Stormwater
Federal requirements
In the United States, the Environmental Protection Agency (EPA) is charged with regulating stormwater
pursuant to the Clean Water Act (CWA).The goal of the CWA is to restore all “Waters of the United States” to their “fishable” and “swimmable” conditions. Point source discharges, which originate mostly from municipal wastewater (sewage) and industrial wastewater discharges, have been regulated since enactment of the CWA in 1972. Pollutant loadings from these sources are tightly controlled and limited. However, despite these controls, thousands of water bodies in the U.S. remain classified as “impaired,” meaning that they contain pollutants at levels higher than is considered safe by EPA for the intended beneficial use of the water. Much of this impairment is due to polluted runoff.
Under the CWA, point source discharges to “Waters of the United States” require National Pollution Discharge Elimination System (NPDES) permits. To address the nationwide problem of stormwater pollution, in 1987 Congress broadened the CWA definition of “point source” to include industrial stormwater discharges and municipal separate storm sewer systems (“MS4″). These facilities were required to obtain NPDES permits. This 1987 expansion was promulgated in two phases: Phase I and Phase II. Phase I required that all municipalities of 100,000 persons or more, industrial dischargers, and construction sites of 5 acres (20,000 m2) or more have NPDES permits for their stormwater discharges. Phase I permits were issued in much of the U.S. in 1991. Phase II required that all municipalities, industrial dischargers, construction sites of 1-acre (4,000 m2) or more, and other large property owners (such as school districts) have NPDES permits for their stormwater discharges. Phase II rules came into effect in 2003.
On May 16, 2008 the United States Environmental Protection Agency announced the issuance of a new Construction General Permit (CGP) to replace the permit that expires on July 1, 2008. This new permit has no substantive changes to the current Construction General Permit save the extension of the current conditions through July 1, 2010.
In 2009, the EPA launched the website Watershed central to allow concerned public to develop plans to protect local watersheds and combat stormwater pollution.
State and local requirements
The EPA has authorized 45 states to issue NPDES permits. In addition to implementing the NPDES requirements, many states and local governments have enacted their own stormwater management laws and ordinances, and some have published stormwater treatment design manuals. Some of these state and local requirements have expanded coverage beyond the federal requirements. For example, the State of Maryland requires erosion controls and sediment controls on construction sites of 5,000 sq ft (460 m2) or more.
Nonpoint source pollution management
Agricultural runoff (except for concentrated animal feeding operations, or “CAFO”) is considered by the CWA to be nonpoint source pollution. It is not included in the CWA definition of “point source” and therefore not subject to NPDES permit requirements. The 1987 CWA amendments established a non-regulatory program at EPA for nonpoint source pollution management consisting of research and demonstration projects. Related programs are conducted by the Natural Resources Conservation Service (NRCS) in the U.S. Department of Agriculture.