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r a v Note: 4-daffy averaX�e,24-hour average,or chronic criteria should be used as water qualitygoals whenever available to protect the surface water resource for the -- long terrn. • "Water Quality Advisories" published by the U.S. EPA,Office of Water Regulations and Standards; • Quality Criteria for Water(the"Red Book")published by EPA in 1976; • Water Quality Criteria,1972(the`Blue Book")published by EPA in 1973; • The Department of Fish and Game and staff of our Standards,Policies and Special _. Studies unit may also supply criteria for fish and wildlife protection; Agricultural Use • Water Quality€or AQticulture published by the Food and Agriculture Organization of the United Nations in 1985; - Other Uses • Water Quality Criteria written by McKee and Wolf and published by the State Water Resources Control Board in 1963 which contains criteria for human health ,and welfare,aquatic life,agricultural use,industrial use,and various other uses. Ta protect the maximum number of beneficial uses,the most restrictive(lowest), applicable,and jusrifiable water quality criteria should be selected. Due to the rapidly cleanging data base on the health and environmental effects of chemicals,caution should be observed in selecting among the various water equality criteria to be sure that the most recent information is utilized. The original literature should be consulted whenever possible to determine the applicability and limitations of the criteria being selected. Other government agencies,such as the California Department of Health Services,the California Department of Fish and Game,and the U.S. Environmental Protection Agency may be consulted for up-to-the-minute information. It is common practice to rely on Primary MCLs as"enforceable water quality standards"for human health. However,care should be taken in the application of Primary MCLs to the protection of sources of drinkingg water. A common example of incorrect application is the use of the total trihalomethane(TITIM)MCL for the protection of ground water from chloroform. Chloroform is one of the four chemicals covered by the term"trihalomethanes". The TTHM standard of 100µg/1 is 18 to 526 times higher than the 1-in-a-million incremental cancer risk estimates for chloroform. EPA has stated that the MCL for TTHMs was based mainly on technology and economics. Therefore,this standard does not clearly protect the beneficial use for domestic supplyof waters of the State. The MCL for T7FfMs was derived,for application to dinking water as it is delivered to consumers after disinfection by — chlorination,' balancing the benefit provided by the chlorination process (elimination of�pathogens in drinking water)with the health threat posed by the trihaloinethaneby-products of this process. In the case of contaminated ground water this type of cost/benefit balancing is not germane,and so the MCL does not apply to the protection of the ambient quality of domestic water supply sources. $electing Watcr Quality Goals Page 3 Mar i4 9