Dukes County, MA Environmental Rules: Flood Zones (2026)

Dukes County comprises six towns on Martha's Vineyard - Aquinnah, Chilmark, Edgartown, Oak Bluffs, Tisbury, West Tisbury - plus the unincorporated Town of Gosnold (Elizabeth Islands, including Cuttyhunk and Naushon). Five of the six Vineyard towns participate in the National Flood Insurance Program (NFIP); Chilmark is the only Island town that does not participate, which means residents there are not eligible for federally backed NFIP flood insurance and must seek private surplus-lines coverage. FEMA's countywide Flood Insurance Rate Maps for the Vineyard towns were issued in the 2014-2016 update cycle, with Edgartown's effective boundaries adopted by the town in 2016 and Oak Bluffs' expanded V/VE and AE zones effective in 2016. Mapped zones include VE (coastal high-hazard subject to 3-foot+ wave action along south-shore, Vineyard Sound, and Nantucket Sound coastlines), AE (1% annual chance flood with established Base Flood Elevation, including the great salt ponds such as Sengekontacket, Edgartown, Tisbury Great, Chilmark, and Menemsha Ponds), Coastal A / LiMWA (Limit of Moderate Wave Action), AO/AH (shallow flooding), and X (areas of reduced or minimal hazard). Floodplain administration is delegated to each town - typically the building commissioner, conservation agent, or designated floodplain administrator. The 9th Edition Massachusetts State Building Code 780 CMR R322 (residential) and Appendix G (commercial) governs construction in Special Flood Hazard Areas and incorporates ASCE 24-14 by reference, with the Design Flood Elevation set at the FEMA Base Flood Elevation plus 2 feet of freeboard statewide; in V Zones and Coastal A Zones the structure must be elevated on piles or columns with breakaway walls and flood-damage-resistant materials below the DFE. Independently, the Massachusetts Wetlands Protection Act (M.G.L. c. 131 sec. 40) and 310 CMR 10.00 prohibit any removal, fill, dredge, or alteration of coastal banks, beaches, dunes, barrier beaches, salt marshes, land under the ocean, or land subject to coastal storm flowage without a Notice of Intent and Order of Conditions from the local Conservation Commission, with appeal to MassDEP. Most Vineyard towns layer stricter local wetlands bylaws and 100-foot buffer zones on top of state law. Oak Bluffs has adopted a Coastal Floodplain Zoning Bylaw that prohibits new residential development and expansion of existing development in V, VE, and AO zones and requires a special permit for new development in A zones. The Martha's Vineyard Commission - the regional planning agency for Dukes County - prepared the 2021 Dukes County Multi-Jurisdictional Hazard Mitigation Plan (all seven towns) and runs the Coastal Resilience Initiative, which uses MC-FRM 2030/2050/2070 sea-level rise and storm-surge projections and has mapped 716 storm tide pathways across the Island; for every six inches of additional water level, between 213 and 778 acres of Vineyard land are inundated. Towns are updating their floodplain and wetlands bylaws using the model bylaws developed by Massachusetts state floodplain specialists, with a goal of bringing updated bylaws to 2026 annual town meetings. The 50% substantial improvement / substantial damage rule of the NFIP (44 CFR 60.3) applies in the five participating towns: when the cost of improvements or repairs to a structure within an SFHA reaches half its market value, the entire structure must be brought into full floodplain compliance.