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COLORADO DEPARTML•NT OF NLAL771, Warcr Quality Gnirrol Divrcion Rainrrnlc - Pagc IS, Pennir Nn. CO-00326.t3 The flaws and cnrrecponding 1WC jot the approprinre discharge point nre: Discharge Point Chronic Law Flow,: : Fari[iry Design :Flaw,: IWC, (rXo) 006 6.0 cfs J.07 34 The /WC jar this permit is 34'Yo, which represents a wastewater concentration of 34'R, ejflucnt to 66'Yo receiving stream 7herejore, chronic conditions are applicable to this permit. cJ Qtronic WET [imitations: Because of the pruence of muair in the discharge, the Division believe there is reasonable potential jot the discharge to iutrfere with attainment of applicable water quality class fkations or standards. Because of this condition, the chronic limit has been incorporated imo the permit and become effective January 1, 1997. Prior to the chronic limit becoming effedivt, the permitter is required to conduct routine monitoring. The ruults of the toting are to be reported on Division approved forms. 7lie pesmittee wiU be required to conduct two type of statistical derivations on the data, one looking for any statistically significant difference in toxicity between the control and the ejjluent concentrations and the second idemEying the IC25, should one exist. Both sus of calculations will look at the full range of toxicity (lethality, growth and reproductionJ. Jf a level of chronic tosicccity occurs, such that there is a statistically significant difference in the lethality (at the 95% confidence kvelJ buween the control and any ejjluem concentration less than or equal to the Instream Waste Concentration (/WCJ and if the lethality /C2S G the IWC, the paanittee wiU be required to follow the automatic rnmpliance schedule idem~ed in Pan LB of the permit, if the observed toxicity is due to organism lethality. Once the chronic luhality limitation becomes effective, only exceedance of the limitation spec~rd in Pan I.A. 2. will trigger the requiremuu jar conducting the automatic rnmplianct schedule idemi~ in Pan I.B. of the permit. Prior ro and after the limitation 6econus effective, if the toxicity is due to difference in the growth of the fathead minnows or the repraduaian ojlhe Ceriodaphnia, no brvnrdiate action on the pan of the permilJee will be required However, this incident, along with other WET data, will be etnluated by the Division and may form the basis for reopening the permit and including additional WET limiu or other requirements. dJ General Information: The permitter should read the WB/'teting sections of Pan l.A. and J.B. of the permit carefully. The permit outline the tut requiremenu and the required folbw-up actions the pcrndttct must rake to resolve a tozicRy incident. The permitter should trod, along with the documents listed in Pan LB ojthe permit, the Colorado Water Quality Control Division BiomonitorinA Guidance Documem. dated July I, 1993. This documuu outlines the criteria used by the Division in such areas as granting relief from WET testing, modhng test muhods and changing tut specie. 7ht permittee should be aware that some of the rnnditions outlined above may be subject to change if the facility experiences a change in discharge, as outlined in Pan ILA.I of the permit. Such changes shall be reported to the Division imrnediatety.