Restoration helps river heal from gravel mine, flooding
On the north side of the Clackamas River just upstream from Barton Park, bulldozers grind their way over bare dirt, and a giant mechanical sorter separates boulders from cobble and gravel. In the distance, a giant pile driver plunges huge, sharpened logs deep into the earth.
The machines are moving thousands of yards of earth and rocks to restore and stabilize the rivers floodplain and north bank, construct logjams to create fish habitat and excavate a channel to reconnect a small tributary to the Clackamas River.
This summers construction work on the north side of the Clackamas River is the second stage of a large-scale restoration of River Island, a 240-acre natural area that includes wetlands, oak savanna and upland and riparian forests. Last year, restoration work was completed on the south side of the river.
The restoration work is paid for with money from voter investments in regional parks, trails and natural areas and from Portland General Electric.
Decades of gravel mining and a major flood in 1996 changed the course of the river in this area and damaged habitat for multiple species, including salmon.
The river is actively changing here, says Brian Vaughn, senior natural resources scientist at Metro. How do we work with the river, anticipate where it wants to go and help it heal itself over time?
Newly installed large logjams shore up the riverbank, and gravel helps to rebuild the floodplain. The logjams will increase the complexity and roughness of the floodplain, allowing it to slow floodwaters and capture nutrients and sediments. The piles of logs also provide shelter for fish, birds, amphibians and mammals.
The work also creates backwater habitat that young salmon rely on for rest from fast-moving waters.
Native species benefit
Just beyond the floodplain is a wetland with several ponds left from the mining operation. The wetlands are an important habitat for native western painted turtles, salamanders and frogs. Logs will be placed into these ponds for the turtles to bask on.
Turtles are cold-blooded, says Elaine Stewart, a senior natural resources scientist at Metro. They hibernate, spending months underwater partially buried at the bottom of a pond, slough or quiet backwater.
Another major component of this summers work is reconnecting Goose Creek to the Clackamas River. The 1996 flood caused the river to change course, bypassing its confluence with Goose Creek, Vaughn says. Steelhead and coho salmon that once spawned there could no longer enter the creek as sediment filled the area.
He points to a deeper, narrower channel that is being excavated along the former Clackamas River bed to allow salmon and Pacific lamprey to enter Goose Creek once again. The redesigned former river channel will connect seamlessly to the mouth of Goose Creek and maintain the flow of cool water that supports native fish.
Beavers likely will return once construction is finished in October, Vaughn says.
This winter, more than 100,000 native trees and shrubs will go into the ground along the north bank of the Clackamas, in the floodplain and along Goose Creek. The plants will help prevent erosion, provide food and shelter for animals and provide shade to cool the water.
Charlie Christensens farm is right across the river from the work site. Hes been there since 1976, and his wifes family has farmed there since the 1800s.
Despite the short-term noise, he says he knows that the project is improving the bank and floodplain and making the river less destructive. Hes also enthusiastic about the prospect that salmon may return. His wifes grandfather and great-grandfather used to catch salmon, and they had a smokehouse right by the river, he says.