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<br />yields, altered crop patterns, increased leaching and drainage require- <br /> <br />ments, and increased management costs. Agricultural losses begin when <br /> <br />salinity levels reach 700-850 mg/L, depending upon soil conditions and the <br /> <br />type of crop grown. <br /> <br />Salt loading occurs as a result of weathering and the dissolution of <br /> <br />soluble salts in soil and substrata. In addition, salt concentration <br /> <br />occurs due to consumptive use, such as agricultural or industrial <br /> <br />applications of water in the basin. Generally, the application of <br /> <br />irrigation water results in increased salt concentrations because of 90th <br /> <br />salt loading and salt concentration. The salt load fluctuates annually <br /> <br />with the overall basin water supply. Without control measures and as the <br /> <br />States continue to develop their compact-apportioned water, the salinity <br /> <br />at Imperial Dam is projected to increase, possibly reaching a level of <br /> <br />1,140 mg/L at the dam by the year 2000. <br /> <br />In response to the Federal Water Pollution Control Act Amendments of <br /> <br />1972 (P.L. 92-500), the Colorado River Basin States adopted salinity <br /> <br />control standards for the Colorado River. These standards, shown below <br /> <br />for three stations on the Lower Colorado River, have been approved be the <br /> <br />Environmental Protection Agency: <br /> <br />Station <br /> <br />Annual flow-weighted <br />contentration (mg/L) <br /> <br />Below Hoover Dam <br />Below Parker Dam <br />At Imperial Dam <br /> <br />723 <br />747 <br />879 <br /> <br />The CRWQIP goal is to maintain Lower Colorado River salinity levels <br /> <br />at or below the 1972 historical levels while the Basin States continue to <br /> <br />develop their compact-apportioned waters. To attain this goal,CkQlji~ed <br /> <br />2.8 million tons of salt per year must be intercepted before entering the <br /> <br />14 <br />