COUGAR, Wash. — A $300,000 acclimation channel built for spring chinook along the Muddy River south of Mount St. Helens has a problem: It’s so full of iron it can’t be used as part of the effort to return salmon to the upper North Fork of the Lewis River.
“We’re not abandoning it,” said Frank Shrier, principal scientist for PacifiCorp. “We’re trying to figure out how to make it work.”
PacifiCorp’s 50-year federal license to operate the three Lewis River dams calls for reintroduction of spring chinook, coho and winter steelhead upstream of Swift Dam.
In 2013, the utility built two rearing channels in the Gifford Pinchot National Forest upstream of Swift Reservoir. One is natural side channel of Clear Creek, the other a natural side channel of the Muddy River near the road No. 25 bridge.
The plan is to have young spring chinook spend about six weeks in late winter and early spring in the channels before they head downstream to the collector system at Swift Dam. At the dam, the fish are collected and trucked for release in the lower North Fork of the Lewis at Woodland.
But the approximately 600-foot-long Muddy River channel has too much iron.
“The iron depletes the oxygen in the water and it can get as low at 4 parts per million,” Shrier said. “That’s too low to put fish in. It’s not functional.”
Iron deposits are not uncommon around Mount St. Helens. Their rusty orange telltale sign can be seen a various locations.
The Muddy River channel has good quality water coming in at its upper end. At maximum capacity, it could rear 60,000 smolts.
“We ran flow through it all winter hoping to leach the iron out,” Shrier said.
It did not work.
Shrier said PacifiCorp has not given up on the Muddy River acclimation channel. A portable raceway pond may be tried at the site in coming years.
“We’re still figuring out what the heck to do up there,” he said.
The Clear Creek acclimation channel is capable of rearing 45,000 smolts, which are young salmon ready to head toward the ocean.
Low streamflow due to the minimal snowpack this past winter made the Clear Creek rearing channel unusable.
This spring, 67,000 young spring chinook were released directly into Clear Creek and another 33,000 into the North Fork of the Lewis River at Crab Creek.
Bids are due soon for a third acclimation facility, this one at Crab Creek, which flows into the North Fork of the Lewis River a mile or so downstream of Lower Falls.
At Crab Creek, a temporary tank lined with a rubber material will be used for acclimation. The tank will be dismantled and stored when not in use to preserve the aesthetic values during the recreation season.
The tank will have room for 15,000 smolts. Construction is planned in July and August.
