The Pyotan Waterfall is a unique waterfall on the Nakasatsunai River in Nakasatsunai Village, Kasai-gun, Tokachi, Hokkaido. In 1954, a dam was constructed for a small hydroelectric power station to supply electricity to nearby villages. It was a gravity type power station, which used the water flowing down from the dam. The production of electricity was about 120 kw, which was enough for the whole village area. The local people thanked the dam and called it “Nokyo Dam (the dam of the local agricultural cooperative).” However in the next year an unprecedented flood attacked the area and the dam was submerged by the upstream earth and sand, which formed the Pyotan Waterfall. “Pyotan” means “a place with a lot of pebbles” in Ainu. Natural power may have brought too many pebbles to the village, but at the same time it also brought what man cannot produce.