FIELD DOCUMENTS AND WORK PLANS 2000-2003

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%L RLEY COOLNG 70WER*IPANY •GROUNDWATER EX-1 2ACTION AND =-—kTI'1ENr SYSTEM SAN JOAQLZ;COLLA-TY RESPONSE TO CObDGNTS 0 January 2003 pre._de hydraulic conrm'_ity with tae Calaveras River. The lack of dilution re_.:'-s in more stringers= effluent limitations tc protect drinking water stane_ and aquatic life. The Discharger may elect to conduct flow mord.oring of the SDC to determine the actual flow regime, and to m'-e extent seasonal zz—s milative capacity is available in receiving water to accommodate constituents in e effuent which exceed reasonable potential c feria, this permit contains a re- opener to consider final eMuent limitations based upon demonszated assim;-s-4ve capacity. The Discharge-may submit additional receiving wate- zharacterz_on to remonstrate the flow -:gime and pollutant assimilative capad and ask e Re onal Board to re-eg.m the permit to consider this new infor^ation. • Aquatic toxicity testing conducted since 1995 has shown that the 1fCTC discharge consistently meets the aquatic to dciry criteria. Response: Short-term whole effluent toxic:-~-(WET)tests are used as par: c::he wa_?nt of evidence approach to assessing toxics control and toxicity. In the Technical Support Doc=ent for«ater Q.:=ry-based Toxics Control (TSD. March 1991), USEPA --commends an inte=ated chemical-speci5c, whole e_ ent and bioassessment approach to fu y protect aquatic habitats. The-`CTC discharge enters a receiving water body with aquatic life beneficial uses. A noted in the TO Factsheet, individ.ral priority pollutants, including copper and hexavalent chromium, have been identified :n the treated effluent at ccncentrations which exceed appropriate ac::atic life criteria, therefore indi�:dual po''-utant effluent limita:�ons and monitor:^_= are required. • Tl:e RQWCB set the cr.ginal TDS permi. limit at 500 mgIT and subse. Fnrly raised the limit to 1000 mg17 because the groundwater had naturally oc r ting levels of TDS higher titin 500 M_-7 • T1-0 RWQCB presents ro factual data that the 1000 mg/7 TDS adversely _sects az,'cultural crops. The RWQCB simply states "its presence can be z-owth limiting to certain agricultural crops". In fact, based on the RWOCB desc--cion of the Stockton Diver-.7,g Canal, during cite dry period when. the MCTC s the or.:-; water in the Carz: we find is diffcu'. to imagine that after evapora _r and percolation that there s sufficient-,cater for irrigation use. • Tne TDS limit should be based on the dilution during the period the Calaveras River is diverted through the Canal. The RWQCB states that r ; are required to apply the beneficial uses of municipal and domestic supply -o the Stockton Diverting Canal because Stare Board Resolution No. 88-5.5 was incorporated into the 3asin Plan. The Stockton Diverting Canal is not ce-.�cred to the Calaveras River during the dry period and therefore does not ,cater with the Calaveras River during this period. We believe that during.-._ dry period the Canal shouic not be ccrsiderec:art of the Calaveras River.