CLARK FORK, Idaho – Automobiles might play a role in the mating rituals of some humans, but for the better part of the last decade vehicles have also factored prominently in the spawning routines of Granite Creek’s trout population.
Lower portions of the stream were left impassable to fish after a 1996 flood. This meant that every day during spring and fall spawning runs, state workers would have to load egg-laden cutthroat and bull trout into a pickup for a short drive upstream. After the eggs were deposited and fertilized, and the fish had rested a bit, they would swim downstream and into a trap to await another pickup ride home to Lake Pend Oreille.
Last month, 3,000 feet of the creek were completely rebuilt. The fish will soon be able to swim between their spawning grounds and the lake – the same way they have since icy glacial waters flowed through these parts thousands of years ago.
From the wooden bridge that crosses Granite Creek, it’s nearly impossible to detect anything different about the stream. Flowing out of a narrow, forested canyon, the water is clear as gin, except in deeper pools where it takes on the hue of emeralds or mint mouthwash. The water tumbles over boulders, fallen logs and stumps on its way to Lake Pend Oreille.
During a visit this week, the fixes to the stream became apparent only after being pointed out by Chris Downs, a fisheries biologist with the Idaho Fish and Game Department. Downs helped supervise the $180,000 project, which was paid for largely by Avista Utilities, with help from the state, the U.S. Forest Service and Trout Unlimited. Avista funds a variety of fish and wildlife habitat improvement projects in the area as part of its agreement to operate hydroelectric dams on the Clark Fork River.
The first sign that Granite Creek is different from a typical trout stream are the faint traces of bulldozer tracks in the streambed. During the six-week construction project, the stream was diverted into a side channel, Downs said. This allowed engineers to make the proper channel alignments and to position logs, root wads and boulders. What appears to be haphazard placement of logs and rocks is actually the result of a plan that attempts to mimic the complexity of nature, Downs said.
Downs pointed to a fallen log positioned at a 20 degree angle off the bank, with a 3 percent dip – a design meant to direct water toward the center of the channel. “There’s a lot of science behind it,” he said.
A bit farther upstream, the creek crosses a wide floodplain where some of the creek’s recent trouble started. It was early in 1996 when a rainstorm fell atop a thick blanket of snow, unleashing a torrent of water. The water smashed into exposed banks along the floodplain, picking up tons of rock and gravel – in addition to the sediment already being carried in the floodwater from old logging roads higher in the watershed. The pulse dumped up to four feet of sediment in some places, causing the stream to carve a new channel.
“It jumped its tracks,” Downs explained.
The new channel was braided and made a direct plunge for the lake. There were no more deep holes or meandering bends. This meant the stream went dry in summer, thwarting late summer spawning runs of bull trout – a species that is threatened with extinction. Lake Pend Oreille has one of the nation’s strongest remaining populations of the species, which spawn only in the coldest, cleanest, most secluded waters. Of the 17 bull trout spawning streams that flow into the lake, Granite Creek is among the most important for sustaining the species, Downs said.
Trapping and trucking the fish seemed to be the best quick fix, but it wasn’t a long-term solution, Downs said.
Restoring the creek to a single channel, however, was not as easy as simply digging a trench. The new stream had to be designed to absorb the tremendous energy of occasional floods. It also needed hospitable pools, riffles and bends. Experts studied stream flow charts and maps to create a pathway that would have the best chance of staying wet through the driest months, while still absorbing the pulses of spring floods, Downs said, while walking through the cool, dark, earthy-smelling cedar forest that grows alongside the creek.
At a bend in the stream, Downs pointed to a pile of logs.
“That’s an engineered debris jam,” he said. “They create great fish habitat right out of the box.”
The logs absorb energy from the river. They slow the water, causing it to roil and dig deep, fish-friendly holes full of cold water. Crews built the jams by anchoring layers of logs and root wads deep in the ground.
“This is one of my favorite debris jams,” Downs said, pausing. “It makes me kind of sad that I have a favorite debris jam, but I do.”
Before work could begin on the stream, the trout needed to be evicted. Portable electro-shock devices were used to temporarily stun the fish out of hiding areas so they could be moved to safety. Downs said he was impressed by how many bull trout remained in the broken stream. “We stopped counting at 1,500,” he said.
A nearby resident, Keith Ellingson, said he watched in amazement as crews rebuilt the trout stream.
“It really impressed me. It really did,” he said, taking a break from riding his four-wheeler. “But there’s so much of the work you just don’t see.”
Not far away, a spotted frog sat partially submerged in the rebuilt creek, basking in the late summer sun. The project was only recently completed and the stream remains largely empty of life. Unlike a typical trout stream, the undersides of boulders are not crawling with insect larvae.
The bugs will return soon, Downs said. The trout should also be coming back before too long, no longer needing to hitch a ride in a pickup as they make their way to ancient spawning grounds in the gravel upstream.
“There’s a whole lot of things going on in streams that we don’t understand,” Downs said. “We just try to provide the basic physical template and let nature do the rest.”
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