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<br /> <br />page 2-7 indicates salinity damages resulting from long-term continued use at various levels of <br />salinity. With current salinity concentrations, these damages are estimated to be over $750 <br />,. million per year i If the proposed plan of implementation for salinity control, as set forth in this <br />Review, is not implemented, these damages could double by the year 2015. <br /> <br />Agricultural water users suffer economic damage as a result of using highly saline waters <br />through reduced crop yields, added labor costs for irrigation management, and added drainage <br />requirements. The urban user incurs additional costs due to more frequent replacement of <br />plumbing and water using appliances, use of water softeners and the purchase of bottled water. <br />Industrial users' and water treatment and waste water utilities incur reductions in the useful life <br />of system facilities and equipment from increased levels of salinity. <br /> <br />A significant impact in the Lower Basin is that imposed by local and regional water <br />quality standards and management programs, to protect ground water supplies. Regulatory <br />agencies have placed restrictions on reuse or recharge of waters that exceed specified salinity <br />levels. If the river's salinity continues to increase, these regulatory actions would result in <br />additional expensive treatment of water prior to reuse or disposal of such waters. If disposal <br />options are selected, additional costly alternative sources of water must be developed or imported <br />to meet the demands previously met or that could be met by water reuse. <br /> <br />The goal of Colorado River salinity control is to maintain the flow-weighted average <br />annual salinity at or below the numeric criteria of the salinity standards. The effort is not, <br />however, intended to counteract the salinity fluctuations that are a result of the highly variable <br />flows caused by climatic conditions, precipitation, and snowmelt. Therefore, to evaluate the <br />effectiveness of the salinity control program, water quality data were adjusted to reflect long- <br />term mean water supply. <br /> <br />For Progress Report 16, Reclamation evaluated whether current salinity control efforts <br />are sufficient to meet the numeric criteria of the salinity standards under the current level of <br />development in the basin. The study found the numeric criteria will not be exceeded at any of <br />the three stations under the "present" or existing (1991) level of development and salinity <br />control. Table 2.2 shows a comparison of the numeric criteria to the adjusted flow-weighted <br />average annual salinity for existing conditions at the three Lower Basin monitoring stations. <br />Observed salinity concentration at each of these three stations is much lower than the adjusted <br />values, due to the unusually wet hydrology during the mid 1980's and the storage of this water <br />in the main stem reservoir system. <br /> <br />Salinity concentrations caused by natural fluctuations of flows in the basin differ from <br />the salinity that would be observed if the long-term mean water supply condition were to occur. <br />The water quality standards allow for the variation which is due to natural fluctuation in the <br />hydrologic conditions. <br /> <br />2-8 <br />