SITE INFORMATION AND CORRESPONDENCE_CASE 2

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Response to Written Comments -7- 24 April 2007 City of Tracy WWTP San Joaquin County between aluminum toxicity, pH and hardness is not well quantified and recommends that a Water-Effects Ratio (WER) be used to adjust the criteria where necessary. The City has not submitted information supporting a WER for aluminum discharge to Old River. Without this information, the Regional Water Board must use the default assumption of a WER of 1.0, as was done in performing the reasonable potential analysis. As explained in the Fact Sheet, the acid soluble analysis method is allowed to be used to determine compliance with the effluent limits, which should eliminate from consideration aluminum associated with clay particles. The upstream receiving water data for aluminum exceeds both the acute and chronic NRWQC, based on total recoverable analyses. The City is welcome to provide additional upstream data using the acid soluble method. If those data are below the NRWQC, then the reasonable potential analysis could be revised and the need for effluent limits reassessed at that time. CITY OF TRACY - NPDES COMMENT #12: Section IV.A.1.a., Table 4, and Section IV.S.e., Table 9. Copper Limits. The Regional Water Board inappropriately utilizes the copper objective from Sacramento-San Joaquin Basin Plan, Table III-1, in the derivation of proposed effluent limitations instead of the CMC included in the California Toxics Rule. Request: The City requests that the proposed effluent limits for copper be recalculated using only the CTR standards as adjusted by the new Biotic Ligand Model (BLM), and the interim limit be set as a monthly average value. If not enough data exist, the City should be given adequate time under a compliance schedule to perform WER or BLM adjustment to reflect local water quality conditions along with a modification to the reopener at Provision VI.C.1.g. to amend the final limits based on the WER or BLM adjustment. RESPONSE: The Policy for Implementation of Toxics Standards for Inland Surface Waters, Enclosed Bays and Estuaries of California (a.k.a., State Implementation Policy or SIP) in the fourth footnote on Page 1 states, "if a water quality objective and a CTR criterion are in effect for the same priority pollutant, the more stringent of the two applies." This is consistent with guidance supplied by Kathleen Goforth, Water Quality Standards Coordinator for USEPA, Region 9. In an email reply to an inquiry from Regional Water Board basin planning staff, dated 24 August 2004, Ms. Goforth states, "Where there are both State and federally promulgated criteria, if the State criteria are more stringent than the federal criteria, the State's more stringent criteria apply. This is explicitly stated in both the NTR [40 CFR 131.36(c)(1)] and CTR [40 CFR 131.38(c)(1)]. Conversely, if the federal criteria are more stringent than the State criteria, then the federal criteria apply." Federal regulations in 40 CFR 131.38(c)(1) state, "The criteria in paragraph (b) of this section apply to the State's designated uses cited in paragraph (d) of this section and apply concurrently with any criteria adopted Regional Water Quality Control Board, Central Valley Region Board Meeting— 3/4 May 2007 Item#17