McLean County, IL Environmental Rules: Boat Dock Permits (2026)

Section 350-41F governs preventing increased flood heights within any floodway or undelineated floodplain in the county, and Section 350-41F(1)(d) lists minor boat docks among the specific activities the County treats as automatically meeting that no-increase standard, provided the dock satisfies the ten conditions of the Illinois Department of Natural Resources' Office of Water Resources Statewide Permit Number 5. Those conditions require the dock not extend more than 50 feet into the waterway and no more than one-quarter of the waterway's width, and not extend beyond navigational limits set by IDNR and the Army Corps of Engineers; the dock cannot exceed 10 feet in width; an L-shaped or T-shaped dock's shoreline-parallel portion cannot exceed 50% of the owner's shoreline frontage or 50 feet; the dock must be aligned so it does not cross the projected extension of property lines or come within 10 feet of that projected line; dock posts must carry reflective markers; the dock must be securely anchored against high wind or water; metal drums used for buoyancy must be filled with flotation foam and cannot have previously held pesticides, herbicides or other toxic chemicals; the permit does not cover related activity like shore protection or fill; nonfloating docks must be built to minimize flow obstruction; and the permittee must agree to make future modifications the IDNR or Corps requires.

A dock that cannot meet all ten conditions falls outside this minor-activity pathway and instead needs a full floodplain development permit reviewed under Section 350-41E by the Director of Building and Zoning.