42°36′39″N 72°28′17″W / 42.61083°N 72.47139°W Northfield Mountain is a pumped-storage hydroelectric plant and reservoir located on and under the similarly named Northfield Mountain in Erving and Northfield, Massachusetts. It is currently owned by FirstLight Power Resources[1] (formerly NE Energy), which purchased the facility from Northeast Utilities in 2006.[2]