Urban Stormwater Runoff Water Quality Issues

Abstract Urban stormwater runoff contains heavy metals including copper, lead, and zinc; organics such as pesticides, PAHs, and unidentified compounds; and nutrients (nitrogen and phosphorus) in concentrations that are a threat to cause water quality problems in the waters receiving the runoff. In 1990, the U.S. EPA adopted an urban stormwater runoff water quality management program that requires that municipalities control pollution of receiving waters for runoff to the maximum extent practicable using best management practices (BMPs) and, through a BMP ratcheting‐down process, ultimately control violations of water quality standards in the runoff. This regulatory program has several significant problems, including the high cost (dollars/person/day) of treating urban stormwater runoff to control water quality standards violations and the general ineffectiveness of conventional BMPs for contaminant control. Further, heavy metals and some other potential pollutants in urban stormwater runoff are largely in nontoxic, unavailable forms. Urban stormwater runoff water quality managers need to conduct studies to determine the constituents in stormwater runoff that cause significant pollution of the receiving waters. Those constituents that are causing significant water quality use‐impairments can potentially be controlled through source control. Also, wet weather water quality standards need to be developed to regulate urban stormwater runoff water quality impacts.