A significant source of water quality impairment is stormwater runoff from impervious surfaces such as paved streets, parking lots and building rooftops during rainfall and snowmelt periods. This runoff carries pollutants such as oil, antifreeze, pesticides, fertilizer, heavy metals and pathogens that can contaminate streams, rivers, lakes and reservoirs.

The CWC administers three New York City-funded programs to help municipalities, businesses and property owners address and correct stormwater runoff problems which may contribute to degraded water quality, and to plan ways to avoid them in the future.