CAVE JUNCTION — Bulldozers and excavators this week are replacing centuries worth of floods and fires to restore an abandoned mine site on a major Illinois River spawning tributary.

CAVE JUNCTION — Bulldozers and excavators this week are replacing centuries worth of floods and fires to restore an abandoned mine site on a major Illinois River spawning tributary.

U.S. Forest Service officials and Illinois Valley watershed aficionados are rebuilding almost a half-mile of a side-channel along rural Sucker Creek that was left dry when placer miners diverted that part of the flow in the 1980s in their quest for gold.

Gone will be huge swaths of fine sands and berms that pockmarked the old KOLA mine site east of Cave Junction.

In their place will be a meandering side-channel with fresh spawning gravel and myriad refuges for wild salmon such as coho, which are listed as endangered under the federal Endangered Species Act.

"This is an opportunity to build a coho factory," says Ian Reid, a fish biologist with the Rogue River-Siskiyou National Forest, who is working on the project.

"We could wait 300 years for nature to do this," Reid says. "We're just speeding up the process. With coho being listed (as endangered), time is of the essence."

The project is the latest of several either completed or envisioned for Sucker Creek as part of an overall strategy for restoring habitat for wild coho and other native fish in the basin.

"Projects like this are going to be how we do it," Reid says.

The Illinois basin, which is a sub-basin of the Rogue River basin, produces about one-third of all Rogue basin wild coho, Reid says. Of the Illinois's coho component, about 20 percent annually call Sucker Creek home.

This particular reach of the stream, which is about 12 miles east of Cave Junction, also supports wild chinook salmon, winter steelhead, cutthroat trout and Pacific lamprey.

The project is being done by contractors and overseen by the Illinois Valley Watershed Council, which has joined forces with the Forest Service to improve and protect the Sucker Creek basin.

By creating the new side-channel and diverting about 10 percent of the creek's water through it, flows will slow down and disperse their energy instead of creating erosion problems downstream, says Kevin O'Brien, the watershed council's coordinator.

"It'll be great to put this thing back together," O'Brien says. "Sucker Creek needs a lot of help, and this helps put the creek back into a position to do what it wants to do."

This stretch of Sucker Creek was the site of hydraulic mines in the 1800s, and placer miners returned in the 1980s, building an open area for washing gold out of excavated sand and stones. The site included a settling pond to capture silt, and that pond remains.

To build it, miners used boulders to divert the creek away from the site. But the site was withdrawn from mining in the early 1990s and is not now open for claims, Reid says.

For about three years, Forest Service crews have been planning this project, partly because it is one of the few pieces of local Forest Service land where significant improvements can be made for coho, which tend to spawn lower in tributaries than other migrators like steelhead, Reid says.

Contractors cut the new stream channel through the trees and brush, creating intricately designed riffles and pools to control flows. Alcoves will be cut into the sides of the channel, and the old pond will be tied into the system before it flows back into the main creek channel about .04 of a mile downstream.

The design will help cool the stream and provide habitat for infant salmon and steelhead fighting the heat in summer and avoiding freshet events in the winter, Reid says.

The sand will be replaced by clean gravel from a nearby mining contractor and added as prime spawning habitat for wild coho, Reid says.

Construction likely will be completed next week and it will be followed by workers planting alder, cottonwoods and other native vegetation to strengthen the new channel's banks and help provide shade in previously open areas.

The new channel will be ready when wild coho return to Sucker Creek in late fall in their spawning colors, Reid says.

"Come December, this place should be loaded with red fish," Reid says.

Reach reporter Mark Freeman at 776-4470, or e-mail mfreeman@mailtribune.com.