Wanapum Dam is a hydroelectric project located on the Columbia River downstream (south) from Vantage, Washington where Interstate 90 crosses the Columbia from Grant County into Kittitas County. It is owned by the Grant County Public Utility District. Its reservoir is named Lake Wanapum. The dam, and its lake, are named after the Wanapum Indians. At height of 185 feet and a length of 8,320 feet the dam has a rated capacity of 1,040 megawatts and annually generates over 4 million megawatt-hours.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 Company employed 55% Indian Band members for building of the dam and at the time it was the largest construction project in the country.