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added to the compilation. copies of the NPDES permits listing are available to any individual or agency by contacting the Forum office. o ()1 -J I-" During the period of this report, the Executive Director with input from the Basin states has worked closely with EPA in the review and preparation of rules governing the treatment of Indian tribes as states under provisions of section 518 of the Clean Water Amendments of 1987. Specifically, the Forum's input has been in regard to standards, NPDES permits and sludge as those activities impact the most on the salinity of the Colorado River. OUTLOOK FOR MEETING STANDARDS IN THE FUTURE Flow-weighted average annual salinity concentrations for 1990 (provisional) were 145 mg/l below the numeric criteria at Hoover Dam, 118 mg/l below the criteria at Parker Dam, and 158 mg/l below the criteria at Imperial Dam. Based on the current level of salinity in the lower mainstem, the level of reservoir storage, the volume weighted salinity of the water in storage and the present level of water use in the Basin, it is clear that the criteria will not be exceeded during the next twelve-month period. The flow-weighted average annual salinity values (Calendar Year) at Hoover, Parker, and Imperial Dams during the period 1983 through 1987 decreased because of the record high runoff. During the period 1988 through 1991 below normal runoff has caused salinity concentrations to again increase. Implementation of Reclamation and Agriculture salinity control activities is continuing on the Grand Valley, uinta Basin, Paradox Valley, Dolores/McElmo Creek, Lower Gunnison Basin, and Big Sandy River Unit. However, it will be a number of years before significant effects are felt at the three lower mainstem stations. Although current salinity levels in the Colorado River System are below the criteria levels, studies by the Forum and Reclamation show that salinity concentrations will continue to increase over the long term. If planned salinity control measures as set forth in the 1990 Review are implemented, the man-caused increases in salinity can be held within the prescribed numeric criteria through the year 2010, based on average water supply conditions. While the levels of salinity concentrations will increase slowly, efforts to control salinity take many years to accomplish. Once completed, a salinity control project will take a number of years (4-5) for the full impact of the control measures to show results at Imperial Dam. Planning and implementation of the salinity control program also requires considerable time because of the many uncertainties associated with the complex and unique technologies required for salinity control. Therefore, it is imperative that the salinity control program as set forth in 1990 Review be carried out as scheduled. 18 ~"