Tennessee is Western Rivers country from end to end: the Mississippi at Memphis, and the Tennessee and Cumberland across the state, are all inside the 33 CFR 83.03(n) definition, and no Part 80 line is drawn anywhere in the state. That makes the river provisions the working rulebook rather than an exception — 83.09(a)(ii) and 83.14(d) give the downbound vessel with a following current the right of way and the duty to propose the manner of passage, 83.15(b) reverses the crossing rule for a vessel crossing the river, and 83.24(j) changes the towing lights. Watts Bar, Norris and Pickwick are impoundments on the same system and their exact status is an OCMI question. REC Memphis sits on the Mississippi itself, which is convenient for asking it.
33 CFR Part 80 draws no demarcation line in Tennessee. 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 Mississippi, Tennessee and Cumberland Rivers) 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.