Oklahoma has no 33 CFR Part 80 line, so every navigable water in the state is inland water under 33 CFR 83.03(q). The McClellan–Kerr Arkansas River Navigation System is the state's genuine commercial waterway and the Arkansas is a Mississippi tributary within 83.03(n), so Western Rivers provisions can be in force there. Lake Texoma is an impoundment on the Red River, and the Red River IS named in 83.03(n) — but that clause names it in the context of the Atchafalaya above the Port Allen–Morgan City Alternate Route, so whether a Red River impoundment 600 miles upstream falls inside the definition is an OCMI determination and this page does not guess it. Grand Lake and Lake Eufaula are impoundments on the Neosho and Canadian. Log each water by name.
33 CFR Part 80 draws no demarcation line in Oklahoma. 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.
Western Rivers (the Arkansas River navigation system) 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.