Wisconsin has Great Lakes water on two sides and Western Rivers water on the third. Door County, Sturgeon Bay, Milwaukee and Sheboygan are Lake Michigan; the far north is Lake Superior; both are inland water by definition under 33 CFR 83.03(q), with no Part 80 line and with the 83.23(e) all-round white light option available. The Mississippi along the western border is Western Rivers under 83.03(n), a different set of provisions. Lake Winnebago is an ordinary inland lake. The credential point for the Door County charter fleet is 46 CFR 11.467(b): a plain inland OUPV endorsement covers all inland waters EXCEPT the Great Lakes, so the endorsement that matches the work is Great Lakes and inland, and REC Toledo is where that is settled.
33 CFR Part 80 draws no demarcation line in Wisconsin. Its 106 sections cover the Atlantic, Gulf and Pacific coasts, Puerto Rico and the Virgin Islands, the Pacific islands and Alaska; a state with no coast has no section, which is itself the answer.
Great Lakes water (Lakes Michigan and Superior) needs no Part 80 line: 33 CFR 83.03(q) defines inland waters to include the waters of the Great Lakes on the United States side of the International Boundary. Under 46 CFR 11.467(b) a plain inland OUPV endorsement covers all inland waters except the Great Lakes.
Western Rivers (the upper Mississippi River) are defined at 33 CFR 83.03(n) and carry Inland Rules provisions the rest of inland water does not: 83.09(a)(ii), 83.14(d), 83.15(b) and the towing-light exception at 83.24(j).
This decides which rulebook you steer by, not where your credential may operate: the route limit is the 46 CFR Part 7 Boundary Line, and the two lines are not drawn in the same place. How the two lines differ · International Rules · Inland Rules
33 CFR Part 80 and the Part 83 definitions above read from eCFR on 12 Aug 2026. Any specific water is a determination for the cognizant Coast Guard Officer in Charge, Marine Inspection.