St. Clair County, IL Environmental Rules: Flood Zones (2026)

Under Section 13-1-5 of the County Floodplain Code, no person, firm, corporation, or governmental body may commence any development in the floodplain without first obtaining a development permit from the Zoning Director, who will not issue one unless the proposal meets the Code's requirements. 1 foot. Development in the floodway also needs a separate permit from the Illinois Department of Natural Resources Office of Water Resources. The Zoning Director compares the site's surveyed elevation to the base flood elevation to decide whether the parcel is actually inside the regulated floodplain, and will not issue any permit until every other required local, state, and federal permit is obtained.

Once issued, the permit must be posted in plain view from a public road for the duration of the work, and any approved fill must carry a sign listing the material types. A permit expires after six months if no work has started, and the Zoning Director may revoke it for false statements or for work done contrary to the approved plans; continuing work after revocation is unlawful until the permit is reissued. All permitted work is subject to inspection by the Zoning Director and, for fill projects, by the St. Clair County Health Department, and refusing entry to either is itself a violation of the Code.