Champlain Valley southward into the Valley of Vermont. The Vermont Lowlands are primarily underlain by sedimentary rocks, especially limestone and shale, though metamorphic rocks such as marble and slate are also present. Lake Champlain is situated in the Champlain Valley between the Green Mountains of Vermont and the Adirondack Mountains of New York, drained northward by the Richelieu River into the St. Lawrence River at Sorel-Tracy, Quebec (northeast of Montreal). Major tributaries of Lake Champlain include Otter Creek and the Winooski, Missisquoi, and Lamoille rivers in Vermont, and the Ausable, Chazy, Boquet, and Saranac rivers in New York. Lake Champlain also receives
New York State Canal System Cayuga Lake to the Erie Canal; the Oswego Canal connects the Erie Canal to Lake Ontario; and the Champlain Canal connects the Hudson River to Lake Champlain. In 1903 New York State legislature authorized construction of the "New York State Barge Canal" as the "improvement of the Erie, the Oswego, the Champlain and the Cayuga and Seneca Canals". In 1905, construction of the Barge Canal began; it was completed in 1918, at a cost of $96.7 million. It opened to through traffic May 15, 1918. The Barge Canal's new route took advantage of rivers (such as the Mohawk River, Oswego