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<br />STORAGE CHANGES <br /> <br />o <br />Ul <br />CO <br />tv <br /> <br />Upper and Lower Basin reservoir storage increased from 1972 through 1983, and began <br />declining in 1987. By 1992, the storage had declined sharply. As shown on Figures I and lA, <br />basin-wide storage at the end of Water Year 1992 was about 13.7 maf less than at the end of <br />1987. Of the total difference, 8.9 maf was in the Upper Basin and 4.8 maf was in the Lower <br />Basin. The 1991 end of calendar year storage in the Colorado River system was about 1.0 <br />million acre-feet less than the 1991 value. <br /> <br />During 1992 storage in most of the major reservoirs on the Colorado River declined and <br />only flows required to meet downstream demands were released. The reduced flows in 1988 <br />through 1992 have resulted in an increase in salinity concentrations in the major reservoirs. <br /> <br />HISTORICAL USES <br /> <br />Estimated historical Lower Basin mainstream and Upper Basin uses for calendar years <br />1975 through 1992 are shown in Table 2 (page 5). <br /> <br />SALINITY CONCENTRATION AT MONITORING STATIONS <br /> <br />Salinity concentrations for the years 1972-1992 at the three stations at which numeric <br />criteria have been set (below Hoover Dam, below Parker Dam, and at Imperial Dam) are shown <br />in Table 3 (page 6). These concentrations are all less than the numeric criteria. <br /> <br />STATUS OF SALINITY CONTROL ACTIVITIES <br /> <br />Bureau of Reclamation! <br />Deuartment of Al!riculture Units BernI! Implemented <br /> <br />Salinity control projects in which both the Bureau of Reclamation (Reclamation) and U.S. <br />Department of Agriculture (USDA) are involved and are in the implementation phase are <br />described under this heading. <br /> <br />Progress during the reporting period on the salinity projects authorized by Title II of P.L. <br />93-320 and P.L. 93-569 and other measures that reduce salinity in the lower main stem of the <br />Colorado River are presented in the paragraphs that follow. A complete description of the <br />projects can be found in the 1990 Review - Water Ouality Standards for Salinity - Colorado <br />River System. Location of existing and proposed salinity control units are shown in Figure 2 <br />(page 7). <br /> <br />Grand Valle.)' Unit (Reclamation-Department of A!!riculture) - The Definite Plan Report <br />and Environmental Impact Statement for the Grand Valley Unit were supplemented to include <br />the Price and Stubb Ditches. The purpose of this supplement is to allow concurrent canal and <br /> <br />3 <br />