Renton, WA Environmental Rules: Boat Dock Permits (2026)

Any new, expanded, or modified pier or dock in Renton's shoreline jurisdiction falls under RMC 4-3-090.E.7, Piers and Docks, part of the city's Shoreline Master Program. The code puts the burden on the applicant: "The responsibility rests on the applicant to affirmatively demonstrate the need for the proposed pier or dock in his/her application for a permit, except for a dock accessory to a single family residence on an existing lot." All piers and docks must avoid or minimize ecological harm so there is no net loss of shoreline function, and expansion of an existing dock is preferred over building a new one.

For a single-family dock, the length is capped at the minimum needed for moorage, "a maximum of one ell and two (2) fingers," with an absolute maximum of 80 feet from the ordinary high water mark (OHWM). Ells and fingers are limited to 26 feet, and floats to 20 feet. Dock and pier width is capped at 4 feet for single-family use, with ells and floats at 6 feet and fingers at 2 feet. Mooring piles are limited to two piles, up to 12 inches in diameter, installed within 24 feet of the dock and out of the nearshore area. Side setbacks require that "no portion of a pier or dock may lie closer than 5 ft. to an adjacent property line and may not interfere with navigation." Joint use docks serving more than four residences, or shared docks required for subdivisions of more than two single-family units, are subject to separate marina or shared-moorage standards. Materials treated with creosote or pentachlorophenol are prohibited, and new boat houses are not allowed.