The Lewis River Hydroelectric Projects - PacifiCorp

Speelyai Park—Interpretive sign #1 (Hydroelectric/Natural
History)
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Speelyai Park
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Fish and Dams
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 provide challenges to migratory fish. Many dams are too tall for
fish ladders. Spinning turbines can kill young fish (smolts) as they
migrate downriver. 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.
But with careful planning and effort, fish populations can be sustained on
dammed rivers. Since the Lewis River dams were first built, PacifiCorp
has worked to provide ways in which fish and dams can coexist.
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Photo of stocking operation
Each year, PacifiCorp-funded hatcheries stock Merwin and Swift
reservoirs with thousands of rainbow trout and kokanee.
One important way in which PacifiCorp supports fish runs on the Lewis
is through funding hatchery programs at Merwin Dam and here at
Speelyai Bay. Each year, spring Chinook, steelhead and coho salmon are
trapped as adults as they arrive at Merwin dam and trucked to holding
ponds at Speelyai or Merwin Hatchery. Here at Speelyai, Chinook and
coho are spawned in the fall; the eggs are incubated in Speelyai Creek
water and the young fish are reared first in raceways and then in net pens
(watch for them in Speelyai Bay). When they reach smolt stage, the young
salmon are trucked below the dam and released into the Lewis River.
The Merwin fish trap is located at the base of the dam. Imprinted on the
scent of Speelyai Creek and Lewis River water flowing out from the dam,
the fish cluster in a large well. From there, they are transferred by hand to
a large tank and immediately put in special fish-transport trucks for their
trip to the hatchery.
Because hatcheries are no substitute for self-sustaining runs of fish,
PacifiCorp funds programs aimed at restoring natural populations of
Appendix 1: panel profiles Lewis River Draft I&E Plan page 17