Lake Memphremagog is a long (40 km) but narrow (1-3 km) lake, located 130 km to the east of Montreal, Quebec. It is a transboundary lake, receiving 71% of its stream inflow from the Vermont, USA, portion of its catchment, but with 75% of the lake surface area in Quebec, Canada. It is a lake of exceptional, rugged beauty; set in a diverse landscape, hilly and mountainous to the west, but with pastoral, rolling farmland to the east.

The drainage basin of Lake Memphremagog is situated in the physiographic region of the Piedmont. Its early geologic history is tied to the uplift and folding of the Appalachian Mountain chain. The present lake basin was formed about 11,000 B. P. by glacial gouging of a preexisting valley during the final retreat of the Wisconsin glaciation. Following the termination of the Champlain Sea phase, the present lake was formed about 9,500 B. P.

The lake has three distinct basins, a deep Central, and shallower North and South basins. 70% of the lake's watershed is drained by three rivers which enter the lake at the extreme south end and provide the primary input of nutrients into the lake. This has resulted in a distinct nutrient gradient within the lake - the southern end is mesotrophic, while the Central and North basins remain oligotrophic.

The first known settlements were established by the St. Francis Indian community on what they called Lake "Mem-plow-bouque" (large, beautiful expanse of water). The first European settlements were founded in 1793 at Ducansborough (now Newport, Vermont) and in 1794 at Gibraltar Point (now Bolton, Quebec). The Canadian side was largely settled by United Empire Loyalists (settlers who left America after the revolution because they wanted to remain under the British Flag). The lake was popular as a recreation and vacation area in the mid-to-late 1800's, but tourism dropped off sharply after the turn of the century and the area was not subjected to the intensive development pressures and related problems that have affected other river basins in the northeastern United States or southern Quebec. These historical trends are changing as the 1980's brought a new tourism boom and a steady wave of related development to both the American and Canadian portions of the lake basin. The problems associated with increased development have, for the present, been offset by a continuing reduction in crop growing and increased forest regrowth, as well as the installation of tertiary sewage treatment at Newport in 1983 (1, 2, 3).