|Location||Tenryū, Nagano, Japan|
|Dam and spillways|
|Type of dam||Concrete gravity dam|
|Dam volume||252,000 m³|
|Total capacity||42,425,000 m³|
|Catchment area||3,650 km²|
|Surface area||258 ha|
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.
- "Hiraoka Dam ［Nagano Pref.］ - Dams in Japan".