Map of the project
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.
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 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.
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.
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.
