King County, WA Environmental Rules: Boat Dock Permits (2026)
Key Facts
- Max dock area
- 480 sq ft (single home)
- Max length
- 150 ft (Lake WA/Sammamish)
- Residential lots
- one dock, generally
- New boat launch ramps
- banned outright
- Natural environment
- docks prohibited
Summary
Unincorporated King County limits shoreline docks to water-dependent uses, caps most residential lots to one dock or moorage facility, and bans new private boat launch ramps entirely.
Docks, piers, moorage piles or buoys, floats or launching facilities are allowed only for water dependent uses or for public access and shall be limited to the minimize size necessary to support the use. New private boat launch ramps are not allowed; ... Only one dock, pier, moorage pile or buoy, float or launching facility may be allowed for a single detached residential lot and only if the applicant demonstrates there is no feasible practical alternative.
Full Breakdown
King County Code Section 21A.25.180 governs docks, piers, moorage piles, buoys, floats and launching facilities in the shoreline jurisdiction of unincorporated King County. They are allowed only for water-dependent uses or public access, and new private boat launch ramps are banned outright. Most single-family lots get one dock or moorage facility, and only if no feasible practical alternative exists. Docks are barred entirely in the Natural shoreline environment. On freshwater lakes, new residential piers and docks face strict size limits: 480 square feet maximum surface coverage for a single dwelling, and up to 150 feet in length on Lake Washington or Lake Sammamish.
Violations & Fines
Building without a shoreline substantial development permit from King County DDES, or exceeding the size and length limits, risks a stop-work order, fines and removal of the unpermitted structure.
Frequently Asked Questions
Can I build a private boat launch ramp in unincorporated King County?
How big can a new residential dock be on a King County lake?
Does this rule cover docks in Seattle or Bellevue?
Sources & Official References
Other rules in King County
Compare King County to another location·View the Washington environmental rules overview
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