Document Available: Characterization of Used Oil in Stormwater Runoff in California

Runoff from urban areas has been identified as one of the leading sources of water quality impairment of the nation’s surface waters, having been associated with changes in flow, increased sedimentation, higher water temperature, lower dissolved oxygen, degradation of aquatic habitat structure, loss of fish and other aquatic populations, and decreased water quality. This runoff is the primary transport system moving pollutants from the landscape to wetlands, streams, lakes and coastal waters. Although the effects of runoff on specific waters vary and are often not fully assessed, pollutants carried by runoff are known to have potentially harmful effects on drinking water supplies, recreation, fisheries, and wildlife.

Among the pollutants in runoff are oil and oil byproducts, which are known to contain harmful constituents such as metals and polycylic aromatic hydrocarbons (PAHs). The extent by which these materials are polluting stormwater runoff and the ultimate receiving waters is largely unknown. In this report, the Office of Environmental Health Hazard Assessment (OEHHA) reviews stormwater monitoring data for the purpose of characterizing used oil pollution in stormwater runoff. Stormwater runoff refers to water transported through stormwater conveyance systems during and after storm events.