St. Clair County, IL Environmental Rules: Boat Dock Permits (2026)

No one may start dock construction or any other floodplain development in the unincorporated county without first getting a development permit from the Zoning Director (Floodplain Code Sec. 13-1-5). The application must include scaled site drawings with property lines, existing and proposed grade elevations, the location and dimensions of any structure, and a cost estimate from a licensed engineer, architect, or contractor. A standalone floodplain permit costs $25; if construction begins before the permit is issued, the fee jumps to $250 (Sec. 13-1-16), and permits bundled with a building permit are exempt from the separate fee.

Because a dock alters flood flow, Sec. 13-1-6(A) bars development that increases flood heights or velocity, but Sec. 13-1-6(A)(3) treats a minor boat dock as automatically meeting that standard if it satisfies the conditions of Illinois DNR/Office of Water Resources Statewide Permit No. 5, the same state authorization other minor waterway structures rely on under the same subsection (barge fleeting, aerial utility crossings, outfall structures). Separately, if the parcel carries the county's C-R Conservation-Recreation zoning district, Zoning Ordinance Sec. 40-4-92 lists 'Boat docks and marinas' among the uses that may be granted only through a Special Use Permit, which requires a Land Evaluation and Site Assessment unless the Zoning Administrator waives it in writing, plus a public hearing under Article XI Division V (Ord. No. 95-12, 05-30-95).