“Flushing” for restoration
November 2, 2014
Crews from Wildish Construction Company moved over 110,000 cubic yards of gravel as they worked to recreate habitat for fish as part of the Coburg Aggregate Reclamation Project. Until the McKenzie River Trust purchased this 56-acre parcel in 2010, the site was mined for sand and gravel. The mining left behind steep gravel pits with few places for native plants to take hold.
The CARP site is in an active side channel of the Willamette River. “We call this area the historic McKenzie River channel, because the main channel of the McKenzie River flowed right through here before the big 1964 floods,” according to Chris Vogel, who has been the manager of restoration efforts at Green Island for six years. The flooding moved the confluence of the McKenzie and Willamette rivers to where it is today, just south of Green Island. That channel has water year round, even more in the winter.
In the past, the side would channel fill up and then empty out, at least a couple times a year during high water events. During that flushing process water in the ponds, as well as creatures living in them, were washed down the channel. In a natural area, this flushing provides a huge range of benefits for fish and wildlife.
“Before restoration, when that historic McKenzie River channel filled up, it would overtop into the pits. Lots of fish - both native and non-native - would get trapped until the next high flow,“ says Vogel.
The fish didn’t have a way to escape back into the channel as the water dropped. So, stranded, the fish lived their lives in the pits. “More frequent flushing will get them out,” says Chris.
The solution was to use heavy construction equipment to grade the slopes to a more natural rise of one foot up for every ten feet out. This summer workers moved 125,000 cubic yards of gravel to create new slopes along with entry and exit points for the ponds to be much friendlier to native Willamette spring Chinook salmon, Oregon chub, and other fish and wildlife.
A new side-channel bypasses gravel ponds at the Coburg Aggregate Reclamation Project on Green Island, allowing fish to go around the pits in high water events and continue on down the Willamette River system.
This winter thousands of willows and other native trees and shrubs will be planted along the pond edges. As the plants grow up, they’ll offer fish plenty of places to hide from predators.
“We’re always looking for ways to give life to the river,” says Joe Moll, Executive Director of MRT. “This is one of the best investments we can make to do that.”
Image above: Photo by Chris Vogel Heavy equipment was used for years in the gravel pits on Green Island. This summer workers were busy reshaping the landscape to make water flow more naturally.
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