The California Coastal Act requires the protection and restoration of marine and coastal water resources, including water quality (see California Coastal Act Policies Relevant to the Prevention of Polluted Runoff). Polluted runoff, also known as nonpoint source (NPS) pollution, is a leading cause of harmful impacts to coastal water resources. As stormwater runoff flows across the land, it picks up natural and human-made pollutants originating from many diffuse sources, and may transport these pollutants into coastal waters, including the ocean, rivers, wetlands, lakes, and groundwater.

Protection of coastal water resources requires not only minimizing pollutants carried in runoff, but also minimizing changes in a site’s natural runoff flow regime. Because of the dispersed nature of NPS pollution and the cumulative impact of changes in runoff flows within a watershed, it is critical to manage land use both regionally and on a site-specific level.

The Coastal Commission’s Water Quality Program works to integrate effective NPS water quality protection measures into coastal development projects and local governments’ land use planning documents, in accordance with Coastal Act requirements.

In coordination with other agencies, Water Quality Program staff also provides educational and technical assistance to address development activities that may impact coastal resources by generating polluted runoff or changes in runoff flows.

The Coastal Commission also works in partnership with the State Water Resources Control Board as the lead agencies for implementing California's NPS Program, providing a coordinated statewide approach to managing NPS pollution.