When erosion threatened a National Register-eligible archaeological site on Idaho’s Pend Oreille River, a Seattle District, U.S. Army Corps of Engineers’ team went the distance to stabilize the bank and minimize construction impacts to adjacent wetland habitat.
“This is an important project because once we lose an archaeological site it’s lost forever, along with all the information it contains,” said Kara Kanaby, project archaeologist.
The bank stabilization work itself was pretty straightforward – armor 2,000 feet of shoreline with 5,000 tons of riprap and install a willow lift about one foot above the Carey Creek Wildlife Management Area ordinary high water line. Getting to the construction site, however, presented a challenge.
After efforts stalled to gain right-of-way access over private land, the team was forced to select an alternate route.
“In the end we decided to use a field on Kalispel lands,” Kanaby said. “It wasn’t our first choice because of the distance we had to cross, but working with the Kalispel Tribe was great.”
Had the Corps gained the desired real estate easement, construction crews would’ve used existing paved roads before crossing about 60 feet of private land to access the site. With the alternate route, however, crews would have to traverse nearly a half-mile over a field and wetland habitat.
To avoid damaging the landscape with heavy equipment, construction work occurred during winter months when the ground was frozen and the team continued looking for inventive solutions to mitigate damage even further.
“We were still concerned about leaving deep gouges and ruts in the land and then having to come back to remedy that,” Kanaby said. “So the team brainstormed and came up with wetland mats.”
Resembling heavy-duty wooden pallets, the wetland timber mats were lined up end-to-end over 2,600 feet, creating a path for construction equipment and providing a protective layer for the ground beneath.
“They worked wonderfully! I was there when they were being removed and the grass was just folded over,” Kanaby said. “There were a couple of wet spots, but no deep gouges or damage to the ground. I’d definitely use them again.”
After completing bank stabilization work in January, Corps representatives returned in April to plant 1,500 native shrubs intended to attract pollinators such as bees and hummingbirds to the wetland habitat.
The plantings included a special gift from Idaho Department of Fish and Game (IDFG) which handles the site’s wildlife management – 21 showy milkweed plants.
“One of the folks from IDFG is a huge monarch butterfly fan and grows his own milkweed which is a food source for butterflies,” said Albeni Falls Dam Natural Resource Specialist Betsy Hull. “So we took those gifted plants and created a milkweed patch on the backside of the stabilization.”
In addition, Albeni Falls Dam purchased 200 common camas plants to supplement naturally-growing camas on the 56-acre wetland site.
“Carey Creek is where Tribes would gather and cook camas, a traditional staple of the Native American diet,” Hull said. “They still use the area as a meeting site so we wanted to add some camas back to the landscape. Jill Wagner and Nick Kager of the Coeur d' Alene Tribe of Indians volunteered their time to help with the effort and planted the camas plants.”
The $600,000 project was funded by Bonneville Power Administration (BPA) through the Federal Columbia River Power System mitigation program.
Throughout planning and construction, the Seattle team coordinated with BPA, IDFG, Idaho State Historic Preservation Office, the Kalispel Tribe, Coeur d’Alene Tribe, Kootenai Tribe of Idaho and the Confederated Salish and Kootenai Tribe of the Flathead Indian Reservation.
“It was really fulfilling to protect such an important archaeological site and come up with a unique plan to safeguard this important cultural landscape while doing it,” Kanaby said