The Bonanza River flows northwest from Mount Ashwood to Bonanza Lake and then north to Ida Lake and the Kokish River.

The area is underlain by basalts and lavas of the Upper Triassic Karmutsen Formation (Vancouver Group). The volcanics are intruded by Late Jurassic granodiorite of the Nimpkish Batholith, which is part of the Jurassic Island Plutonic Suite.

It appears that most of the gold is derived from bars or in crevices in the bedrock of the river bed, or from benches along the side of the creek.

In 1980, the Bonanza River and its tributaries were declared a designated placer area. Several placer claims were staked near the mouth of the Bonanza River on Bonanza Lake but no production from these claims has been recorded.

In 1988, panning of river concentrate from a canyon along the river yielded fine colours and a few flakes of gold (Assessment Report 17512).