Seattle, WA Environmental Rules: Sea Wall & Bulkhead (2026)

Seattle's Shoreline Master Program (SMP), codified at SMC 23.60A, regulates all development within the city's shoreline environments including seawalls, bulkheads, and other shoreline stabilization structures. A seawall or bulkhead is defined as a wall or structure erected at or near the ordinary high water mark that retains land or protects it from wave action. New seawall construction, substantial repairs, and replacement typically require a Shoreline Substantial Development Permit from SDCI, which involves environmental review under the State Environmental Policy Act (SEPA). Routine maintenance and minor repairs may qualify for a shoreline exemption. The SMP prioritizes soft-shore stabilization methods over hard armoring (seawalls/bulkheads) where feasible, consistent with the Washington Department of Ecology's shoreline guidelines. Property owners are responsible for maintaining their seawalls in safe condition and must obtain permits before beginning repair or replacement work. The Seattle Seawall Project, completed in 2017, rebuilt the city's 3,700-foot central waterfront seawall, incorporating earthquake resistance and salmon habitat features. Private seawall owners must comply with federal permits (Army Corps of Engineers Section 10/404) in addition to local permits for any work below the ordinary high water mark.