Lewis County, WA Fence Regulations: Retaining Walls (2026)

60 LCC), governs retaining walls that sit within a public right-of-way in unincorporated Lewis County. The section requires review by the county engineer and mandates that the wall be designed, signed, and stamped by a registered engineer licensed in the state of Washington. The plans must then be submitted by the applicant for approval by both the county engineer and the building official, meaning the retaining wall goes through Public Works and Community Development before construction can begin. The code also gives the county discretion to demand more due diligence on unstable ground: where soil conditions are questionable, the county may require a soils investigation and report prepared by a geotechnical engineer before it will sign off.

This section sits inside the same road-standards chapter that governs sight distance, guardrails, and drainage along county roads, so it applies specifically to walls that support or abut the right-of-way rather than to every retaining wall on private property elsewhere on a rural lot. Property owners planning a wall near a county road frontage, driveway approach, or right-of-way edge should contact the Lewis County Department of Public Works engineering section before pouring footings, since the review is tied to the road standards enforced under Title 12 LCC and coordinated with the Community Development building section.