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s urbanization increases, so does the concentration of pavements, buildings and other impervious surfaces. These surfaces generate additional runoff and pollutants during rainstorms causing streambank erosion, as well as degenerating lakes and polluting sources of drinking water.

Increased runoff also deprives groundwater from being recharged, decreasing the amount of available drinking water in many communities. Recreational opportunities from lakes, streams and rivers decline from the impacts of urban runoff.

Commercial fishing productivity can decline in estuaries and bays thereby negatively impacting regional economies.

In response to environmental and economic impacts from stormwater runoff, U.S. federal law mandates that states control water pollution in runoff through the National Pollutant Discharge Elimination System (NPDES). Among many things, the law requires that states and localities implement best management practices (BMPs) to control non-point source pollution in runoff from development.

BMP’s can include storage, filtration and infiltration land development practices. Infiltration practices capture runoff and rely on infiltration through soils, vegetation, or aggregates for the reduction of pollutants. Detention ponds are a common BMP example used to hold, infiltrate, and release stormwater. Infiltration trenches are another that reduce stormwater runoff and pollution, and replenish groundwater. All of these BMPs provide some treatment and reduction of runoff pollutants.