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

110 governs where boat docks, floats, piers and launching ramps can go on wetland-adjacent shorelines. The baseline rule is a prohibition: these structures cannot be built in estuarine wetlands or Category I wetlands at all. 110, plus five specific standards. New floating docks, floats and piers on lakes are allowed only where the lake-fringe wetland vegetation is under sixteen feet wide, and the applicant must site the structure in a natural gap in that vegetation where one exists rather than cutting a new opening. No treated wood or other hazardous material may be used in construction, or placed in, over, or within one hundred feet of the water.

Public boat launches face an even tighter test: the county may only permit one in a lake-fringe wetland or buffer if there is no existing public access to that lake and no alternative location outside the wetland or buffer that could accommodate it, and any parking, restrooms or related facilities must sit outside the wetland and buffer, designed to keep untreated stormwater runoff from reaching the water. Existing, legally established docks, piers, floats and boat launches can be maintained without a new permit, but neither the width nor the length may be increased, and hazardous materials stay off-limits except through a county-approved Integrated Pest Management Plan or a demonstration the material poses no water-quality risk.

Replacement of a legally established structure is allowed on the same terms: no increase in length or width, and materials must meet the current standards for new construction. The section defines "floats" broadly to include floating docks, mooring buoys, navigational aids and swimming floats, so those are swept into the same permitting standard.