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

Section 174-8.9(B) ties the district boundaries to the 100-year base flood elevations shown on the Worcester County Flood Insurance Rate Map dated July 16, 2014. Where the map shows a Zone A with no FEMA base flood elevation or floodway data, subsection F directs the Building Department to obtain, review and reasonably utilize base flood elevation and floodway data from a federal, state or other source. That data becomes the criteria for requiring new construction, substantial improvements and other development to elevate residential structures to or above base flood level, to floodproof or elevate nonresidential structures to or above base flood level, and to prohibit encroachments in floodways.

Larger projects carry their own burden. Under subsection G(2)(a), a proponent of subdivisions or other developments greater than 50 lots or five acres, whichever is less, must provide technical data to determine base flood elevations for each developable parcel shown on the design plans. If the Town itself acquires data that changes the base flood elevation in a FEMA mapped Special Flood Hazard Area, subsection J requires it to notify FEMA within six months by submitting the supporting technical or scientific data to the NFIP State Coordinator at the Massachusetts Department of Conservation and Recreation and to the NFIP Program Specialist at FEMA Region 1.

Elevation also drives record keeping. Chapter 19, § 19-3, appoints the Select Board to maintain for public inspection, and to furnish on request, a record of elevations, in relation to mean sea level, of the lowest floor, including basement, of all new or substantially improved structures in the special flood hazard areas. If the lowest floor is below grade on one or more sides, the elevation of the floor immediately above must also be recorded.

When the State Building Code Appeals Board hears a variance, subsection K requires the Town to request a copy of that part of the hearing and to send the owner a letter, signed by a community official, stating that a variance to build below the base flood level will result in increased flood insurance premium rates, up to amounts as high as $25 to $100 of insurance coverage, and increases risks to life and property.