Sevan, Lake

Sevan, Lake, large alpine lake on the Armenian Highland, the largest lake in Armenia. Lake Sevan lies in a basin enclosed by the Caucasus Mountains, at an elevation of about 1,900 m (6,234 ft). It has an area of about 1,400 sq km (540 sq mi). The lake's greatest depth, located in its north-east section, is about 83 m (272 ft). Numerous tributaries flow into the lake, principally from the south and south-east, but its only outlet is the River Hrazdan. The beauty of Lake Sevan and the surrounding mountains make the area a popular centre for recreation. Several ancient Armenian churches lie along its shores.

A project was started in the 1930s to divert almost all of Lake Sevan's waters to the Hrazdan for irrigation and to generate hydroelectric power. By the end of the 1950s a series of power stations had been built on the river, and nearly a third of the lake's water had been drained. The project was abandoned, however, due to unanticipated environmental problems and the availability of new sources of energy from neighbouring republics.

A new water management project, developed in 1960, envisioned the stabilization of Lake Sevan's water levels by restricting water use to extreme cases and by constructing a tunnel to divert part of the Arpa River to the lake. After 18 years of construction (1963-1980) the tunnel, measuring 48 km (30 mi), was completed, and the lake's level began to stabilize. From 1981, when the tunnel started operation, to 1986, the lake's level increased slightly. The tunnel was closed for repairs in 1986.