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<br />USBRIMWD SALINITY MANAGEMENT STUDY <br />FINAL REPORT <br /> <br />. <br /> <br />EXECUTIVE SUMMARY <br /> <br />W <br />'-'1 <br />-<I <br />Cv <br /> <br />This report presents the findings and recommendations of a two-year technical investigation of <br />the impacts of total dissolved solids or salinity to our region. The Salinity Management Study <br />(Study) was conducted in close collaboration with member agencies and numerous other <br />concerned agencies. The United States Bureau of Reclamation (USBR) was a primary study <br />partner, contributing financial assistance under its congressional authority to develop a <br />regional water recycling plan for Southern California. High salinity is a significant constraint <br />to water recycling. <br /> <br />For analytical purposes, the Colorado River Aqueduct (CRA) was considered full for the <br />study period, consistent with the objectives of the California 4.4 Plan. <br /> <br />BENEFITS OF REDUCED SALINITY <br /> <br />When salinity levels of imported water are reduced, the region benefits from: <br /> <br />o Improved use oflocal groundwater and recycled water; and <br />o Reduced economic impacts to water conswners and utilities. <br /> <br />. It is estimated that $95 million per year of economic benefits would result if Metropolitans <br />CRA and State Water Project (SWP) waters were to simultaneously experience a <br />100 milligram per liter (mgIL) reduction in salt content over their historic average. <br />Conversely, about the same dollar amount of impacts would result if imported water salinity <br />increased by 100 mgIL. Primary salinity impact categories include residential, commercial, <br />industrial and agricultural water users; groundwater and recycled water resources; and utility <br />distribution systems. <br /> <br />SALT SOURCES <br /> <br />About half of the regions salt is contributed by imported water and the other half by local <br />sources. The CRA constitutes Metropolitans highest source of salinity, averaging about <br />700 mgIL. Hardness comprises about one-half of the CRA salt load and causes troublesome <br />scaling problems to indoor water uses by residential, commercial and industrial entities. The <br />SWP provides Metropolitan with lower salinity water (250 mgIL on the East Branch and <br />325 mgIL on the West Branch on average) which can be used to blend down CRA <br />concentrations. SWP salinity levels can change rapidly in response to hydrologic conditions. <br />Such changes are noticeable and disruptive as compared to the very gradual, almost <br />imperceptible changes which occur in local streams, groundwater and wastewater collection <br /> <br />. <br /> <br />BOOKMAN-EDMONSTON <br />ENGINEERING, INC. ES-l <br />O:ILOCALRESI,ANDYSlSALlNlTYVUNE19981F-XECSUM.DOC Last printed 07/20/989:23 AM <br /> <br /> <br /> <br /> <br /> <br /> <br />," ~ ,h",,-/;:t <br />