Assembling a Steam Gold Dredge, Eastern Oregon - c. 1900

This large steam-powered gold dredge is under construction on an unidentified river somewhere in eastern Oregon, probably near Baker City, where photographer Martin Hazeltine operated his studio. I'd be grateful if you could help me identify the location. Two large boilers, likely coal-fired, provide the power for the dredge. In detail view 1, you can see that the near one is labeled "Left", just to make sure there aren't any mistakes in the assembly process. Detail view 2 shows the rotating drum with gradually increasing sized holes, used to separate out the larger rocks from the more desirable smaller aggregate. -- This photo is restored and printed by Old Oregon.