Code of Federal Regulations Title 33. Navigation and Navigable Waters § 33.175.105 Definitions

(1) The U.S. waters of the Great Lakes (Lake Erie, Huron, Michigan, Ontario, and Superior);

(2) The territorial seas of the United States;  and

(3) Those waters directly connected to the Great Lakes and territorial seas (i.e., bays, sounds, harbors, rivers, inlets, etc.) where any entrance exceeds 2 nautical miles between opposite shorelines to the first point where the largest distance between shorelines narrows to 2 miles, as shown on the current edition of the appropriate National Ocean Service chart used for navigation. Shorelines of islands or points of land present within a waterway are considered when determining the distance between opposite shorelines.