St. Louis County, MO Environmental Rules: Boat Dock Permits (2026)

St. Louis County's Zoning Ordinance treats waterfront dock use as a permitted, by-right activity in two specific districts rather than leaving it to case-by-case approval. Section 1003.101, the "FP" Flood Plain District Regulations, lists "boat docks for other than commercial or industrial use" as its first permitted land use, alongside farming, golf courses, and wildlife propagation; the "FP" designation overlays flood-hazard portions of the county and exists, in the code's own words, to protect human life and health and to minimize expenditure of public money for costly flood control projects. Because the permitted-use language is limited to non-commercial and non-industrial docks, a marina or a commercial boat rental operation doesn't qualify for by-right treatment in the FP District.

Section 1003.103, the "PS" Park and Scenic District Regulations, goes further and lists "marinas, boat docks and ramps" as item 8 on its permitted-use table, alongside camping, boating, and fishing, without the FP District's non-commercial carve-out. A property owner whose land straddles both an underlying district and the FP overlay must still meet whichever district's minimum lot area and setback rules apply, and any dock or marina use not on either district's permitted list needs a Conditional Use Permit from the Planning Commission under Section 1003.181 before construction can begin.