General Information River : The Maze,one of tributaries of the Kiso. Location : Kanayama-cho,Gero-city,Gifu Pref.,50km northeast of Gifu City. Purpose Flood control Reducing estimated flood discharge from 2,400 to 300m3/sec. Irindustal water supply 　 Max.discharge 17.63m3/sec. Municipal water supply 　 Max discharge 21.93m3/sec. Irrigation 　 Max discharge 6.13m3/sec. Power generation 　 Owner,Chubu Electric Power Co.,Inc;Installed capacity,288,000kw (Turbine discharge 335m3/sec) Typical cross section 　 Height 127.5m Lengh 336m Volume of dam 5,780,000m3 Catchment area (direct) 265km2 Catchment area (indirect) 770km2 Reservoir area 4.26km2 Gross storage capacity 173,500,000m3 Effective storage capacity 150,000,000m3 Capacity allocation chart,of the reservoir Iwaya Dam Site −　Surcharge water level EL.424.0m. Flood control capacity 50,000,000ｍ3 −　Normal water level EL.411.0m. − Low water level EL.366.0m. − Foundation rock EL.300.0m. ↑　Water utilization capacity 100,000,000ｍ3. ↑　Sediment capacity 23,500,000ｍ3. ↑　Effective storage capacity 150,000,000ｍ3. ↑　Gross storage capacity 173,500,000ｍ3. Incorporated Administrative agency/Japan Water Agency Iwaya Dam Operation & Maintenance Office 6-27 Unohara Kanayama-Town  Gero-City  Gifu Pref 509-1602 Japan