Cowlitz County, WA Environmental Rules: Flood Zones (2026)

25 (Floodplain Management) applies to all special flood hazard areas within the unincorporated area of the county, as identified on FIRMs from the Flood Insurance Study for Cowlitz County dated December 16, 2015. 060(A)(1), a floodplain permit must be obtained from the Floodplain Administrator, housed in the Department of Building and Planning, before any construction or development activity, including fill placement, begins within a special flood hazard area; the permit application must include an elevation certificate showing the lowest floor elevation in relation to mean sea level.

080(A) sets general standards for every structure built in these areas: new construction and substantial improvements, including manufactured homes, must be anchored to prevent flotation, collapse, or lateral movement from hydrodynamic and hydrostatic loads, built with flood-resistant materials and methods, and have electrical, heating, plumbing, and air-conditioning equipment elevated at least one foot above the base flood elevation. Water wells must sit on high ground outside the floodway, and new or replacement sewage systems must be designed to keep floodwater out. 080(A)(5)(d). Watercourse alterations require advance notice to the Washington Department of Ecology and adjoining communities. 02 CCC.