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
Lake Champlain introduction, spread, and impact of non-native nuisance species to preserve the integrity of the Lake Champlain ecosystem. Senior staff who helped organize the Environmental Protection Agency in 1970 recall that International Paper was one of the first companies to call upon the brand new agency, because it was being pushed by both New York and Vermont with regard to a discharge of pollution into Lake Champlain. Agricultural and urban runoff from the watershed or drainage basin is the primary source of excess phosphorus, which exacerbates algae blooms in Lake Champlain. The most problematic blooms have been cyanobacteria, commonly called blue-green