Biologists are relying on computer simulators and engineered earthen structures to return natural features to a stretch of lower Little Butte Creek that hasn't been itself for more than 50 years.
A series of geomorphic riffles, strategically placed boulders, engineered logjams and structures called "vegetative soil lifts" have been designed to restore the creek to its meandering, multichanneled streambed through a stretch of the Denman Wildlife Area.
The features, along with a large earthen "plug" to divert the creek away from its current artificial channel, are the latest designs for this restoration project meant to benefit the creek's native salmon.
And the irony of intensely engineered naturalness is not lost on Oregon Department of Fish and Wildlife biologist Jay Doino, who believes helping what he calls "a pretty damaged" stream return to its old channel is worth the tricky engineering needed to get there.
"We don't want to turn this into a computer-generated natural feature," Doino says. "At the same time, we want to set it up so it can develop over time to what it was, without exploding in the process."
Created by a Corvallis stream-restoration expert, the design is being used by Doino and others working to raise the $550,000 needed to restore the lower creek habitat through the state-owned wildlife area at the creek's confluence with the upper Rogue River.
The latest pitch will come Friday before the Oregon Restoration and Enhancement Board, which has been asked to supply $75,000 toward the project.
Brian Barr, habitat-restoration project manager for the Ashland-based National Center for Conservation Science and Policy and the pitch-man before the restoration board, says the design is meant to create long-term habitat changes.
"When it's built, we won't have to go back in 20 years and redesign it," Barr says. "It's something that can maintain itself. That's definitely a selling point."
Doino already has pending grant applications of $350,000 to the Oregon Watershed Enhancement Board, and a $35,000 request before the Blue Sky Fund overseen by the Nature Conservancy.
Another $100,000 could come from NOAA-Fisheries Restoration Center, Doino says. The project could come to fruition as early as next year, he says.
"Everybody seems supportive," Doino says. "There's more work to be done, and I think it's going to be cool. But it's all fundraising now."
The original creek channel is a meandering S-curve through the wildlife area, and that feature was blamed for erosion occurring there during the 1955 flood.
In the late 1950s, the current 1.3-mile, straight-shot channel through the wildlife area was created by bulldozing a set of earthen berms that rise up on the creek's southern side, blocking water flows to Denman fields during all but the highest of flood events.
The unnatural alignment creates high-velocity flows during winter storms and forces the creek to scour downward instead of feathering outward into the floodplain.
Plans are to break through the eastern part of the berm and use that dirt to block the 1950s channel and divert all the creek water to where it once flowed.
Within the new reach, designers plan a series of glide-riffle-pool steps created artificially by meticulous structures created by rocks, dirt and logs.
Geomorphic riffles would control the downward gradient of the flows so the creek no longer will scour down to bedrock. Engineered log jams placed on the outside turns of the bends will stabilize the bends and curb erosion.
So-called "vegetative soil lifts" built of strategically placed logs and dirt will be worked into the project to stabilize disturbed banks and encourage native vegetation over time to fortify the stream-side riparian area.
"It might look like over-engineering, or overkill," Barr says. "But the point is to get it where Little Butte Creek finds the original channel as the path of least resistance and stays there."
Once done, the creek would reconnect to its original floodplain. Doing so would help juvenile salmon — including wild Rogue coho salmon, which are listed as a federally threatened species — survive flood events by riding the ebb and flow of the creek waters within the floodplain.
Over time, the new channel should provide spawning habitat for wild fall chinook salmon, but flows likely will remain too low for spring chinook to take advantage of that gravel, Doino says.
Also, the lower and slower flows within the meandering stream will have a better chance to come into contact with cooler groundwater, which could help ease future effects of climate change to this creek, Barr says.
Reach reporter Mark Freeman at 776-4470, or e-mail firstname.lastname@example.org.