Marin County flood zones: who's paying more than the map requires

We analyzed every parcel touching a FEMA flood zone in Marin County — 18,888 of them — against current flood maps and USGS LiDAR ground elevations. Two groups stand out.

603 properties are mapped OUTSIDE the high-risk zone

These parcels sit outside the Special Flood Hazard Area on today's map — many moved out by levee accreditations and FEMA map revisions. Flood insurance is not federally required for them, yet owners with stale lender determinations may still be paying. If your address is one of them, the fix is paperwork: the current determination, documented for your lender.

1,844 flood-zone parcels measure ABOVE the flood elevation

These are inside the mapped zone, but LiDAR shows their ground at least a foot above the governing Base Flood Elevation — the profile of a FEMA Letter of Map Amendment candidate (a no-fee process that ends the insurance requirement; see our LOMA guide). Another 649 parcels measure within a foot — close enough that a field survey could go either way.

Counts are from our analysis of FEMA National Flood Hazard Layer polygons, county parcel data, and USGS 3DEP LiDAR (Marin County, 2026). Parcel-level screening, not a survey; individual results require the property-specific analysis in our reports.