Deria-Shirin (the Sweet Lake) by Persians and Kiagar-couni-sou by Armenians. The Turkic name Gokcha or Gökche, which means "blue lake' appeared in Russian and British sources from the 19th century on. Significance Cultural Along with Lake Van and Lake Urmia, Sevan is considered one of the three great "seas" of historic Armenia. It is the only one within the boundaries of present-day Republic of Armenia, while the other two are located in Turkey and Iran, respectively. Lake Sevan is considered the "jewel" of Armenia and is "recognized as a national treasure" in the country. The 2001 Law on Lake Sevan defines the lake as "a strategic ecosystem valuable for its environmental, economical, social, scientific, cultural, aesthetic, medical, climatic, recreational, and spiritual value." Chardin in 1673 noted the "extraordinary sweetness of the Water", the "small Island in the middle of it; where stands a Monastery built about 600 years ago, of which the Prior is an Archbishop", and "nine sorts of fish which are there taken; the fairest trouts and carps which are eaten at Erivan being caught in this Lake". Naturalist and traveler Friedrich Parrot, best known for ascending Mount Ararat in 1829 for the first time in history, wrote that, Economic It is important for the Armenian economy: being the main source of irrigation water, Sevan provides low-cost electricity, fish, recreation, and tourism. Origin Sevan originated during the early Quaternary when a Palaeo-Sevan, ten times larger than the present lake, came into existence by tectonic formation. The current lake was formed some 25 to 30 thousand years ago. Human intervention Exploitation and reduction Background Sevan was recognized as being a major potential water resource in the 19th century. Its high altitude location relative to the fertile Ararat plain and limited energy resources attracted engineers to explore ways of usage of the lake's water. In his 1910 book, Armenian engineer Sukias Manasserian proposed using Sevan's water for irrigation and hydroelectric power generation. He proposed draining the lake by . Major Sevan would completely dry out, while Minor Sevan would have a surface area of . Implementation Manasserian's proposal was adopted by the Soviet authorities in the 1930s when, under Joseph Stalin, the country was undergoing rapid industrialization. Works on the project started in 1933. The riverbed of Hrazdan was deepened through excavation. A tunnel was bored around under the lake's surface. The tunnel was completed in 1949 and thereafter the