Petaluma, CA Environmental Rules: Flood Zones (2026)

Chapter 6 of the Petaluma Implementing Zoning Ordinance (IZO), current through Ordinance 2907 (September 8, 2025), regulates every parcel within the Area of Special Flood Hazard identified in the 1979 FEMA "Flood Insurance Study for the City of Petaluma" and its Flood Insurance Rate Maps, covering the Petaluma River Basin: the Petaluma River itself plus Washington, Lynch, Adobe, Capri, Corona and Kelly creeks and other tributaries (IZO §6.020, §6.030(DD)). Land inside that mapped area but outside the mapped channel is zoned Flood Plain-Combining (FP-C) under §6.040; the FP-C layer stacks on top of the underlying zoning district's rules rather than replacing them, and any permitted, accessory or conditional use there still needs a development permit.

Land inside the mapped Floodway itself is zoned FW under §6.050, and because floodway lands carry the highest velocity flood risk, the ordinance bars essentially all encroachment (fill, new construction, intensified uses, substantial improvements) except a short list of permitted uses (open-space farming and grazing without fences, circuses and carnivals with a zoning permit, native-vegetation modification approved by the Director) and conditional uses (public parks and athletic fields, docking and boat-launching facilities, above-ground utility lines including telecom facilities under PMC Chapter 14.44, and stream-channel or levee improvements), each requiring an engineer's certification that flood levels will not rise.

Before any of that work starts, §6.070(B) requires a development permit application to the Planning Director showing proposed elevations, floodproofing plans and any watercourse alteration, with a use permit layered on where one is needed under §24.060. The Community Development Department, through the Floodplain Administrator (the Planning Director or a designee), reviews every application, keeps elevation certifications on file for public inspection under §6.080, and must notify the California Department of Water Resources before any watercourse is altered or relocated. Boundary disputes over the mapped hazard area go to appeal under §24.090.