A project to restore floodplain habitat in a stretch of the upper Grande Ronde River in Northeastern Oregon is paying off with improved flows, decreased bank erosion, improved water temperatures in both winter and summer, and the potential to increase production of wild juvenile salmon. A representative of the Confederated Tribes of the Umatilla Indian Reservation reported on the project, known as Bird Track Springs, at the February meeting of the Council’s Fish and Wildlife Committee.
The Bird Track Springs project is located at 3,100 feet elevation along the mainstem Grande Ronde River between river mile 144.7 and 146.1 along State Highway 244. The project includes both national forest and privately owned land. Over time, human activities, notably logging, altered natural processes in the river, including disconnecting historic floodplain habitat from the main channel of the Grande Ronde. As well, the impacts included a lack of woody debris and other material that contribute to habitat complexity that can slow the flow and create pools where juvenile fish can rest, feed, and rear, and water temperatures that were too warm for juvenile salmon.
Because of the impacts, the project area and other river reaches in the middle part of the Upper Grande Ronde, which are within the Tribes’ historic area, were incapable of supporting the Tribes’ First Foods policy. So the Tribes formed a unique partnership with state, federal, and local agencies including the Grande Ronde Model Watershed, and local land owners, to address the problems in the Bird Track reach. The goal was to improve river function and habitat for the benefit of Chinook salmon, steelhead, bull trout, lamprey, and other species.
The project aimed to increase the frequency and duration of floodplain inundation, improve the connection between the river and cold groundwater, create more pools and side channels, add woody debris to the river, and plant new native vegetation. The project results included reconnecting 135 acres of historic floodplain to the main channel of the river, constructing 9,500 feet of new channel, creating 17 large pools in the mainstem river and 47 smaller pools in side channels, adding more than 500 woody debris structures to the project area, and improving 3,700 feet of riverbank.
“We’ve seen consistently colder water in the side channels – much cooler in the summer, and better able to support anadromous fish,” said Allen Childs, Tributary Habitat Lead for the Umatilla Tribes. “Chinook spawning in the reach is generally pretty positive, a pretty extensive use of the area. From our perspective, the flood plain project performed admirably. We saw some localized erosion, but that was all; the wood performed well.”
He said the project demonstrates the importance to salmon reproduction of improving floodplain habitat. Re-engineering the main channel of the river will lessen the impacts of periodic large floods and winter ice flows, he said. The project work began in 2018 and was completed in December 2019, and since then biologists and engineers have been monitoring how fish use the restored floodplain and how well the alterations to the river channel are performing.
“What we’re really excited about is the upward trend of the groundwater elevation,” Childs said. “We’ve seen an increase of two to three meters, and this is important for rehydrating the floodplain. The groundwater is super cold, and the temperature is pretty uniform. The more groundwater you can get to supply the channel, the better chance we have to improve conditions for salmon.”
Before the project, juvenile salmon were quickly carried downriver by the current, but now with the current slowed and more pools available, fish are able to stay in the cold-water habitat longer, and that improves their chances of surviving to return and spawn as adults.
Two consecutive floods occurred during February and March 2020, with the March flood documented as largest of record. The project floodplain absorbed the events with minimal effect, evidence of the success of the restored floodplain processes.