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Water Quality Operations Beach end sun enthusIasts. In recognizing the need to manage the water quality of the Colorado River, it was recommended that long-term salinity increases in the river be controlled through a water quality improvement program as described in the report "Colorado River Quality Improvement Program" dated February 1972. The program called for a basin-wide approach to salinity control while the Upper Basin continues to develop its compact- apportioned waters. The initial step toward improvement of the future water quality in the basin was the passage by Congress of the Colorado River Basin Salinity.Control Act on 974- (Aclnpublic Law 93.320) on June 24, 1974. authorizing the construction of various features for the enhancement and protection of the quality of water available in the Colorado River for use in the United States and the Republic of Mexico. Title I of the Act enables the United States to comply with its obligation under the agreement with Mexico of August 30, 1973 (Minute 242 of the International Boundary and Water Commission, United States and Mexico). which was concluded pursuant to the Treaty of February 3. 1944 (TS994). Title I authorized the construction of the Yuma Desalting Plant and a bypass drain to ultimately discharge the plant's brine. 26 Sorghum inspection lor effects due 10 solly soils. These facilities, and others, will enable the delivery of water at Morelos Dam, for subsequent use in Mexico, having an average salinity no greater than 115 ppm :t. 30 ppm (United States count) higher than the annual overage salinity of the Colorado River water at Imperial Dam. Title II of the Act authorized the Secretary of the Interior to con",truct a number 0'1 units in the basin above Imperial Dam, as well as the investigation of several other potential salinity control units. The Act, and its amendment by Public law 98.56.9 of Qqol1e.!. 30. 198<1. directs the SeCretary of the Interior to submit a biennial report to the President, the Congress, and the Colorado River Basin Salinity Control Advisory Council. Since the water quality aspects oi Colorado River operations are extensively described in that biennial series, the latest of which is Report No. 12 entitled," Quality of Water, Colorado River Basin," doted January 1985, only minimal discussion of this aspect of the operation be!ow Imperial Dam is presented in this report. During water year 1984, the United States bypassed a total of 137,500 acre.feet through the Bypass Drain and MODE 3. ~ '" Woler - iust one of our valuable resources. As the river was in an excess flow condition during 1984 due to the extremely high runoff in the basin, no specific releases from the upstream reservoirs were necessary to replace this water to meet the quantity requirements of the Mexican Treoty of 1944. Du ri ng water year 1984, the average annual salinity 0'1 the Colorado River water arriving at Imperial Dam was 688 ppm. During this same period, the salinity of the waters arriving at Morelos Dam was 697 ppm, resulting in an annual average salinity differential of only 9 ppm, well wi!hLn the_ r~quJr:.el1}e!Jt_otMi(\ute 242.of the International Boundary and Water Commission. The total flows in the bypass drain during water year 1985 are projected to be 150,(X)() acre.feet. A minor amount of drainage water could be returned to the Colorado River below Morelos Dam during 1985. Due to the excess flow conditions that are expected, it will not be necessary to provide replacement water to Mexico for the bypassed flows.