Chelsea, MA Environmental Rules: Flood Elevation Requirements (2026)

Chapter 34, Section 34-184 establishes the Floodplain Overlay District (FOD) as an overlay covering all special flood hazard areas designated zone A, AE, AH, AO, A99, V, or VE on the county Flood Insurance Rate Map issued by FEMA under the National Flood Insurance Program. The applicable panels for Chelsea are numbers 25025C0017J, 25025C0018J, and 25025C0019J, dated March 16, 2016, and the district's exact boundaries follow the 100-year base flood elevations shown on those panels, cross-referenced against the county Flood Insurance Study (FIS) report of the same date.

Both the FIRM and FIS are incorporated by reference and kept on file with the city clerk, planning board, building official, and conservation commission. For unnumbered A zones, the code requires base flood elevation data to be submitted whenever a subdivision proposal or other development involves more than 50 lots or five acres, whichever is smaller, so the developer (not the city) generally bears the cost of establishing the exact elevation. In numbered A and AE zones without a designated floodway, the best available federal, state or local floodway data is used to bar encroachments that would raise flood levels during a base flood event.

000), and any variance from those state standards can only be granted through the state's own variance procedures, not the city's. Zone A applicants without FIRM-listed base flood elevation data must have that data reviewed by the board of health and the building inspector before any elevation or flood-proofing determination is made.