San Mateo County, CA Environmental Rules: Coastal Development (2026)

Under the California Coastal Act of 1976, San Mateo County was certified to issue its own CDPs via its Local Coastal Program (LCP), originally certified in 1981 and amended since. The Coastal Zone in San Mateo County extends from Devil's Slide in the north through Pacifica (except where Pacifica has its own LCP), Montara, Moss Beach, Princeton, El Granada, unincorporated Half Moon Bay fringes, San Gregorio, Pescadero, and Año Nuevo. Most new development, land divisions, change of use, and many exterior modifications in the Coastal Zone require a CDP. Categorical exclusions apply for certain minor improvements, repair/maintenance, and some single-family additions in non-appealable areas. Appealable-area projects (within 300 ft of the mean high tide line, in sensitive habitat, on agricultural land, or in rural areas) can be appealed to the California Coastal Commission after County action. LCP policies require: 100 ft ESHA buffers around riparian, wetland, and sensitive species habitat (reduced to 50 ft on case-by-case basis); public shoreline access easements for most waterfront projects; agricultural protection (preserve Prime Ag Land, ag cluster subdivisions); view protection along scenic coastal corridors; sea-level-rise adaptation and bluff retreat setbacks. Coastal bluff development must include geotechnical and coastal engineering review. Seawalls and shoreline armoring face strict Coastal Act §30235 limits.