North Hempstead, NY Environmental Rules: Flood Zones (2026)

Chapter 21, Floodplain Management Regulations, applies to all areas of special flood hazard within Town jurisdiction, as mapped on FEMA's Flood Insurance Rate Map panels for Community No. 360482 (effective September 11, 2009) and the 2009 Flood Insurance Study for Nassau County. The Commissioner of the Building Department serves as Local Administrator and grants or denies floodplain development permits. Under § 21-12, a floodplain development permit is required for all construction and other development in a mapped special flood hazard area, and undertaking development without one is unlawful.

Applications must include scaled plans showing existing and proposed structures, fill, storage and drainage, and must be accompanied by a fee set in the Town's Fee Schedule; the Local Administrator can require a deposit of up to $500 to cover extra review and inspection costs. Depending on the flood zone, applicants must supply proposed lowest-floor elevations, floodproofing certifications from a licensed engineer or architect, and, for Zone A subdivisions larger than 50 lots or five acres without published base flood elevation data, engineering studies to establish it.

Anyone proposing to alter or relocate a watercourse must submit computations proving the new channel carries at least as much water as the original segment. On streams without a mapped regulatory floodway, new construction or fill is barred unless the applicant proves the cumulative effect of development will not raise the base flood's water surface more than one foot, or the Town obtains a FEMA map revision. Any fill placed below the base flood elevation must be offset by an equal volume of excavation that drains freely to the watercourse.