- December 1957 The Ibi River was selected for study by the Electric Power Development Company at the 23rd Electric Power Development Coordinating Meeting
- May 1976 The Ministry of Construction releases the bulletin "Policy on Tokuyama Dam Construction Project"
- December 1982 Project incorporated into Electric Power Development Basic Plan at the 90th Electric Power Development Coordinating Meeting 400 MW pumped storage plan
- May 2000 Construction on main part started
- May 2004 Plan for electrical output changed from 400 MW of pumped-storage hydropower to start in 2008, to 153 MW of conventional hydropower to start in 2014
- September 2006 Experimental filling of the reservoir behind the Tokuyama Dam began