The river follows fractures in the 2.6 billion-year-old bedrock, and the exposed rock is granodiorite.

[3] It generates power to support a Kimberly-Clark pulp and paper plant at Terrace Bay.

In 1945, the Hydro-Electric Power Commission of Ontario began preliminary survey work for a planned hydroelectric facility in the Terrace Bay area.

The development required five million hours of labour, a network of access roads, and the erection of 25 buildings including staff housing, a hospital, administration office, pump house, machine shops and laundry.

The dam enlarged Hays Lake to five hundred times its original size, and forced the relocation of Ontario Highway 17, requiring a new bridge be constructed.