POLLUTANTS IN URBAN VS. NON-URBAN STORMWATER RUNOFF
One of the most comprehensive urban vs. non-urban stormwater study was conducted by the U.S. EPA’s National Urban Runoff Program (NURP) between 1978 and 1983, covered 2,300 storm events, and compared stormwater quality between three types of urban land uses (residential, mixed-use, and commercial) and non-urban land use. While the results from the NURP study indicate that no significant difference exists between data collected from different urban land use categories, there is a significant difference between urban and non-urban data. The high concentrations of nitrogen and phosphorus in residential areas come from fertilizer, car exhaust, soil erosion, animal waste, and leaking septic systems. Metals result from automobiles, bridges, atmospheric deposition, industrial activities, soil erosion, corroding metal surfaces, and combustion.