Yamba Dam

Yamba Dam (八ッ場ダム, Yamba damu) is a dam in Naganohara, Agatsuma District, Gunma Prefecture, Japan. Construction began in 1967, with effective completion in October 2019^[1] and the official opening on 1 April 2020.

八ッ場ダム Yamba Dam
Location	Gunma Prefecture, Japan
Coordinates	36°33′25″N 138°42′51″E
Construction began	1967
Opening date	2019
Construction cost	532 Billion Yen
Dam and spillways
Type of dam	Gravity
Impounds	Agatsuma River
Height	131 m (430 ft)
Length	336 m (1,102 ft)
Reservoir
Creates	Lake Yamba-Agatsuma
Total capacity	107,500,000 m3 (3.80×109 cu ft)
Catchment area	707.9 km2 (273.3 sq mi)
Surface area	304 hectares

History

Planning for the dam began in 1952, and it was planned to be completed by 2015. The dam's construction had seen sustained local opposition and a ballooning budget, and a change of National government in 2009 resulted in the project being halted, being about 70% completed at the time. Another change of government in 2012 resulted in the project being revived and subsequently completed.

Construction required the relocation of part of the Agatsuma Line, several roads and affected residents.

Test flooding of the reservoir began on 1 October 2019.^[1]

Yamba Power Plant, an 11,700 kW hydroelectric station attached to the dam, began operation on 1 April 2021.^[2][3]