The Kyushu Electric Power Company, or Kyuden (九電), runs a hydroelectric power plant in Minami Aso (a map is at the link) shaped like a Y, with the upper two branches being concrete-lined feeder streams to a holding pond at the junction which feeds into a pipe running down the mountain face to the generation unit.
According to the Kumanichi, the right branch of the feeder streams ruptured following the April 16th quake, releasing about 10 million cubic liters of water (the article notes this is equivalent to 400 25-meter swimming pools) to the top of the hill which subsequently collapsed in the landslide that severed the train line and Route 57 and also destroyed the Aso Ohhashi bridge.
Flow to the right branch of the feeder streams has been halted, though the power plant is able to continue functioning solely with flow from the undamaged left branch. Authorities have not yet been able to establish a relationship between this leak and the landslide, but investigations continue. - William
