Originating in a series of lakes near the crest of the Cascade Mountains, the Clackamas flows 80 miles northwest and empties into the Willamette River at Oregon City. Its drainage covers more than 900 square miles.
Starting in the early 1900s, and over a span of seven decades, PGE constructed four hydroelectric plants on the river that still provide emissions-free, renewable power today: Faraday, River Mill, Oak Grove and North Fork.
Counting fish runs
Clackamas River fish runs are one of the most closely monitored in the state. We count adults migrating upstream and juveniles migrating downstream.
Fish passage on the Clackamas
River Mill Dam is the first structure encountered by fish migrating upstream. Its original 1912 fish ladder was replaced in 2006 by a new ladder that provides more resting pools and a more gradual ascent over the dam.
Faraday Diversion Dam is the next upstream and is designed with a 1.9-mile-long fish ladder that provides passage over this and the next, North Fork Dam.
At Faraday, adult salmon are counted and hatchery salmon are removed. Wild salmon move up the ladder and exit into North Fork Reservoir, where they continue up the Clackamas River.
The hatchery fish are moved downstream by truck where they are released for fishing or taken to the ODFW hatchery, where they are used for the production of additional hatchery salmon.
Juvenile fish migrating downstream from the upper reaches of the Clackamas are collected just above North Fork Dam. The fish are then released into a 20-inch diameter pipe that carries them about five miles downstream, returning them to the main river below River Mill. Before they are released into the Clackamas River, PGE counts and evaluates the condition of the juvenile migrants.
Protecting fish and habitat
We are partners in the management of the fisheries resources in the Clackamas basin, along with the Oregon Department of Fish and Wildlife, the National Marine Fisheries Service, the U.S. Fish & Wildlife Service, and the U.S. Forest Service.
As part of our license to operate hydropower projects on the Clackamas River, we fund habitat restoration projects that protect and restore wetlands, improve riparian areas (including planting shade trees and controlling runoff into the river), and restore instream habitat in areas where native fish migrate, spawn and rear.
Faraday Powerhouse and Diversion Dam
Originally named Cazadero, our first dam on the Clackamas, Faraday began operation in 1907 at a site just east of Estacada, and was rebuilt after damage from a 1964 flood. This dam does not produce power, but diverts water to Faraday Lake, where water flows through the Faraday powerhouse and into Estacada Lake, the two-mile stretch of water behind River Mill Dam.
Six turbines at the Faraday powerhouse annually generate enough electricity to power more than 17,000 homes.
North Fork Dam
The North Fork facility, which generates enough electricity to power nearly 20,000 homes, went into operation in 1958. The project created a 331-acre lake with which PGE controls river flows at North Fork, Faraday and River Mill.
Oak Grove Powerhouse
Located 23 miles east of Estacada, our Oak Grove plant began operations in 1924. As the powerhouse was being built, a diversion dam was constructed on the Oak Grove Fork of the Clackamas River. The storage reservoir behind this dam is known as Lake Harriet, and is located above waterfalls that prevent salmon passage.
Water is diverted through a four-mile-long pipeline to Frog Lake, where it again travels two miles through a pipeline down to the Oak Grove powerhouse, which produces enough electricity to power more than 24,000 homes. Because of the high velocities created by the sharp drop in elevation, this is PGE’s most efficient hydro facility.
In 1956, Timothy Lake was created to provide additional storage. In the summer months, the lake is maintained full to provide recreation opportunities. During the rest of the year, the lake is managed to capture rain and snow melt for peak operation of the Oak Grove plant.
Timothy Lake has kokanee, eastern brook, rainbow and cutthroat trout. The Oregon Department of Fish and Wildlife stocks the lake with rainbows throughout the summer. There is no fish passage out of the lake, which is host to a number of PGE-owned, public parks and campgrounds.
Designed by engineer Nils F. Ambursen, this system of construction (also called a slab and buttress dam) requires far less concrete than a solid core dam, are less expensive, and could be built fast to meet the growing demand for electricity. Today, River Mill is one of the few original operating Ambursen-designed dams in the country.