Stormwater is defined by US EPA as the runoff generated when precipitation from rain and snowmelt events flows over land or impervious surfaces without percolating into the ground. Stormwater is often considered a nuisance because it mobilizes pollutants such as motor oil and trash. In most cases, stormwater flows directly to water bodies through sewer systems, contributing a major source of pollution to rivers, lakes, and the ocean. Stormwater discharges in California are regulated through National Pollutant Discharge Elimination System (NPDES) permits. However, stormwater may also act as a resource and recharge to groundwater when properly managed. More information on the state's Storm Water Program is available here



The California Stormwater Quality Association (CASQA) is a professional member association that advances sustainable stormwater management protective of California water resources. CASQA is a valued partner of the Roundtable of Regions. More information can be found here.