Oregon Department of Fish and Wildlife: JOHN DAY, Ore. — According to the Oregon Department of Fish and Wildlife, a severe thunderstorm caused a flash flood in a tributary of the John Day River near Mitchell earlier this week, killing an estimated 4,000 smallmouth bass on a remote four-mile section of the river. Numerous other fish species including bass, suckers, pikeminnow and carp were also lost, but remarkably no dead channel catfish, steelhead or salmon were found.
The fish kill was first discovered by rafters who reported it to the Bureau of Land Management (BLM) on Wednesday, August 5th after finishing their float trip. The following day an investigation by biologists from ODFW’s John Day district office, the Confederated Tribes of the Warm Springs Indian Reservation and BLM revealed the fish losses resulted when low, warm water conditions suddenly changed to a high, silt-laden flood robbing the water of all oxygen. Because live fish were found immediately above and six miles below the affected site, fisheries managers expect fishing in the area will return to normal by next year.
According to information received from the United States Geological Survey, flow monitoring recorders revealed that within a five hour period from 7:00 PM to midnight on August 1, flows on Bridge Creek spiked from approximately 1.8 feet to six feet, and then quickly dropped back to approximately 1.6 feet. Bridge Creek is a tributary to the lower John Day River at river mile 135. The silt-laden flow from Bridge Creek did not reach the John Day River until about 6:00 AM Sunday.
According to Jeff Neal, ODFW’s fish biologist in John Day, summer thunderstorms have precipitated similar fish kills on the John Day River in past years. “These storms can be much more devastating if they occur on stretches of the river where salmonids are present, but this area was too far down in the river system for any salmon or steelhead to have been affected”, said Neal.
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