A federal study of back-bay flood protection options for St. Augustine may not result in a recommended construction project after the alternatives reviewed failed to meet the U.S. Army Corps of Engineers’ cost-benefit requirements. During a May 11 special meeting, the St. Augustine City Commission received an update on the Army Corps Back Bay Coastal Storm Risk Management Feasibility Study.
The study was originally launched as a three-year, citywide federal feasibility study to investigate coastal storm impacts in St. Augustine and evaluate economically viable and environmentally sound ways to reduce coastal storm risk. The study to place between 2023–2026, with early phases focused on data collection, analysis, modeling and community outreach, followed by development, adoption and a final study. The feasibility study itself was funded as a $3 million effort, with the city using $1.5 million in American Rescue Plan Act funds and the Army Corps contributing $1.5 million.
The study has reached the National Economic Development Plan stage. At that point, all reviewed design alternatives came back with a benefit-cost ratio of less than one. Under the Army Corps process, that has led to a current recommendation of “no action.” The finding does not mean flooding is no longer a concern. It means the alternatives reviewed through this federal process did not meet the economic threshold required for the Army Corps to recommend moving forward.
The Back Bay study was created to evaluate ways to reduce flooding from coastal storms, extreme high tides and projected sea-level rise. Earlier city materials said the study was intended to help reduce flood damages affecting residents, businesses, historic and culturally significant resources, critical infrastructure and ecosystems.
Potential options reviewed through the study process included structural, non-structural and nature-based strategies. Those could include seawalls, tidal gates, revetments, levees, drainage improvements, building elevation, relocation, buyouts, living shorelines and oyster reefs.
The federal review depends heavily on benefit-cost analysis. In practical terms, a ratio below one means the projected return is less than one dollar for every dollar invested.
That does not prevent the city from pursuing local flood mitigation work. St. Augustine is already moving forward with several resilience-related projects, including the Avenida Menendez seawall, Lake Maria Sanchez stormwater project, South Davis Shores stormwater improvements, South Whitney and West King flood mitigation, Inlet Drive shoreline resiliency and citywide tide check valves.
The study may still be useful to the city. Information gathered through the process, including data collection, analysis, modeling and public outreach, could help shape future local projects, support grant applications or identify smaller-scale options that could be pursued outside the Army Corps process.
The update also highlights a challenge for historic coastal cities. Federal cost-benefit formulas may not fully capture the value of protecting historic districts, public infrastructure, tourism corridors, neighborhoods and cultural resources from repeated flooding.
For now, the current recommendation is no action under the federal study. The city’s local flood mitigation work, however, is continuing through separate capital projects.
Residents with questions about city stormwater and resilience projects may contact the St. Augustine Public Works Department at 904-825-1040 or Stormwater@CityStAug.com.
