The California Coastal Act requires the protection and restoration of marine and coastal resources, including the quality of all coastal waters (see California Coastal Act Policies Most Relevant to Water Quality and Management of Stormwater Runoff). Polluted stormwater runoff, also known as nonpoint source (NPS) pollution, is a leading cause of harmful impacts to the coastal environment. 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 the coastal environment requires not only minimizing the pollutants carried in stormwater runoff but also minimizing increases in the runoff volume and flow rate resulting from development projects. To accomplish this, for over two decades the Coastal Commission’s Water Quality Program staff has recommended that development projects give precedence to a Low Impact Development (LID) approach to stormwater management that aims to replicate the site’s natural hydrologic balance. 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 staff works to integrate effective NPS pollution prevention measures and LID strategies into coastal development projects and local governments’ land use planning documents, in accordance with Coastal Act requirements.

Water Quality Program staff also provides educational resources and technical assistance to address development activities that may adversely impact coastal resources by generating polluted runoff and/or increased stormwater runoff flows.