Hiraoka Dam

Hiraoka Dam
Hiraoka Dam free flow.jpg
LocationTenryū, Nagano, Japan
Construction began1938
Opening date1951
Dam and spillways
Type of damConcrete gravity dam
ImpoundsTenryū River
Height62.5 m
Length258 m
Dam volume252,000 m³
Total capacity42,425,000 m³
Catchment area3,650 km²
Surface area258 ha

Hiraoka Dam (平岡ダム, Hiraoka damu) is a dam in Tenryū, Nagano Prefecture, Japan, completed in 1951.[1] It is located on the Tenryū River upstream from the Sakuma Dam.

During the Second World War prisoners of war held at Tokyo #2D (Mitsushima) Prisoner of War Camp provided labour to build the penstock tunnel to the powerstation, collect aggregate, and mix cement for the construction of the dam between November 1942 and August 1945. Fifty seven prisoners died from diseases relating to poor sanitary, diet, and climate conditions.

See also


  1. ^ "Hiraoka Dam [Nagano Pref.] - Dams in Japan".

Coordinates: 35°16′57″N 137°50′48″E / 35.28250°N 137.84667°E / 35.28250; 137.84667

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