The Tama River is a major river in Yamanashi, Kanagawa and Tokyo Prefectures on Honsh?, Japan. It is officially classified as a Class 1 river by the Japanese government.
Its total length is 138 km, about 85.75 miles, and the total of the river's basin area spans 1.240 km2, more than 770 square miles.
The river flows through Tokyo, on the dividing line between Tokyo and Kanagawa. In the city, its banks are lined with parks and sports fields, making the river a popular picnic spot.
Its source is located in Mt. Kasadori in Koshu in Yamanashi Prefecture. From there, it flows eastward into mountainous western Tokyo, where the Og?chi Dam forms Lake Okutama. From there, it takes the name Tama, and flows eastwards through Chichibu Tamakai National Park towards ?me, Tokyo.
>From there flows southeast between Tama Hills and Musashino Terrace. At Hamura is the source of the historic Tamagawa Waterway built by the Tamagawa brothers in 1653 to supply water to Edo (present day Tokyo). Further downstream, the river forms the boundary between Tokyo and the city of Kawasaki in Kanagawa Prefecture. Its mouth on the heavily industrialised Tokyo Bay is next to Haneda Airport.
(Reference: wikipedia, wikitravel)