River restoration project encourages nature to take its course at the confluence of Wallowa and Lostine rivers

WALLOWA – Once the site of a Nez Perce fishing village, the confluence of the Lostine and Wallowa rivers is rich in both tradition and ecological function.

The confluence runs through farmland owned by Woody and Meghan Wolfe. A conservation easement held by the Wallowa Land Trust limits development along the river and restricts other parts of the farm to agricultural use only. Until this past summer, the river corridor has been left alone for more than a decade; outside of some low-impact restoration via volunteer labor – riparian plants have been added and existing ones protected with fencing, bird and bat houses were incorporated into the landscape, and weeds are pulled annually – all to maintain the health of the river and its banks.

To nudge the landscape along a little faster into a more natural state, the Nez Perce Tribe and Grande Ronde Model Watershed sponsored the Lostine Wetland and Side Channel Complex. Funding was secured the Oregon Watershed and Enhancement Board and Bonneville Power Administration to design a project that would improve floodplain connection and wetland conditions. The resulting project construction, funded by Bonneville for $228,496.49, entailed what Montana Pagano of the Nez Perce Tribe’s watershed division called a “light touch restoration approach.”

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Pagano said selected levees were breached at pilot channel inlets and outlets to restore the river’s flow. Off-channel habitat was created through alcove creation and side channel wood placement. Vertical post arrays made of wood were placed throughout both side channels and one of the alcoves to increase floodplain inundation and hyporheic exchange of groundwater and surface water in the porous space beneath and alongside the stream bed.

“In addition to the constructed large wood structures, dozens of downed cottonwood trees resulting from the intense August 8 windstorm are expected to further augment the restoration efforts implemented this summer in and around the river,” Pagano said.

After the excavation work was completed, contractors planted wetland plants and laid down grass seed to stabilize the soil, deter invasive weeds, and restore the riparian area’s native plant base. 

Pagano said, “The restoration will enhance local fish habitat for a variety of species including Chinook and coho salmon, steelhead, bull trout, Pacific lamprey, and other native aquatic and terrestrial animals.”

The work was completed during the instream work window of July 15 to August 15 in order to finish ahead of the Chinook spawning season. Pagano said the excavation didn’t deter this year’s returning adult Chinook.

“Immediately following project construction in August, an adult Chinook salmon was observed making a redd/nest in the upper reach of the project,” Pagano said. “This is evidence the in-river work did not dissuade spawning adults.”

In future years, Pagano said, the project is expected to further enhance spawning conditions in the mainstem of the river as well as increase juvenile habitat off-channel and along the river margins.

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