The Return of the Clark Fork Delta

How an Idaho community is restoring an ecologically and culturally significant wetland that was once written off as lost.

On a January day in 2015 just warm enough to have thawed the ground, the Clark Fork River delta looked like a freeway construction site. Hard-hatted workers in high rubber boots drove mud-spattered pickups among piles of gravel and fill. Excavators, like foraging dinosaurs, reached their maws deep into shallow channels and came up with dripping loads of dirt, which they dumped on top of piles of rock.

photo of clark fork delta
Prior to a massive restoration project, the Clark Fork Delta was losing 12 to 15 acres of riverbank every year to erosion. Photo courtesy of Kathy Cousins / Idaho Department of Fish and Game.

Katherine Cousins, a mitigation staff biologist with Idaho’s Department of Fish and Game, was leading a tour through this muddy morass at the easternmost end of Idaho’s Lake Pend Oreille.  The visitors — potential volunteers who would help her rebuild the delta — followed her like a mother hen, stopping occasionally and sinking with her into the mud. She explained that as spring came the water would drain, leaving land on which she hoped they would help restore native plants. Although the mud would be gone, she admitted somewhat sheepishly that there might be mosquitoes.

Four years later, the islands the excavators created and the volunteers planted are doing their job of stabilizing the delta. Weather in the interim has included one particularly early spring runoff followed by unusual heat and drought, a historic storm that threw logs 30 feet up onto the re-created land, and a major flood that put the whole project under water. But before-and-after photos show that the newly built landscape has survived it all.

Cousins first saw this dying delta when she came to work in the Idaho panhandle in 2004. She recognized immediately that something would have to change soon if it was not to be lost forever. Twelve to fifteen acres of riverbank were collapsing and washing away each year, taking with them wildlife habitat, recreational opportunities, and cultural resources for the Kalispel people, who hunted, fished, and gathered reeds here for millennia.

What had caused this loss? “It’s complicated,” says Cousins with the practiced patience of an individual who has repeated this explanation many times. The sediment, rocks, and cobble that once arrived with high water flows every spring from the Clark Fork River are now trapped by the Cabinet Gorge Dam and other dams upstream. In addition, the Albeni Falls Dam on the Pend Oreille River, the outlet to the lake, has kept the lake level higher each summer than it was before the dams were built more than half a century ago. Waves across the long fetches from the northwest and southwest ends of the 42-mile lake have taken their toll on what is left. Pieces of the bank have slumped off when the water was drawn down each year, and when the lake came up again each spring, these pieces washed away.

In addition to the loss of land, a single species of plant, reed canarygrass, had invaded what remained. “Reed canarygrass is good at surviving in wet ground and adapting to highly disturbed areas with altered hydrology,” says Cousins. But it isn’t the right height at the right time to provide nesting birds with the cover they need. The willows, cattails, sedges, and forbs that once supplied that cover were outcompeted by the reed canarygrass.

The damage was no surprise. Wildlife mitigation funding associated with the dams’ construction was to be spent on parcels of wetland elsewhere to account for the loss of the wetlands at the mouth of the Clark Fork. “The delta had been written off,” says Cousins. No one thought it could be brought back.

Cousins proved them wrong. First, she completed a successful rehab on the much smaller Pack River Delta across the lake in 2009 to prove her concept. With that success, the State of Idaho was able to procure a letter of agreement with the Bonneville Power Administration, which manages the dams, to repurpose some of the dedicated mitigation funding. That money funded the work in the mud that volunteers toured in 2015.

What worked? During the winter months, when the dams keep the water level low, heavy equipment put large boulders in place to create barriers that would protect the shore from pounding waves. Excavators put fill on top of this, and then tens of thousands of willow poles were placed on top of the fill. Finally, a bulldozer covered those up with more dirt and rock. The willow poles sprouted, and their roots helped hold the new soil and rock in place. Volunteers harvested and delivered thousands of additional willow poles and inserted them into the soft soils.

But Cousins also needed to reestablish native plants on top of this rock-willow sandwich and on newly raised ground. To this end, she enlisted volunteers from the local native plant society, who developed a list of appropriate species with input from local Kalispel people. While she admits that it’s unlikely the reed canarygrass will ever be totally eradicated, the newly inserted natives will at least be able to compete with it, and to provide the cover and food that nesting waterfowl need.

The small group that slogged through the site with Cousins ballooned into a force of nature in the spring and summer of 2015. Volunteers from the Kaniksu Land Trust, Kinnickinnick Native Plant Society, Idaho Conservation League, and Bonner County Master Naturalists, along with students from a half dozen schools, put in 1,467 hours planting 20,813 native shrubs and trees. Over the summer, young people with the Northwest Youth Corps added 79,736 more.

photo of clark fork delta
Volunteers have already restored hundreds of acres of habitat in the Clark Fork Delta. The remainder of the delta will be restored in the coming years. Photo courtesy of Kathy Cousins / Idaho Department of Fish and Game.

Jim DuBuisson, a retired social worker who often kayaks in the delta, was a member of this effort. He had noticed the banks of the islands were getting steeper, and he was intrigued by the idea of the project. If there were mosquitoes, they don’t stand out in his memory. “I actually hit a couple of really nice days,” he recalls. “We worked as early as we could, so we could get it in before the summer heat, after the water was up, but before it got hot.”

Of 2,000 acres lost, about a third has been restored. It’s a big enough success that BPA was convinced last August to fund the complete restoration, and they will also fund an ongoing operational stewardship so that Cousins and her successors can continue to fight the reed canarygrass.

So the big machines will return next winter to create more rock/willow sandwiches as well as bendway weirs in the adjacent channels. The weirs — rock structures that will be underwater at full summer pool — will help prevent future erosion by directing stream flow away from the banks of the channels in the delta. Work will continue with what Cousins calls “another 100,000-plant effort” to complete protection by 2022.

Cousins will be looking for volunteers again, not only to complete the restoration but to help monitor the project to make sure the land is staying in place as planned and that the plant diversity continues to improve. We’re on the right track, but we’ve just started,” she points out. To truly replace the wildlife habitat the delta once provided, “We’ve still got a long way to go."

Given her track record, it’s not difficult to envision a fully restored delta, filled with native plants, thriving bird populations, and recreating locals in the not-so-distant future.

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