Mountain Island Lake was created in 1924 to coincide with the building of Mountain Island Hydroelectric Station. It is named after the mountain which appears as an island in the lake. Mountain Island Lake is fed by the Catawba River, and is the smallest of the three man-made lakes that border Mecklenburg County, North Carolina (Lake Norman, and Lake Wylie). Mountain Island Lake is managed by Charlotte-based company Duke Energy. The primary function of Mountain Island Lake is to provide drinking water for residents of Charlotte, Mecklenburg County, as well as Mount Holly and Gastonia,Gaston County. The lake is also accessible to the public for boating and fishing use.
The lake generates hydro-electric power and supports Riverbend Steam Station by cooling the steam that drives the turbines.