The Lewis River Hydroelectric Projects - PacifiCorp

Lewis River Interpretive & Education Plan
Other Wildlife
Conservation
The face of Yale Dam has developed into a particularly interesting habitat.
The moist, mossy boulders shelter several different species of reptiles and
amphibians, including rubber boas, alligator lizards, western red-backed
salamanders, and Larch Mountain Salamanders, a species of concern for
conservation.
On one of PacifiCorp’s power line right-of-ways above Swift Reservoir, there are
some lava tubes that contain both a hibernaculum (a hibernation chamber) and
a nursery cave for Townsend’s big-eared bats—a sensitive species. The power
line clearing appears to be helping the bats by keeping their nursery cave warm.
PacifiCorp is cooperating with the Nature Conservancy to conserve this area; in
the vicinity of the caves, ROW clearing is done after the young bats have finished
rearing, and is done with only hand tools, to minimize disturbance.
Fish Enhancement
The Lewis River has always been a significant river for anadromous fish.
Chinook, coho, pink and chum salmon are all known to have been historically
present in this system. Prior to Euroamerican settlement and commercial fish
harvest, the largest fish runs in the Lewis River were chum salmon sometimes
exceeding 300,000 spawners. The construction of the Merwin Dam (and later
the Yale and Swift dams) presented several challenges to these fish species.
All dams impede the passage of migratory fish (in the case of Merwin, the dam
completely prevents salmon from migrating upstream—it is too tall for a fish
ladder). Dam turbines cause mortality in outmigrating smolts. Dams slow the
flow of water in the river, which can change the temperature and chemistry of
the water, affecting fish. Dams also inundate former fish habitat.
Since the Lewis River dams were first built, the power company that has
operated them (first Inland Power and Light, then Pacific Power and Light, now
PacifiCorp) has held the responsibility of mitigating those effects by supporting
the supplementation of wild runs and the easing of the passage of fish to their
natural spawning grounds. The company does this by funding hatchery and
stocking operations, and through habitat protection and enhancement.
Hatchery Operations
Early efforts to supplement wild runs consisted of hatcheries combined with
fish-hauling operations to physically transport migrating fish over Merwin
Dam and release them into the lake above. These efforts were not successful
(escapement through dam turbines was very poor) and they were abandoned
after a few years when the fish runs significantly diminished.
Sea Reach Ltd • 146 NE yamhill Street • Sheridan, OR draft 3 • November 2008 • page 81