Ontario Hydro examined the possibilities of hydro-electric power generation on the Mississagi river in 1919, surveying the shoreline between Slate Falls and Grand Falls. Several decades later, in 1950, the waters of the Mississagi River were harnessed for hydro-electric power production at Wharncliffe. The Rayner generating station was the first station to be built on the river, introducing electricity to the Mississagi River Valley.

A total of four generating stations (dams) have been constructed by Ontario Hydro on the Mississagi River: Rayner G.S., Wells G.S., Red Rock Falls G.S., and Aubrey Falls G.S.

Before Ontario Hydro arrived, Wharncliffe was a small pioneer community with a one lane dirt and mud road, a store, a school, a church, and no electricity. With Hydro in town the population increased with all of the worker's families, and with a larger population the store made enough of a profit that the owners decreased the prices of all merchandise. The community was built up with all of the jobs available through the constuction of the dam. The roads were greatly improved, and Wharncliffe finally got power.