Lower Merion, PA Environmental Rules: Flood Elevation Requirements (2026)

Zoning Code § 155-2.1 defines BASE FLOOD ELEVATION simply as "the 100-year flood elevation," tied to the base flood itself, defined as the flood having a one-percent annual chance of being equaled or exceeded. Within the Schuylkill River Floodway Fringe, § 155-7.3H(4) requires sewer, water, and electric lines to be floodproofed to a height of 24 inches above the base flood level, certified by a Pennsylvania-registered professional engineer or architect and recorded with the Director of Building and Planning. Section 155-7.3H(5) requires that any permitted structure be built with all portions of all rooms, including basements, at least 24 inches above the base flood level, that two-foot freeboard margin above FEMA's minimum.

The only carve-out is for nonresidential structures in the Light Industrial District, which may sit at or above the base flood level itself, with their utility lines floodproofed to that lower elevation instead of the 24-inch standard. Separately, § 155-7.3B(2) requires anyone whose project would raise the base flood elevation to submit technical data to FEMA for a Letter of Map Revision, or a Conditional Letter of Map Revision if not yet built, no later than six months after the work that changed it, and a rise of more than one foot in Zones A1-30 or AE without a designated floodway triggers the same requirement.

A Zoning Officer permit is also required before any such map change takes effect, and the Township Manager submits the required annual National Flood Insurance Program report to FEMA under § 155-7.3J.