Washington County, MN Environmental Rules: Flood Zones (2026)

1). The chapter reaches only unincorporated townships; incorporated cities such as Stillwater, Oakdale, Cottage Grove, Woodbury and Forest Lake administer their own floodplain rules. 2, a permit from the Zoning Administrator is required before erecting, adding to, modifying, rehabilitating or altering any building or structure; before changing the use of a building, structure or land; before constructing a dam, fence or on-site septic system; before extending a nonconforming use; before repairing flood-, fire- or tornado-damaged structures; and before placing fill, excavating materials, or storing materials or equipment in the floodplain.

Every permitted development must use anchoring to prevent flotation, collapse or lateral movement, flood-resistant materials, and construction methods that minimize flood damage. 3 limits primary and conditional floodplain uses to those not already prohibited by the underlying zoning district. 1.