CS33C - Concurrent Session 33C: Florida's New Dam System Rules

Abstract Description: In 2024, the Florida Dam Safety Program (FDSP) made progress with the implementation of enhanced criteria for permitting the construction of new dams and alteration of existing dams. These new criteria comply with 33 U.S.C. § 467f, "National dam safety program," which mandates that each state dam safety program “must be working toward” meeting specified federal criteria.

One of Florida’s key updates addresses the need to identify “the maximum area that could be flooded if the dam failed” (33 U.S.C. § 467f(e)(2)(A)(xi)(II)). As of June 28, 2024, applicants are required to determine the downstream hazard potential for each dam by estimating the inundation area in the event of failure or mis-operation. Dams with an obvious or probable low hazard potential (LHP) classification, as defined in Federal Guidelines for Dam Safety: Hazard Potential Classification System for Dams (Federal Emergency Management Agency [FEMA], April 2004) may use simple evaluation methods to evaluate the inundation area. Modeling for suspected high hazard potential (HHP) and significant hazard potential (SHP) dams must be performed using hydrologic-hydrodynamic modeling software with two-dimensional unsteady state flow capability (preferably HEC-RAS 2D, Version 6) or equivalent software. Each inundation report, including inundation and evacuation maps for an emergency action plan (EAP), must meet the Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA, July 2013).

Another fundamental new criterion requires permit applicants to develop an EAP if the proposed activity is for an HHP or SHP dam. This meets the requirement to have a “system of emergency procedures to be used if a dam fails or if the failure of a dam is imminent” (33 U.S.C. § 467f(e)(2)(A)(x)). Florida requires an EAP to include six basic elements, but a specific format for plans is not mandated. This flexibility allows dam owners with existing EAPs to meet the requirement with minimal plan revision. In addition, FDSP’s Emergency Action Plan for Florida Dams and accompanying Emergency Action Plan Template for Florida Dams Instruction Manual (Florida Department of Environmental Protection, January 2023) are available for all dam owners to help facilitate EAP development, provide consistency and reduce costs.
Additional updated criteria require dam owners to provide: 1) dam parameter information for the state database (and, by extension, the National Inventory of Dams), 2) financial capability for perpetual operation and maintenance, 3) nutrient reduction where necessary, and 4) the current condition for each existing SHP and HHP dam.