Mason County, WA Environmental Rules: Boat Dock Permits (2026)

Mason County Code § 17.50.320, in the Shoreline Master Program, governs permits for docks, floats, mooring buoys, boat lifts, and covered moorage anywhere within the county's shoreline jurisdiction, including Hood Canal, Puget Sound, and shoreline lakes. Subsection (a)(13) limits new docks to water-dependent uses or public access, but specifically treats a dock built to serve a single-family residence as a qualifying water-dependent use. Subsection (b)(2)(B) caps ownership at one dock per waterfront lot, a limit that does not apply to public recreational docks. Dimensional standards differ by water body: a single-use freshwater dock cannot exceed sixty feet in length measured from the ordinary high water mark, while a single-use saltwater dock is capped at one hundred twenty feet, or whatever shorter distance reaches seven feet of water depth at mean lower low water, unless the Washington Department of Fish and Wildlife's hydraulic project approval or a Department of Natural Resources use authorization requires otherwise.

Joint-use and community docks get longer allowances under Tables 17.50.320-A and -B, and the county favors shared docks, requiring applicants to first show they contacted neighboring owners about sharing an existing dock before permitting a new single-use structure. All overwater structures must use functional grating, avoid treated wood components that contact the water, and stay a minimum of five feet from side property lines except for joint-use facilities. Applicants apply through Mason County Community Development's shoreline substantial development or exemption process, with the Washington Department of Ecology reviewing permits before they take effect.