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City of Stockton and County of San Joaquin Page 21 <br /> NPDES Permit CAS0083470 <br /> Response to Comments <br /> Reflecting this legislative intent,EPA's Phase I Storm Water regulations require municipalities to <br /> develop management programs to control discharges of pollutants (Le., what is practicable)rather <br /> than requiring end-of-pipe treatment(i.e., what is not practicable). (Section 122.26(d)(2)(iv) <br /> requires the applicant to identify in part 2 of the application, to the degree necessary to meet the <br /> MEP standard, additional prevention or control measures which will be implemented during the life <br /> of the permit.) (The permit application requirements in today's rule requires the applicant or co- . <br /> applicants to develop management programs for four types of pollutant sources which discharge to <br /> large and medium municipal storm sewer systems.) This shift toward a programmatic approach to <br /> controlling storm water discharges (and away from the traditional, strict end-of-pipe approach) was <br /> appropriate, according to EPA, for several reasons: <br /> First, discharges from municipal storm sewers are highly intermittent, and are usually <br /> characterized by very high flows occurring over relatively short time intervals. For this reason, <br /> municipal storm sewer systems are usually designed with an extremely high number of outfalls <br /> within a given municipality to reduce potential flooding. Traditional end-of-pipe controls are <br /> limited by the materials management problems that arise with high volume, intermittent flows <br /> occurring at a large number of outfalls. Second, the nature and extent of pollutants in discharges <br /> from municipal systems will depend on the activities occurring on the lands which contribute <br /> runoff to the system. Municipal separate storm sewers tend to discharge runoff drained from <br /> lands used for a wide variety of activities. Given the material management problems associated <br /> with end-of-pipe controls,management programs that are directed at pollutant source are often <br /> more practical than relying solely on end-of-pipe controls. <br /> The Phase I Storm Water regulations thus require municipalities to develop storm water <br /> management programs that,to the maximum extent practicable, control the discharge of pollutants <br /> from their MS4s. Impracticable end-of-pipe controls, that might be appropriate for industrial <br /> discharges to meet water quality standards (WQS), are not required. <br /> Response: Comment noted. The Tentative Order implements the management program approach <br /> endorsed by USEPA and does not seek to impose end-of-pipe controls because they are <br /> impracticable at this time. See also the response to the City's comments No.1. <br /> 11. Comment: "The Basin Plan ' <br /> Under state law, in issuing waste discharge requirements, regional boards are to implement any <br /> applicable water quality control plans (i.e.,basin plans). See Water Code Section 13263(a). <br /> According to the Sacramento River Basin and San Joaquin River Basin Plan, the"municipal permits <br /> establish controls to reduce/eliminate pollutants to the maximum extent possible <br /> (practicable?)(MEP) and to effectively prohibit non-storm water discharges to storm sewer <br /> systems."Basin Plan,p. IV-3.00 (Sept. 1, 1998). To the extent that the Tentative Order attempts to <br /> hold the Permittees to a standard stricter than MEP, the Regional Board would not be implementing <br /> the Basin Plan and therefore would be in violation of Water Code section 13263(a). <br /> Response: The Tentative Order is intended to require that pollutants be controlled to the maximum <br /> extent practicable. It is not inconsistent with the cited provision of the Basin Plan or with applicable <br />