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
Lake Champlain restoration plan for Lake Champlain was first endorsed in October 1996 by the governors of New York and Vermont, and the regional administrators of the United States Environmental Protection Agency (EPA). In April 2003, the plan was updated, and Quebec signed onto it. The plan is being implemented by the Lake Champlain Basin Program and its partners at the state, provincial, federal, and local levels. Renowned as a model for interstate and international cooperation, its primary goals are to reduce phosphorus inputs to Lake Champlain, reduce toxic contamination, minimize the risks to humans from water-related health hazards, and control the