[3] Construction on the dam began and its original 390 MW power station was commissioned 2 December 1960.

In addition, a 2.7 MW generator was added to ensure a flow of 2.5 m3/s (88 cu ft/s) downstream for environmental purposes.

Sitting at the head of a 595 km2 (230 sq mi) catchment area, the dam creates a reservoir with a 601,000,000 m3 (487,239 acre⋅ft) capacity of which 458,000,000 m3 (371,307 acre⋅ft) is active (or "useful") storage.

After being received by the dam's intake, water supplied to the original power plant travels down three penstocks 185–189 m (607–620 ft) in length before reaching an individual 120 MW Francis turbine-generator.

After water is processed through the generators, it travels down two tailrace tunnels before being discharged over 3 km (2 mi) downstream at the upstream edge of the Otori Reservoir.