Shimohara Dam (下原ダム, Shimohara damu) is a dam in the city of Gero, Gifu Prefecture, Japan on the middle reaches of the Hida River, which is part of the Kiso River system. The dam is a concrete gravity dam with a height of 23.0 meters. It was completed in 1938 by the Toho Electric Power Company as part of the pre-war Hida River Development Project and was taken over by the Chubu Electric Power Company from 1951. The dam was constructed exclusively for hydroelectric power generation and generates a maximum of 22,000 kilowatts at the Shimohara Power Station downstream of the dam. The dam is located with the borders of the Hida-Kisogawa Quasi-National Park.

Shimohara Dam
Official name下原ダム
LocationGero, Gufu, Japan.
Coordinates35°42′25″N 137°10′57″E / 35.70694°N 137.18250°E / 35.70694; 137.18250
Construction began1933
Opening date1938
Dam and spillways
ImpoundsHida River
Height23 meters
Length102.5 meters
Reservoir
Total capacity2,936,000 m3
Catchment area1,147.0 km2
Surface area35 hectares
Power Station
Installed capacity22.0 MW