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<br />~ <br />\-6 <br />o <br />~ <br /> <br />(e.g., the 1990 Review contained a plan of implementation through the year 2010). In this <br />triennial review, the Forum not only looked at the amount of salt that needs to be removed by the <br />year 2015, but also determined the salt removal necessary when there is full development of the <br />compact-apportioned waters of the Colorado River. In order to comply with the numeric criteria, <br />the Forum has determined that at full development of the compact-apportioned waters, 1.8 million <br />tons of salt annually must be removed or prevented from entering the system, The plan of <br />implementation (described in Chapters 4 and 5) includes projects that have the potential for <br />meeting the goal of removing the required salt tonnage. <br /> <br /> <br />Numeric Criteria for Salinity <br /> <br />Federal ReltUlatlon <br /> <br />The federal regulation promulgated (see Appendix A) by the EPA required the adoption <br />of numeric criteria by the states. The observed flow-weighted average annual salinity for the year <br />1972 was determined by Reclamation from daily flow and salinity data collected by the U.S. <br />Geological Survey and Reclamation and became the numeric criteria as follows: <br /> <br />Below Hoover Dam <br />Below Parker Dam <br />At Imperial Dam <br /> <br />723 mg/L <br />747 mg/L <br />879 mg/L <br /> <br />There is no inference that 1972 was chosen as the basis for establishing the numeric criteria <br />because that year represented a typical or average year. Further, the plan of implementation is <br />designed to offset the effects of human activity under long-term mean water supply conditions of <br />15 million acre-feet per year. The Forum's basis for selecting these stations is because of their <br />proximity to key diversion facilities on the lower Colorado River. The State of Nevada diverts <br />Colorado River mainstem water from Lake Mead for use in the Las Vegas area, and its return <br />flows move into the Lake and are part of the water supply available below Hoover Dam. The <br />Metropolitan Water District of Southern California and the Central Arizona Project divert water <br />from Lake Havasu, impounded behind Parker Dam, for many millions of water users in southern <br />California and central Arizona. The large agricultural areas in the Imperial and, Coachella Valleys <br />in California and the Yuma area in Arizona and California are served by diversions made at the <br />Imperial Dam. All lower basin water users suffer adverse impacts of high salinity to some degree. <br /> <br />The criteria were not established to protect human health or fish and wildlife values. The <br />salinity .levels that are anticipated in the future, even without salinity control efforts, have not been <br />shown to have adverse effects on human health or wildlife. Thus, this program is different than <br />most other water quality standards compliance programs. <br /> <br />The Forum, responding to the requirements of Section 3031Cl of the Clean Water Act, has <br />conducted the review contained in this report. The Forum concludes that the numeric criteria need <br />not be revised and should continue to be the values used for the standards. <br /> <br />3-2 <br />