Lake Memphremagog is a fresh water glacial lake located between Newport, Vermont, United States and Magog, Quebec, Canada. The lake spans both Quebec and Vermont, but is mostly in Quebec. Most of the watershed that feeds the lake is located in Vermont, and is a source for accumulated phosphorus, sediments and other pollutants. Recent cleanup efforts have started to improve the water quality. The lake furnishes potable water for 200,000 people.Physical characteristicsThe lake is 31mi long with 73 percent of the lake's surface area in Quebec, where it drains into the Magog River. However, three-quarters of its watershed, 489sqmi, is in Vermont. The total is 687sqmi, with 198sqmi located in Quebec. In Vermont, the lake lies in parts of the towns of Derby and Newport, in addition to the City of Newport, all in Orleans County. In Quebec, the lake lies in parts of Austin, Magog, Ogden, Potton, Saint-Benoît-du-Lac, and Stanstead Township, all in Memphrémagog Regional County Municipality. The lake occupies most of what the Vermont Agency of Natural Resources calls "Basin 17." At the very south end of the lake, there is the South Bay, connected by the narrowest part of the lake.