California
Buying Land in San Mateo County, California
San Mateo County runs from the dense San Francisco Peninsula suburbs to a narrow, sparsely developed Pacific coastline and a forested mountain spine -- and nearly all of its undeveloped, buildable rural land sits in those latter two zones, both shaped by a state law written specifically to keep them that way.
Two very different rural San Mateo Countys
San Mateo County's incorporated cities -- Redwood City, San Mateo, Daly City, and the rest of the Peninsula -- cover a small fraction of the county's total land area but hold nearly all its population. The unincorporated county is really two distinct rural landscapes: the narrow coastal strip locals call the Coastside, running from Devil's Slide near Pacifica down through Half Moon Bay's surrounding farmland to Pescadero and the San Mateo/Santa Cruz county line, and the forested Santa Cruz Mountains foothills inland, around communities like La Honda, Loma Mar, and Woodside's rural fringe. Both are shaped less by ordinary county zoning discretion than by state-level frameworks layered on top of it.
For a buyer, the practical difference matters: coastside land is agricultural and coastal-zone land first, meaning any development question runs through the LCP and potentially the Coastal Commission; mountain-foothill land is forested, often steep, and increasingly bordered by permanently protected open space, meaning access, fire risk, and easement questions dominate over pure zoning flexibility.
The Coastal Act and the Local Coastal Program
California's Coastal Act of 1976 established a state coastal zone along the entire California coastline, within which land use is governed either directly by the California Coastal Commission or, where a county has an approved Local Coastal Program, by the county itself under standards the Commission certified. San Mateo County has a certified LCP covering its coastside, meaning most day-to-day development review happens at the county level -- but certain permits remain appealable to the Coastal Commission, and the LCP's substantive standards (protecting agricultural land, public coastal access, environmentally sensitive habitat, and scenic resources) are considerably more restrictive than a typical inland zoning code.
A Coastal Development Permit is generally required for new construction, significant grading, or a change in land use within the coastal zone, on top of any standard county building permit. Timelines and requirements can run longer than an inland project of similar scope, so factor that into any purchase timeline for coastside land intended for near-term building.
Planned Agricultural District zoning on the Coastside
Much of the county's coastside farmland is zoned Planned Agricultural District (PAD) specifically through the LCP, a designation built to keep the area's prime agricultural soils in production rather than converting to residential estates. Historically, coastside agriculture has centered on Brussels sprouts, artichokes, and a substantial ornamental flower and nursery industry -- and PAD zoning's large minimum parcel sizes and restrictions on non-agricultural structures are the mechanism used to protect that industry's land base against fragmentation.
For a buyer evaluating coastside acreage, this means the county's own zoning code is likely to be more restrictive on subdivision and non-agricultural building than a generic 'rural residential' assumption would suggest. Confirm the exact PAD sub-designation and minimum parcel size on a target property directly with San Mateo County Planning before assuming any particular building or subdivision scenario is viable.
Water, wells, and open space in the foothills
Away from municipal water service, coastside and foothill parcels typically rely on a mix of small water districts (such as Coastside County Water District and Montara Water and Sanitary District, which serve parts of the Coastside) and private wells further inland or in less-served pockets. Septic systems are common outside the water-district service areas, permitted through San Mateo County Environmental Health.
In the Santa Cruz Mountains foothills, the Midpeninsula Regional Open Space District's extensive preserve holdings mean rural land here increasingly sits adjacent to permanently protected open space rather than adjacent to future subdivisions -- generally a durable amenity, but worth checking for any trail, access, or conservation easements already recorded against a specific parcel or its neighbors.
Who to Call Before Buying Land in San Mateo County
San Mateo County administers its certified Local Coastal Program directly for most coastside permits; the California Coastal Commission retains appeal jurisdiction over certain permit categories rather than handling day-to-day review itself.
Planning & Zoning
San Mateo County Planning and Building Department
Confirming a parcel's zoning designation (including PAD status), Local Coastal Program requirements, and Coastal Development Permit needs.
Septic / Onsite Wastewater
San Mateo County Environmental Health
Septic system permitting for parcels outside water/sewer district service areas.
Recorder / Clerk / Land Records
San Mateo County Assessor-County Clerk-Recorder
Recorded deed history, easements, and parcel records.
Other
California Coastal Commission
Appeal jurisdiction and state-level questions on coastal zone development beyond the certified Local Coastal Program.
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Get local guidanceTopics Specific to San Mateo County
Sources
- California Coastal Act — California Coastal Commission (accessed 2026-09)
- San Mateo County Local Coastal Program — San Mateo County, CA Government (accessed 2026-09)
- Alquist-Priolo Earthquake Fault Zoning Act — California Geological Survey (accessed 2026-09)
- Midpeninsula Regional Open Space District — Midpeninsula Regional Open Space District (accessed 2026-09)
- California Williamson Act Program — California Department of Conservation (accessed 2026-09)
Last reviewed 2026-09