Unfiltered Stormwater runoff into streams, lakes, ponds, and oceans can have a significant impact on water quality. As stormwater flows over these sites, it picks up pollutants like sediments, nutrients, pathogens, debris, toxins and other various chemicals.
Polluted stormwater runoff not only lowers water quality but can harm or kill fish and other wildlife. For example, excessive amounts of sediment in water can destroy aquatic habitats.
This type of pollution is known as nonpoint source pollution (NPS) which contributes to one-third to two-thirds of our nation’s water quality problems according to the EPA.
Nonpoint source pollution comes from rainwater which runs overs lawns, parking lots, city streets, forest, and construction sites associate with both residential and urban areas.
Urban Runoff Pollutants (US EPA, 1993Urban Runoff Handbook, page 5)
|Sediments – TSS, turbidity, dissolved solids||Construction sites, urban/agricultural runoff, landfills, septic fields||Habitat changes, stream turbidity, recreation and aesthetic loss, contaminant transport, bank erosion|
|Nutrients – Nitrate, Nitrite, Ammonia, Organic Nitrogen, Phosphate, Total Phosphorus||Urban/agricultural runoff, Landfills, septic fields, atmospheric deposition, erosion||Algal blooms, ammonia toxicity, nitrate toxicity|
|Pathogens – Total and fecal coliforms, fecal streptococci, viruses, E.Coli, Enterococcus||Urban/agricultural runoff, septic systems, illicit sanitary connections, boat discharges, domestic/wild animals||Ear/intestinal infections, shellfish bed closure, recreation and aesthetic loss|
|Organic Enrichment* – BOD, COD, TOC, DO||Urban/agricultural runoff, landfills, septic fields||Dissolved oxygen depletion, Odors, Fish Kills|
|Toxic Pollutants – metals, organics||Urban/agricultural runoff, pesticides/herbicides, underground storage tanks, hazardous waste sites, landfills, illegal oil disposal, industrial discharges||Bioaccumulation in food chain, Toxicity to humans and other organisms|
|Salts – sodium chloride||Urban Runoff, snowmelt||Vehicular corrosion, contamination to drinking water, harmful to salt-intolerant plants|
*Note: BOD = Biochemical Oxygen Demand, COD = Chemical Oxygen Demand,
Construction site stormwater discharges are expected to contain pollutants that contribute to the following water impairments: Turbidity, Bio (Macroinvertebrate), TP (Total Phosphorus), and TN (Total Nitrogen). Any construction site where the nearest Water Quality Monitoring Station (WQMS) has any of the four above impairments will have to adhere to the state sedimentology requirements. (All offsite discharge will need to achieve an equivalent removal efficiency of 80 percent for suspended solids.)
Bureau of Water . Phone: (803) 898-4300 . Fax: (803) 898-3795 .