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<br />CHAPTER II <br /> <br />NEED FOR ACT10~ <br /> <br />. <br /> <br />Table I <br />Salinity control standards <br /> <br />Colorado River <br />Annual <br />flow-weighted <br />concentration <br />(mg/Ll <br />72l <br />747 <br />879 <br /> <br />for the Lower <br /> <br />w <br />.J:>, <br />00 <br />-.J <br /> <br />Station <br />Below Hoover Dam <br />Below Parker Dam <br />At Imperial Dam <br /> <br />The goal of the salinity control program is to maintain concentra- <br />tions at or below these criteria.. Depletions within the Colorado River <br />Basin are projected to increase from 9.6 million acre-feet per year in <br />1983 to 12.6 million acre-feet by 2010. With full development of the <br />compact-apportioned waters, the depletions could increase to 15 million <br />acre-feet annually. Annual salinity concentrations at Imperial nam are <br />estimated to increAse from the 1983 measured, avera~e level of 710 m~/L <br />to an average of 1.012 Illg/L by 2010 unless additional control measures <br />are implemented to prevent the salinity increase, <br /> <br />. <br /> <br />Based on studies conducted by the Bureau of Reclamation anrl the <br />Soil Conservation Service, full implementation of all authorized salin- <br />ity control measures (Reclamation and SCS measures authorized for con- <br />struction) could maintain the salinity standard at !mperial Dam unt1.l <br />ilbout 2005 if fully implemented..!..! By 20In, the sil.1intty levels are <br />expected to reach 904 mg/L and will continue to incre.iJ.se with further <br />development. 1)l1ring some years, the concentrations woulrt exct>i"d those <br />predicted levell'!. Table 2 shows expected salinity levels in the :-,ear <br />2010 with and without additional salinity control measures. <br /> <br />Table 2 <br />Mean annual salinity at Imperial Dam <br />(Unit--mg/L) <br /> <br />1981 <br />.!/ 71 0 <br />.!.I]IO <br /> <br />2010 <br /> <br />Without additional salinity <br />control measures <br />With full implementation of <br />salinity control measures <br />Numeric criterion at <br />Imperial Dam <br />!I Historical mean. <br /> <br />1,012 <br /> <br />904 <br /> <br />879 <br /> <br />879 <br /> <br />It is unlikely all of the authorized salinity control measures will <br />be fully implemented. To attain the adopted salinity standard, addi- <br />tional salinity control, water du~m~ntation. or management steps will <br />be necessary. Thus, beneficial use, weather modification, vei!;etatlon <br />management, watershed improvements, and possiblY other measures remain <br />to be considered and studied in detail. <br /> <br />. <br /> <br />!I U.S, Department of <br />Water, Colorado River Basin, <br /> <br />the Interior, <br />Pro~ress Report <br /> <br />Janu.i\ry <br />So, 12, <br /> <br />1985. <br /> <br />~l ity of <br /> <br />9 <br />