The Wanapum dam was originally licensed in 1955 for a period of 50 years. Construction was initiated in 1959 with initial beneficial operation in 1963. The initial license expired in 2005, after which the Grant County PUD operated the dam on yearly license extensions while negotiations for license extension proceeded. The Federal Energy Regulatory Commission approved a license extension of 44 years for both the Wanapum dam and the downstream Priest Rapids dam on April 17, 2008. The license extension was conditioned upon programs to:
modernize the power generation capability of the dam,
monitor water quality,
improve wildlife habitat,
protect nearly 700 Wanapum Tribe archaeological sites in the vicinity, and
enhance recreation with new campsites, picnic areas and trails.