Most residential docks never see this rule. The ones that do are the multi-well, covered, lift-loaded structures that feel like a small marina. Appendix B draws the line at 3,000 square feet of water space.
What is counted
Ameren counts the dock, the water inside the slips, lifts and other structures attached to the dock, ramps, and breakwaters. If you have two docks, the areas are added together. Ameren, not the owner’s tape measure, makes the final call. A pier allowed to cantilever over a seawall is assessed at the same rate as a dock.
What changes when you cross it
Two things, both in Appendix B:
- Plans, specifications, and calculations for a dock over 3,000 square feet, and for every breakwater, must be signed by a registered professional engineer experienced with floating docks or marinas in conditions at least as demanding as Lake of the Ozarks.
- An annual permit fee of $0.06 per square foot of occupied water space applies to docks and breakwaters over that size. The ordinary $550 new-or-modification fee still applies. The annual fee is additional, billed after the permit is issued.
The $550 does not grow with size for the initial permit. The annual fee is the part that scales. At 3,001 square feet the annual fee is small. At a true multi-slip dock it is not an afterthought. Do the multiplication from Ameren’s final area, not from a sketch that forgot the slips.
Large, but not a marina
Eleven or more slips is Ameren’s “large dock” for a different set of reviews, including agency review as the slip count climbs. That is a separate threshold from the 3,000 square foot fee. A dock can trip one, the other, or both. If you are anywhere near either, say “multi-slip” on the new dock form and expect an engineer in the conversation. This site does not provide the stamp.