Sevan (syĭvänˈ) [key], lake, c.540 sq mi (1,400 sq km), NE Armenia, at an altitude of 6,280 ft (1,914 m); it is 324 ft (99 m) deep. The largest lake of the Caucasus, it is fed by some 30 streams, but the Razdan River is its only outlet. Lake Sevan is free of ice in winter. From 1940 to 2002, the Sevan-Razdan hydroelectric project drained much water from the lake. A tunnel built in the 1970s to bring additional water into the lake failed to refill the lake until the power plant was closed. A second water tunnel to the lake was finished in 2003, and water levels are now rising. The lake's commercial fisheries have become overfished since the 1990s. On a peninsula (formerly an island) on the northwest shore stand two churches and other remains from a 9th-century Armenian monastery.