Lake of Geneva is shared by Switzerland along the northern shore and France along the southern shore. Geneva, the city of international politics and tourism, is located at the west end of this semilunar lake, while the well- known resort town of Montreux is at the east end. In-between these cities, Lausanne, a cultural centre of western Switzerland, is on the northern shore, and Evian, a town famous for its superior mineral water, is situated in the middle of the southern shore. The climate is gentle with mild winters and comfortable summers, and the surrounding area is particularly known for the well-managed picturesque scenery and resorts set among this natural splendor.

The Rhone River flows southward from the west end of the lake to the Mediterranean Sea. The lake is deep and has a comparatively large water volume for its surface area. The drainage basin is also fairly wide, including about a half of the Walliser Alps and the Berner Alps. Therefore, nutrient loading from natural sources is more or less equivalent in amount to that from industrial and domestic waste water. The dissolved oxygen concentration in the bottom water as well as the transparency has been dropping in recent years. These measurements clearly indicate the progress of eutrophication in the lake. At present, approximately 700,000 people get drinking water from the lake, so that the water quality is under strict legal control by the cantons surrounding the lake.