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Tri-Regional Recommendations Page 9 of 24 Appendix A Notes for Table i (a) Water Quality Objectives for groundwater from the Water Quality Control Plan(Basin Plan)for the Sacramento River Basin and the San Joaquin River Basin Fourth Edition Similar language is found in the Tulare Lake Basin Plan Chemical Constituents Ground waters shall not contain chemical constituents in concentrations that adversely affect beneficial uses At a minimum ground waters designated for use as domestic or municipal supply(MUN)shall not contain concentrations of chemical constituents in excess of the maximum contaminant levels(MCLS)specified in the following provisions of Title 22 of the California Code of Regulations, which are incorporated by reference into this plan Tables 64431-A(Inorganic Chemicals)and 64431-B(Fluonde)of Section 64431,Table 64444-A(Organic Chemicals)of Section 64444 and Tables 64449-A(Secondary Maximum Contaminant Levels-Consumer Acceptance Limits)and 64449-B (Secondary Maximum Contaminant Levels-Ranges)of Section 64449 This incorporation-by-reference is prospective including future changes to the incorporated provisions as the changes take effect At a minimum water designated for use as domestic or municipal supply(MUN)shall not contain lead in excess of 0 015 mgll To protect all beneficial uses the Regional Water Board may apply limas more stringent than MCLS Toxicity Ground waters shall be maintained free of toxic substances in concentrations that produce detrimental physiological responses in human plant animal or aquatic life associated with designated beneficial use(s) This objective applies regardless of whether the toxicity is caused by a single substance or the interactive effect of multiple substances Tastes and Odors Ground waters shall not contain taste-or odor-producing substances in concentrations that cause nuisance or adversely affect beneficial uses (b) Pnmary MCLS are human health based but also may reflect other factors relating to technologic and economic feasibility of attainment and monitoring in a water distribution system and at the tap These factors may not be relevant for the water resource (c) 1-in-a-million cancer risk estimate derived from published oral cancer slope factor by assuming 2 litersiday water consumption and 70 kg body weight (d) If adopted as proposed this limit would become the numerical limit used to interpret this objective (e) Health advisory=4000 ug/L.for 10 day exposure or less No lifetime exposure advisory has been developed However lifetime health advisories are normally at least ten-fold lower than 10-day advisories Therefore a level of 400 ug1L would be a reasonable estimate of a lifetime protective level (f) Secondary MCLs are human welfare based but also may reflect other factors relating to technologic and economic feasibility of attainment and monitoring in a water distribution system and at the tap These factors may not be relevant for the water resource (g) Value listed is for 1 3 5-tnmethylbenzene Taste and odor treshold should be similar for 1 2 4-tnmethylbenzene (h) Liability under Proposition 65 may also exist for responsible parties where levels in water exceed 0 25 uglL (i) Listed value assumes 2 literstday water consumption 70 kg body weight and 20%relative source contribution from drinking water (I) Concentrations of individual PAHs are adjusted by dividing the concentrations by the potency equivalency factors(PEFs)in the table on the following page The limit applies to the sum of these adjusted concentrations For definitions of terms and acronyms used to'fable 1,please see the staff report,A Complication of Water Quality Goals,available on the internet at http www swrcb ca govlrwgcb5lavailable_documents/wq_goals pages 9 to 13 I No policy or regulation is expressed or intended Jon Marshack,CVRWQCB 1 April 2004