Chinook appear OK after Eagle Point canal failure
Biologists believe the Rogue River's wild spring chinook "dodged a bullet" last week when a slide of clayish mud was unleashed by a failed irrigation canal.
Stream surveys so far have shown that the intense plume of reddish clay that hit the river Oct. 2 has not killed any chinook egg nests, called redds, along nine miles of lower Big Butte Creek and about two miles of the Upper Rogue immediately downstream from the creek's mouth.
That area covers a major portion of spawning grounds for wild spring chinook, a depressed run of Rogue salmon whose needs trump others when it comes to habitat management, angling rules and Lost Creek Lake water management.
"We may have dodged a bullet, but it still warrants more investigation," said fish biologist Jay Doino of the Oregon Department of Fish and Wildlife.
About half of this year's wild spring chinook had spawned in the mainstem upper Rogue and lower Big Butte Creek before the Eagle Point Irrigation District canal on private timber land failed in a landslide off Cobleigh Road.
About 100 feet of the canal collapsed, and 86 cubic feet per second of water scoured the hillside and flowed across Cobleigh Road before dumping into the creek.
Heavy clay soils carried by the water had the potential to settle on top of the nests and smother the incubating eggs.
But surveys done so far have turned up only "a very fine layer" of red clay on the redds that does not appear to have killed them, Doino said.
More surveys are planned this week, Doino said. The clay was thickest on the lower stretch of Big Butte Creek and was visible in the Rogue down to a location called The Pump Hole, less than two miles from the creek's confluence with the Rogue, he said.
The turbidity of the water at Dodge Bridge, where Highway 234 crosses the Rogue near Eagle Point, was 25 times higher after the slide than before.
"The bottom line is we're still not sure what the impact on redds is from this event," Doino said.
The hillside uphill of the canal apparently gave way and slide down, taking out about 100 feet of the main canal. The ditch feeds water to 560 EPID customers, who collectively irrigate 8,260 acres, district manager David Ford said.
The district has hired contractors to pinpoint a cause, and repairs began the day after the slide.
Ford said he expects the repairs to take a month to complete.
"We want it repaired before the winter rains hit," Ford said.
Ford declined to speculate on the repair costs, but said the canal will be up and running in time for next year's irrigation season.
EPID patrons lost access to their water when the district shut off flows into the canal after the slide. The district had planned to end its irrigation season Friday.
Reach reporter Mark Freeman at 541-776-4470, or email at firstname.lastname@example.org.