California unincorporated profile
Outside the boundaries of incorporated cities and towns, the Solano County government is the planning and permitting lead agency. That means county zoning, county building codes, and county environmental review apply directly — without a separate city layer. The county rules most likely to catch a project applicant off guard are listed below.
These Solano County rules apply directly to projects in unincorporated areas of the county, with no city-level overlay.
A newly updated airport land use compatibility plan for Travis Air Force Base includes a new low-altitude maneuvering zone that restricts building types and heights in surrounding areas — a constraint that wasn't present under the prior plan and that some Fairfield and Suisun City projects now need to address.
The county's Board of Supervisors stopped accepting new Williamson Act applications — existing contracted land retains its protections, but new parcels can no longer enroll, which affects agricultural land transactions differently than in most California counties.
Northeastern Solano, including areas near Rio Vista and Birds Landing, falls within the Sacramento-San Joaquin Delta Primary Zone, where the Delta Protection Commission imposes severe development restrictions on top of what county zoning alone would require.
Which air district rules and which stormwater permit applies depends entirely on where in the county the project sits — southern and northern Solano are governed by different agencies with different thresholds, and the rules are not the same across the county.
A regional conservation plan has been in development for more than two decades but has not yet been adopted, and the county's Board of Supervisors declined to participate — leaving county projects without a streamlined species permit process while neighboring jurisdictions' projects benefit from one.
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Screen an addressSource: Headlands Environmental — environmental site screening for California. Rules summarized from publicly available county codes and planning documents; project review counts indexed from the State Clearinghouse. For authoritative requirements, consult Solano County directly.