Port St. Lucie, FL Fence Regulations: Retaining Walls (2026)

Outside a mapped floodway, Port St. Lucie's Floodplain Management Regulations do not separately limit retaining wall height or design; the applicable floodway restriction is narrow but strict. Sec. 16(c) states that retaining walls, sidewalks, and driveways involving the placement of fill in a regulated floodway must meet the limitations of Sec. 12(d). That section bars any development, including site improvements and land-disturbing activity involving fill or regrading, in the regulatory floodway unless a floodway encroachment analysis required under Sec. 04(c)(1) demonstrates the work will not increase the base flood elevation at all, a no-rise standard with zero tolerance for elevation increase.

The same chapter separately singles out fences that could block floodwater passage in a regulated floodway, such as stockade or wire mesh fences, for the identical no-rise review under Sec. 16(b), and applies the same test to roads and watercourse crossings under Sec. 16(d). Because the encroachment analysis must satisfy the Floodplain Administrator, designated as the City Engineer under Sec. 02(a), a retaining wall proposed in a floodway effectively needs a certified hydraulic study before a floodplain development permit issues under Sec. 03. A retaining wall built in a floodway without that permit and analysis is treated the same as any other unpermitted floodplain development.