It is currently owned by FirstLight Power Resources[1] (formerly NE Energy), which purchased the facility from Northeast Utilities in 2006.
[2] Engineering studies for the plant began in October 1964, with early site preparation starting three years later.
[citation needed] The facility was built to balance the supply from the nearby Vermont Yankee Nuclear Power Plant.
[3] The plant was built entirely underground, and located about 5.5 miles (8.9 km) up the Connecticut River from Turners Falls Dam.
Northfield Mountain's upper reservoir covers 300 acres (120 ha) at 800 feet (240 m) above the river, with total storage of 17,186 acre-feet (21.199 GL) of water.