The Lewis River Hydroelectric Projects - PacifiCorp

Lewis River Interpretive & Education Plan
The Forest Service used the Lewis River Trail as access to remote operations in
the upper Lewis River and beyond. These operations included fire prevention,
fire detection (the trail was a critical access line for regional fire lookouts), and
recreation development.
Today, the Forest Service continues to be a player in the story of the Lewis River.
Much of the river’s upper watershed lies on National Forest lands, and many
recreationists are drawn to the region by the nearby Mt. St. Helens National
Volcanic Monument, administered by the Forest Service.
Dams and Change
Plans for creation of hydroelectric plants on the Lewis River began at the turn
of the 20th century. In the 1920s, surveyors from Inland Light and Power (a
predecessor of Pacific Power/PacifiCorp) began photographing the lands that
would eventually be flooded by the Ariel Dam. Land agents worked to buy up
the properties and homesteaders gradually moved out—some took up work on
dam construction or supporting the new “town” that sprang up at Ariel, others
to establish new farms or enterprises elsewhere.
The Hydroelectric Story
The building of Ariel Dam (now Merwin Dam) was just the beginning of the
“electrification” of the Lewis River. Construction of the Merwin Dam began in
1929 and was completed in 1931. Yale Dam was completed in 1953, and Swift
Dam was completed in 1958. Plans for two other projects further upstream were
never carried out.
Hydro Projects of the
Lewis River
The three lakes of the Lewis River: Merwin, Yale, and Swift (and their associated
reservoirs) are focal points of the valley. To many people, the lakes may seem
like natural landscape elements; there are few places on the main roads from
which the dams can be seen. For many, the lakes are seen primarily as recreation
sites: great places to go waterskiing, fishing, swimming, camping, But these
lakes are actually working reservoirs. All three were constructed for the primary
purpose of supplying electricity. They are all owned and operated (under a
Federal Energy Regulatory Commission license) by PacifiCorp Energy, a power
utility company. An additional hydroelectric facility, the Swift No. 2 Project
canal between Swift Dam and Yale Lake, is owned by Cowlitz County PUD and
operated by PacifiCorp.
Merwin (Ariel) Project
In the 1920s, Inland Light and Power (later to become Pacific Power and Light,
and eventually PacifiCorp) began buying lands in the area above Shirt-tail
Canyon, in the region that would eventually be flooded by Lake Merwin. This
area had been settled at a medium density by homesteaders in the late 1800s;
Sea Reach Ltd • 146 NE yamhill Street • Sheridan, OR draft 3 • November 2008 • page 67