Challenges and Obstacles for Small Municipalities seeking to reduce Illicit Stormwater Discharges

摘要

Polluted stormwater runoff is commonly transported through Municipal Separate Storm Sewer Systems (MS4s), from which it is often discharged untreated into local waterbodies. Storm water is runoff from rain or snow melt that runs off surfaces such as rooftops, paved streets, highways or parking lots and can carry with it pollutants such as: oil, pesticides, herbicides, sediment, trash, bacteria and metals. The runoff can then drain directly into a local stream, lake or bay. Often, the runoff drains into storm drains which eventually drain untreated into a local waterbody. In the United States, several phases have been implemented beginning with counties with populations greater than 100,000 or more to obtain permit coverages for their stormwater discharges. The second phase requires regulated smaller in urbanized areas, as well as populated areas the urbanized areas that are designated by the permitting authority to obtain permit coverage for their stormwater discharges. Additionally, municipal or urban areas commonly include large impervious surfaces which contribute to an increase in runoff flow, velocity and volume. As a result streams are hydrologically impacted through streambed and channel scouring, instream sedimentation and loss of aquatic and riparian habitat. In addition to hydrological impacts, large impervious surfaces contribute to greater pollutant loading, resulting in turbid water, nutrient enrichment, bacterial contamination, and increased temperature and trash. This paper presents best management practices collected from several municipalities seeking to reduce illicit stormwater discharges.