Cougar Reservoir is formed by a dam on the south fork of the McKenzie River. It's late in the summer, so water levels are low. Still jaw-dropping beautiful, though. My brother, whose work partially involves Oregon's waterways and dams, stopped here to take photos thinking he could maybe write off the cost of Cycle Oregon as a business expense. Can't!! I was more excited about the downhill I knew would come after passing the 700 ft high dam. And I wasn't disappointed.