Washington County, New York is part of the Great Appalachian Valley (also known simply as the 'Great Valley') which is a long narrow valley strip often between tall mountain ranges. The county transitions from the Taconic Mountains to the Adirondack Mountains, and from the Lake Champlain Valley to Hudson River Valley. Much of the county is part of the slate valley of the Upper Taconic Mountains (Taghkanic, meaning 'in the trees'). The eastern boundary of Washington County is the New York–Vermont border, part of which is Lake Champlain. This is also the border with New England proper. The northern end of the county is
Champlain Canal Lake Champlain, between above sea level, at Whitehall. By traveling the length of Lake Champlain, boaters can access the Chambly Canal, which connects Lake Champlain to the Saint Lawrence River. The following list of locks is provided for the current canal, from south to north. There are a total of 11 locks on the Champlain Canal. All locks on the New York State Canal System are single-chamber; the dimensions are 328 feet (100 m) long and 45 feet (13.7 m) wide with a minimum 12-foot (3.7 m) depth of water over the miter sills at the upstream gates upon lift.