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• probable human carcinogens are also included. contained the Central Valley Regional Water Quality Some Water Quality Advisories also contain i Control Board staff report,A Compilation of Water aquatic life criteria. Quality Goals. J Suggested No-Adverse-Response Levels(SNARLS)— Selecting Between Available Water Quality Goals These human health-related criteria are published by the National Academy of Sciences in Drinking To protect the maximum number of beneficial uses,the Water and Health,Volumes 1,3,4,5,6,and 7. most restrictive(lowest),applicable(under the benefi- (U.S.EPA's health advisories were formerly cial use designations and water quality objectives in the published as SNARLS.) SNARL values do not Water Quality Control Plans)water quality values include a consideration of cancer nsk. Incremental should be selected as the water quality goal for a cancer risk estimates are also presented separately particular site and pollutant. Due to the rapidly for carcinogens. changing data base on the health and environmental effects of chemicals,caution should be observed in J Estimated Permissible Ambient Goals— selecting among the various water quality values to be sure that the most recent information is utilized. The Published by U.S. EPA in 1977 in Multimedia original literature should be consulted whatever Environmental Goals for Environmental Assessment, possible to determine the applicability and limitations these critena are estimated from occupational of the values being selected. Other government exposure to airborne pollutants and,as such,are agencies,such as the California Department of Health not very reliable as water quality goals. Therefore, Services, the California Department of Fish and Game, they should only be used if no other criteria are and the U.S.Environmental Protection Agency may be available. consulted for up-to-the-minute information. Other sources of water quality goals include: It is common practice to rely on Primary MCLS as "enforceable standards" for human health. However, J Water Quality for Agriculture,published by the Food 1 MCLS are intended to apply to water within a drinking and Agnculture Organization of the United water distribution system. Care should be taken in the Nations in 1985,contains criteria protective of application of Primary MCLs to the protecdamof agricultural uses of water. sources of drinking water. A common exan46W incorrect application is the use of the total triholo- J Water Quality Criteria,written by McKee and Wolf methane(TTHM)MCL for the protection of ground and published by the State Water Resources water from chloroform. Chloroform is one of the four Control Board in 1963 and 1978,contains criteria chemicals covered by the term"tnhalometharm". for human health and welfare,aquatic life,agricul- These probable human carcinogens are formed in tural use,industrial use,and various other benefi- drinking water by the action of chlorine,used4or tial uses. This document is available from the disinfection,on organic matter present in the raw National Technical Information Service(NTIS)as source water. The TT[ M Primary MCL of 100µg/I is Publication No.PB 8218824. 18 to 526 times higher than the published one-ina- million incremental cancer risk estimates for chloro- .J The California Department of Fish and Game can form. U.S. EPA has stated that the MCL for Tl'HMs also supply criteria for fish and wildlife protection. I was based mainly on technologic and economic 1 considerations. Therefore, this drinking water stan- Manv of these numencal water quality goals and the dard does not clearly protect the beneficial use for numerical water quality objectives from the State municipal and domestic supply of waters of the state. Water Board's state-wide Water Quality Control Plans The MCL for TTHMs was derived by balancing the have been summarized in the tables and graphs benefit provided by the chlorination process(elimina- /on B.Marshaek,D.Env. Page 7