Identifying the FFRMS floodplain.
24 C.F.R. § 55.7
in effectEffective: 2024-07-01(a) HUD or the responsible entity shall determine all compliance with the floodplain review requirements of this part based on the FFRMS floodplain.
(b) For a non-critical action, HUD or the responsible entity shall define the FFRMS floodplain using the following process:
(1) The climate-informed science approach (CISA) to identify the area having an elevated flood risk during the anticipated life of the project if data is available and actionable. Data is available and actionable for a particular project where:
(i) The data can be accessed via a tool, resource, or other process developed or identified by a Federal agency or agencies to define the floodplain using the CISA, and
(ii) HUD has adopted the particular tool, resource, or other process through a Federal Register publication for comment.
(2) If CISA data is not available or actionable but FEMA has defined the 0.2-percent-annual-chance floodplain, those areas that FEMA has designated as within the 0.2-percent-annual-chance floodplain; or
(3) If neither CISA data nor FEMA-mapped 0.2-percent-annual-chance floodplain data is available, those areas that result from adding an additional two feet to the base flood elevation as established by the effective FIRM or FIS or—if available—FEMA-provided interim or preliminary maps or studies or advisory base flood elevations.
(4) FFRMS floodplain determinations under paragraphs (b)(2) and (3) of this section shall be made using the information provided in the latest FEMA resources. Elevation determinations based on CISA data or an interim or preliminary FEMA map cannot be used as a basis for a lower elevation than the base flood elevation on the current FIRM or FIS.
(c) For a critical action, the FFRMS floodplain is either:
(1) Those areas designated as having an elevated flood risk identified by the climate-informed science approach (CISA)—as determined based on the criticality of the action—during the anticipated life of the project if the data is available and actionable, as available and actionable is described in paragraph (b)(1) of this section; or
(2) If CISA data as described above is not available or actionable, an area either within the 0.2-percent-annual-chance floodplain or within the area that results from adding an additional three feet to the base flood elevation. The larger floodplain and higher elevation must be applied where the 0.2-percent-annual-chance floodplain is mapped. If FEMA resources do not map the 0.2-percent-annual-chance floodplain, the FFRMS floodplain is the area that results from adding an additional three feet to the base flood elevation based on best available information.
(3) FFRMS floodplain determinations under paragraph (c)(2) of this section shall be made using the information provided in the latest FEMA resources.
(d) If CISA data is not available or actionable and if FEMA FIRMS, FIS, preliminary maps or advisory base flood elevations are unavailable or insufficiently detailed to determine base flood elevation, other Federal, Tribal, State, or local data shall be used as “best available information.” If best available information is based only on past flooding and does not consider future flood risk:
(1) For non-critical actions, the FFRMS floodplain includes those areas that result from adding an additional two feet to the base flood elevation based on best available information.
(2) For critical actions, the FFRMS floodplain includes those areas that result from adding an additional three feet to the base flood elevation based on best available information.
(e) When preparing an Environmental Impact Statement (EIS), an analysis of the best available, actionable climate science, where available and actionable data exists or can be generated in accordance with 42 U.S.C. 4336(b)(3), as determined by HUD or the responsible entity, must be performed to define the FFRMS floodplain. These sources may supplement the FIRM or Advisory Base Flood Elevation (ABFE) in order to better minimize impacts to projects or to elevate or floodproof structures above the risk adjusted floodplain. These sources may not be used as a basis for a lower elevation than otherwise required under this section.
(f)(1) Regardless of whether HUD has adopted a particular tool, resource, or other process to define the floodplain using CISA, as described in paragraphs (b)(1) and (c)(1) of this section, HUD or a responsible entity may voluntarily define the FFRMS floodplain utilizing CISA when:
(i) A State, Tribal, or local government formally adopts, through code or other formal adoption measures, a tool, resource, or other written standard developed or utilized by the State, Tribal, or local government that provides data or other methods to identify the FFRMS floodplain using CISA for a particular project; or
(ii) HUD publishes guidance identifying a particular tool, resource, or other process that may be used to define the floodplain using CISA, and the tool, resource, or other process identified in the HUD-published guidance contains the necessary data or information to define the floodplain for the project being considered.
(2)(i) The approach in this paragraph (f) may not be used as a basis for a lower elevation than the lowest of:
(A) The 0.2-percent-annual-chance floodplain elevation;
(B) The elevation that results from adding an additional two feet to the base flood elevation; or
(C) The elevation required by paragraph (b) or (c) of this section, if CISA data is available and actionable under paragraph (b)(1) or (c)(1).
(ii) Where HUD or a responsible entity voluntarily defines the FFRMS floodplain using the options in paragraph (f)(1)(i) or (ii) of this section, the criticality of the action must be considered when determining the appropriate elevation of the FFRMS floodplain.
Source: eCFRURL: https://www.ecfr.gov/api/versioner/v1/full/2024-07-01/title-24.xmlFetched: 7/26/2026