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<br />EXTENDING THE USE OF VEGETATION TO IiUPROVE WATER QUALITY <br /> <br />e <br /> <br />The responsibility of states, cities and counties to control pollution from stormwater is ever <br />increasing. The National Pollutant Discharge Elimination System (1'<l'DES) Stormwater Permit <br />Program was mandated by the United States Environmental Protection Agency (EP A) in response <br />to the Water Quality Act of 1972. These regulations require cities, as a municipality serving an <br />urban population of 100,000 or more, to obtain a permit to discharge stormwater into "waters of <br />the United States". These NPDES regulations are directed at a reduction in pollution caused by <br />non-point sources. <br /> <br />The EP A was able to develop a partial monetary estimate of expected benefits for today's <br />stormwater proposed rule. The largest single category of estimated benefits is avoided costs of <br />building or replacing water storage capacity (reservoirs) lost to sediment deposition. EPA <br />estimated that an average of 820,000 acre feet of storage capacity is lost to pollution sources each <br />year. EPA further estimated that one-third of this capacity will be replaced by building new e <br />reservoirs at a cost of $420 to $1500 per acre foot, and two-thirds of this capacity will be <br />restored by dredging at a cost of roughly 53500 to 5 11,000 per acre foot. This yields annual <br />water storage replacement costs of $2 to 56 billion, and EP A estimates that eight percent of these <br />costs ($170 to $510 million) are attributable to stormwater runoff. <br /> <br />Stormwater runoff from lands modified by human activities can hann surface water resources, and <br />in turn, violate water quality standards in two ways: I) by changing natural hydrologic patterns <br />and 2) by elevating pollutant concentrations and loadings. Stormwater runoff may contain or <br />mobilize high levels of contaminants, such as sediment, suspended solids, nutrients, heavy metals, <br />pathogens, toxins, and oxygen-demanding substances. Such contamimmts are carried to nearby <br />streams, rivers, lakes and estuaries. Individually and combined, these pollutants can reduce water <br />quality and threaten one or more designated beneficial uses. <br /> <br />Stormwater discharges generated during construction activities can cause an array of water <br />quality impacts. The biological, chemical, and physical integrity of the waters may become <br /> <br />e <br /> <br />- I - <br />