Stoimwater and Sediment 



BOD loadings originate fk)m older, highly impervious residential areas having outdated 

 combined sewer overflows, failed septic systems, and large pet populations. 



Oil and Grease 



Of the range of hydrocarbon compound constituents of oil and grease, several are toxic 

 to aquatic and marine life at low concentrations. Primary sources of hydrocarbons in urban 

 nmoff are atmospheric deposition, leakage of crankcase oil and other lubricants from 

 automobiles, disposal of used crankcase oil, and spillage at storage and transfer points. 

 Hydrocarbon levels are highest in runoff from parking lots, roads, and service stations. 

 Because hydrocarbons have a strong affinity for sediment, much of the hydrocarbon 

 loading to runoff eventually adsorbs to sediment particles and setties out, where it 

 accumulates in bottom sediments. Hydrocarbon persistence is a major concern. Not only 

 have hydrocarbons been shown to persist in freshwater and estuarine sediments for long 

 periods of time, but chronic adverse impacts on benthic life have been documented 

 (Whipple et al., 1979; Whipple et al., 1981; Tanacredi and Stainken, 1981). 



Trace Metals 



Sampling research conducted as pan of the Nationwide Urban Runoff Program revealed 

 detectable levels of a range of metals in urban runoff: arsenic, beryllium, cadmium, 

 chromium, copper, cyanide, mercury, nickel, lead, selenium, thallium, and zinc (DDN, 

 1982). Of these, cadmium was found in many samples, and lead, copper, and zinc were 

 found in most samples, and occasionally at levels an order of magnitude greater than EPA's 

 recommended criteria levels for aquatic life. (Trace metal inputs are geographically 

 variable; estimated concentrations for Narragansett Bay are discussed below.) 



Toxic Chemicals 



"Priority pollutant" scans were conducted during the NURP studies to determine the 

 extent to which more than 120 toxic or carcinogenic chemicals or compounds could be 

 associated with runoff. Because the mnoff scans were primarily conducted in suburban 

 residential areas, sources of toxic pollutants were limited to illegally or improperly disposed 

 household wastes, such as waste oil, paint thinners, preservatives, and pesticides. Priority 

 pollutants detected in a Washington, D.C. area scan included 10 pesticides (at levels near 

 the limits of detection), bis(2-ethylhexyl) phthalate (a plasticizer), and several phenols and 

 creosols associated with wood preservatives. Runoff samples collected from existing or 

 abandoned industrial areas have revealed other toxicants. 



Chlorides 



Chlorides applied to remove ice and snow from roads, parking lots and sidewalks, and 

 improperly stored road salts, are very frequently introduced into receiving waters. 

 Novomy and Jones (1986) reported snowmelt chloride levels exceeding several thousand 

 milligrams per liter, or approaching the salinity of major estuaries such as Chesapeake Bay. 

 Because of chloride's extreme solubility, virtually all chloride applied to surface areas is 

 delivered to surface or ground waters (Pitt, 1985). Substantial chloride levels may have 

 been found to be toxic to freshwater and inshore estuarine species, which are adapted to 

 fairly narrow salinity ranges. 



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