Lehigh County, PA Environmental Rules: Flood Elevation Requirements (2026)

Section 492.21 requires the flood elevation map used for a project to be based on the municipal Flood Insurance Rate Map (FIRM), falling back to estimated 100-year flood elevations or estimated flood-prone areas from the best available data where no FIRM covers the site. Building on that baseline, Section 492.25 caps how low a proposed street's finished elevation can sit relative to the Regulatory Flood Elevation: no more than one foot below it, with the LVPC empowered to demand street profiles and elevation data to verify compliance, and drainage openings must be sized to pass flood flows without worsening flood heights.

Sections 492.26 through 492.29 extend the same Regulatory Flood Elevation benchmark to infrastructure: sanitary sewer systems, whether public or private, must be floodproofed up to it; installing sewage disposal facilities that rely on soil absorption systems is flatly prohibited within designated flood plain areas under Section 492.27; water systems must likewise be flood-proofed up to that elevation; and all other public and private utilities, including gas and electric service, must be elevated or flood-proofed to the same benchmark. As with every SALDO provision, Section 121.1 confines this reach to municipalities that have not adopted their own subdivision ordinance, so the governing elevation standard for most Lehigh Valley parcels comes from the municipality's own floodplain management ordinance and FEMA-derived base flood elevation, not this county text.