This article needs additional citations for verification. (December 2009)
|Primary inflows||Tama River, Kosuge River|
|Primary outflows||Tama River|
|Surface area||4.25 km2 (1.64 sq mi)|
|Max. depth||142 m (466 ft)|
|Surface elevation||526.5 m (1,727 ft)|
Lake Okutama (奥多摩湖, Okutama-ko) is in Tokyo and Yamanashi Prefectures in Japan. Lying above the Ogōchi Dam, it is also known as the Ogōchi Reservoir. Lake Okutama is an important source of drinking water for Tokyo.
The Taba ( Tama) River feeds Lake Okutama at its western end. From the southwest, the Kosuge River also flows into the lake. The Tama River drains the lake at the eastern end. The surroundings are famous for cherry blossoms in the spring.