /> <br />of water supply and depletion rates combined with full implementation <br /> <br /> <br />of salinity control measures. These measures include no salt return <br /> <br />for electrical generating station cooling, the coal gasification and <br />coal development industries and the oil shale industry; reformulation <br /> <br />-29- <br /> <br />J. <br />