Map of the project

Carmen Diversion Dam and Reservoir

The Carmen-Smith project begins just a quarter-mile below Koosah Falls, where water flows into the 30-acre Carmen Diversion Reservoir. There, the water is transported through an 11,381-foot tunnel into Smith Reservoir, a 170-acre impoundment on the other side of a mountain ridge. 

Smith River Dam and Reservoir

At the face of Smith Dam, a second tunnel transports water another 7,325 feet to a penstock, a 1,160-foot-long, 12-foot-diameter underground vertical pipe that is embedded in concrete. As water enters the penstock, gravity accelerates the velocity of the water as it rushes downward toward the Carmen Power Plant at the upper end of Trail Bridge Reservoir. The water enters the power plant and turns large turbines, generating up to 104,500 kilowatts of electricity. The water is discharged into Trail Bridge Reservoir.

Trail Bridge Reservoir

Trail Bridge Reservoir is about 74 acres in size and is a “re-regulating” reservoir, meaning it is used to maintain a near-natural level of water in the river below the project. A second powerhouse is located at the face of Trail Bridge Dam and generates about 10,000 kilowatts.

Below Trail Bridge Dam, water is returned back to the river.

Transmission line

Power is transmitted over a 115,000 volt, 19-mile line from Carmen Substation to Cougar Dam area, where it is then transmitted on a BPA-operated power line another 42 miles to EWEB’s power distribution system.

Salmon spawning channel

An artificial spawning channel was built alongside the main McKenzie River bed just below Trail Bridge Dam to assist Spring Chinook salmon in their journey back to the upper McKenzie in mid-to-late summer, with spawning occurring in September and October. Public access to the channel is controlled to avoid undue disturbance to the naturally spawning fish.