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<br />I <br />I <br />I <br />I <br /> <br />DRAINAGE CRITERIA MANUAL (V. 3) <br /> <br />STORMWATER QUALITY MANAGEMENT <br /> <br />3. Destruction of freshwater wetlands. riparian buffers and springs. Runoff can effect wetlands <br />because of changes In vegetation, This in turn results in changes or loss of habitat, the community <br />of organisms (diversity, kind, density, loss of particular biota) and permanent loss of wetlands. <br /> <br />Stormwater runoff into lakes has some unique effects on water quality. These include: <br /> <br />I I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />1. Lakes respond more to the mass of a constituent and flow volume. The response time to storm <br />events is measured in days or weeks unlike streams which show effects within hours or days. This <br />makes it more difficult to tie a problem to a particular storm event. <br /> <br />2. The major notable visible impacts of stormwater is floating refuse and shore damage. The major <br />impact would be the nutrient enrichment. This can result in the undesirable growth of aquatic <br />plants. <br /> <br />3, Lakes do not flush contaminants as quickly as streams. They frequently act as sinks for metals <br />and other sedimented materials. This means that they take longer to recover if contaminated. <br /> <br />Water quality impacts also result from the washing of materials from the impervious areas of the urban <br />watershed. Section 2.2 includes sampling runoff data from urban areas. <br /> <br />Table 1.2 lists the sources of runoff and the types of pollutants expected. <br /> <br />1.2 NPDES Permit Regulations <br /> <br />In 1972, Congress passed what is currently referred to as the Clean Water Act (CWA), The Act <br />established the National Pollutant Discharge Elimination System (NPDES) program, Efforts, until recently, <br />under the NPDES program have focused on non-stormwater discharges from industries and municipal <br />wastewater treatment plants. In the last 10 years as non.stormwater discharges have been adequately <br />addressed, efforts have begun by EPA to expand the NPDES program to cover stormwater discharges. <br /> <br />1.2.1 Phase I Stormwater Regulations. As effective controls have been implemented on non. <br /> <br /> <br />stormwater discharges, it has become more evident that diffuse sources can create impacts on water <br /> <br /> <br />quality. In 1987, the CWA was revised to address stormwater discharges. The CWA called for a two phase <br /> <br /> <br />permitting strategy. Phase I affected, <br /> <br />I <br /> <br />. Any discharge of stormwater that was permitted under the NPDES program prior to February 4, <br />1987. <br /> <br />. Discharges associated with industrial activity. <br /> <br />I <br />I <br />I <br /> <br />X'X.98 <br />Urban Drainage and Flood Control District <br />DE NI1g1599.docJ982720004. DOC <br /> <br />50.3 <br />