Agano River

The Agano River (阿賀野川) is a river system in the Hokuriku region of Honshu, Japan. It is also called the Aga River or the Ōkawa River in Fukushima. It is designated as a Class A river.

The source of the river is Mount Arakai on the border of Fukushima and Tochigi prefectures. It flows to the north and meets the Nippashi River from Lake Inawashiro and the Tadami River in the Aizu Basin, and then turns to the west and falls into the Sea of Japan. The Agano River flows for 210 kilometers. It has a watershed area of 7,710 square kilometers. Approximately 560,000 people live in the basin area.

In 1964–1965, a chemical factory at Kanose village in Niigata Prefecture released methylmercury into the river and caused Niigata Minamata disease.

There are several hydroelectric power plants on the Agano River:
 * Inawashiro Power Plant (107.5 MW), constructed in several stages in 1899–1940. It was the site of Japan's first high-voltage, long-range power transmission line.
 * Numazawanuma Power Plant (43.7 MW), constructed in 1952. It was the first pumped-storage power plant in Japan.