In 2001, Coho salmon in the Russian River were pushed to the brink of extinction. In response, federal, state and local government agencies, along with non-profit groups began steps to save this endangered species.
Twelve years later the U.S. Army Corps of Engineers San Francisco District completed the Dry Creek Reach 15 Restoration Project at Lake Sonoma three weeks ahead of schedule. This portion of the larger six mile Dry Creek restoration is a $1.8 million project running along 1,600 feet of Dry Creek just downstream from the outlet works of Warm Springs Dam.
The district’s Russian River Coho Salmon Brood Stock program was successfully raising and releasing juvenile Salmon, but a National Marine Fisheries Service study found survival conditions in Dry Creek unfavorable after release.
“The purpose is to try and rehabilitate the Coho salmon and steel runs that historically came up the Russian River Watershed,” said Zak Talbott, the San Francisco District project quality assurance representative. “This particular area accounts for about a third of the flow that goes into the Russian River so there are a lot of salmon runs that have historically come up this way.”
The newly-completed secondary channel runs parallel to Dry Creek to provide low flow for salmon to rest, feed and spawn in, especially during summer and winter months when there is high release flow from the dam.
“So what we created the low flow channel enhancement area for was so that the fish can say, ‘Hey look there is a … smaller channel, the flow is a lot less severe, so we are going to hang out and go right instead of going up the main flow,’ ” explained Talbott.
After excavation, the channel was filled with two to four inches of cobblestone for armoring purposes and to form a habitat for fish to spawn in. Then large woody material was placed along the creek bed using excavated trees and boulders.
“What the trees are going to do is they are going to provide food for the fish. The water is going to break down the tree over time and create all these nutrients and microbes for the fish to feed on,” said Talbott.
Finally, willow spikes taken from trees cut down during excavation were planted every ten to fifteen feet along the project site. Willow trees are an essential plant species used for the stream restoration because they grow relatively fast and within three years they will be high enough to provide shade for the salmon swimming in the creek bed.
“Eventually these willows will grow up and create nice canopy for this low flow channel and provide some nice shade for the salmon as well as stream bank stabilization,” said Talbott.
The majority of land on Dry Creek is privately-owned, so cooperation with landowners is essential to meet the required six miles of habitat enhancement. The Reach 15 project, as part of the larger Dry Creek Demonstration Project, will be used to study how the enhancements work on a small scale, prior to construction of the complete six-mile enhancement required in NMFS’ Russian River Biological Opinion.