Perth Amboy, NJ Environmental Rules: Flood Elevation Requirements (2026)

Section 231-102.3 of the Perth Amboy City Code sets the Local Design Flood Elevation (LDFE) that governs how high buildings in the City of Perth Amboy, Middlesex County, New Jersey must be built above flooding. The elevation is set using the best available flood hazard data, the Flood Hazard Area Control Act minimum Statewide elevation requirements for lowest floors in A, Coastal A, and V zones, and ASCE 24 requirements for critical facilities, plus the freeboard the chapter specifies. Under the definitions, no project's LDFE can be lower than a permit-specified Flood Hazard Area Design Flood Elevation or a valid NJDEP Flood Hazard Area Verification Letter plus the freeboard required in ASCE 24 and the effective FEMA Base Flood Elevation.

For a delineated watercourse the elevation is that of the Best Available Flood Hazard Data Area plus one foot of freeboard, or the freeboard N.J.A.C. 7:13 describes. Where a watercourse is undelineated and has a contributory drainage area of 50 acres or more, the applicant must supply either an unexpired NJDEP Flood Hazard Area Verification plus one foot of freeboard and any additional freeboard required by ASCE 24, or a determination using Method 5 or Method 6 from N.J.A.C. 7:13 plus one foot of freeboard, sealed and submitted under Section 231-105.2-3. In Zone AO areas the LDFE is the highest adjacent grade plus the depth number specified plus one foot of freeboard; with no depth number it is three feet above the highest adjacent grade.

Critical facilities carry more. New and substantially improved Flood Design Class IV Critical Facilities must meet the higher of the 0.2% annual chance (500-year) flood elevation or the Flood Hazard Area Design Flood Elevation with an additional two feet of freeboard. Class III Critical Facilities in coastal high hazard areas use the same higher-of test with an additional one foot.

The LDFE then drives construction. Under § 231-801.2(A)(3), new construction and substantial improvement of any habitable building in flood hazard areas needs the lowest floor, including basement, and the attendant utilities elevated to or above the LDFE, in conformance with ASCE 24 Chapter 7 and confirmed by an Elevation Certificate. Non-residential structures either meet the same elevation or are designed so that the structure below the LDFE is floodproofed, with a Floodproofing Certificate. Where design flood elevations are not specified, § 231-103.7 authorizes the Floodplain Administrator to require the applicant to use Federal, State or other data, or a sealed engineering determination.