Agano River

Agano River
Agano River, 5/5/2007
Native name	阿賀野川
Basin
Main source	Mount Arakai, border of Fukushima Prefecture and Tochigi Prefecture 1,581 m (5,187 ft)
River mouth	Sea of Japan, Niigata Prefecture 0 m (0 ft) 37°57′48″N 139°07′46″E / 37.963224°N 139.129556°ECoordinates: 37°57′48″N 139°07′46″E / 37.963224°N 139.129556°E
Size	7,710 km^2 (2,980 sq mi)
Countries	Japan
Physiognomy
Length	210 km (130 mi)
Discharge	Average rate: 451 m^3/s (15,900 cu ft/s)

It is called the Aga River or the Ōkawa River in Fukushima.

The source of the river is Mount Arakai on the border of Fukushima and Tochigi. 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. Its river mouth flow (451 m³/s, averaged from 1951 to 2002), is the largest of any river in Japan. The Agano River flows for 210 kilometers. It has a watershed area of 7,710 square kilometers.^[1] Niigata plain is formed mostly by Agano river sediments.

Large tributaries of Agano River are Araki river, Aga River, Koagano River, Tadami River, Nippashi River (draining Lake Inawashiro).

In 1964-1965, a chemical factory at Kanose village in Niigata Prefecture released methylmercury into the river and caused Niigata Minamata disease. According to report of Japanese Ministry of the Environment in 2012, the mercury concentration in water is below 0.0005 mg/L, therefore river is considered safe.

The Agano River is feeding several notable hydroelectric power plants:

• Inawashiro Power Plant (107.5 MW), constructed several steps in 1899-1940. It was the site of the Japan 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.
• 10 hydroelectric plants totaling 1.65 GW capacity are located on Tadami River

Agano River near Kitakata

Agano River in Aga town

References

1. "Agano River". Tourist Link. Retrieved 4 March 2013.