Stormwater is the water that runs off a land surface after a rain event. Because runoff after heavy rainfall can cause flood damage and contribute to water quality impairments, stormwater is carefully managed by local governments to minimize these negative impacts. The federal Clean Water Act regulates stormwater discharges through the National Pollutant Discharge Elimination System (NPDES). The NPDES is designed to reduce pollutant sources that discharge to receiving waters (e.g., lakes, rivers, ponds, bays, estuaries, oceans). Pollution sources regulated under the NPDES program fall into three categories: construction activity, industrial activity and Municipal Separate Storm Sewer Systems (MS4).

An MS4 is a system of conveyances such as stormdrains, pipes, guttering, ditches and catch basins that captures and directs stormwater, separate from the conveyances that direct municipal sewage.

Although the US Environmental Protection Agency (EPA) has ultimate authority for the NDPES program, in Florida the program is administered by the state Department of Environmental Protection (DEP). The DEP NPDES web page is here.