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INFORMATION SHEET • • 12 <br /> WASTE DISCHARGE REQUMMENTS ORDER NO.R5-2002-XXXX <br /> MARLEY COOLING TOWER COMPANY <br /> STOCKTON, SAN JOAQUIN COUNTY <br /> For determining whether there is reasonable potential for an excursion above this narrative <br /> objective, the Regional Board used the second method prescribed by 40 CFR 122.44(d)(vi) for <br /> determining reasonable potential, which relies on USEPA criteria and other information. The <br /> Regional Board chose this method because USEPA's recommended ambient water quality criteria <br /> for chlorine have been developed using methodologies that are subject to public review, as is the <br /> individual recommended criteria guidance document. USEPA's ambient water quality criteria for <br /> protection of aquatic life are 11 ttg/L (ppb) as a 4-day average (chronic) concentration, and <br /> 19 µg/L(ppb) as a 1-hour average (acute) concentration for total residual chlorine. Based upon <br /> results of monitoring, the Regional Board finds that the discharge does have a reasonable potential <br /> to cause or contribute to an in-stream excursion above a water quality objective. This Order <br /> includes new maximum daily(0.02 mg/L(ppm)) and average monthly(0.01 mg(L (ppm)) effluent <br /> limitations for residual chlorine based upon the USEPA criteria. Previous Orders did not include <br /> effluent limitations for chlorine, and it is unknown whether the Discharger can immediately <br /> comply with these new limitations. <br /> Toxicity <br /> In the past; results of effluent chronic toxicity testing using EPA/600/4-91/002 have indicated <br /> sporadic instances of reduced Ceriodaphnia Dubia reproduction. Also, previous Order No. 93-221 <br /> included an effluent limitation for acute toxicity. This new Order retains an effluent limitation for <br /> acute toxicity, and includes continued monitoring of effluent and receiving water for chronic <br /> toxicity. <br /> JMEUpdate/S4ug02 - <br />