An air tanker fighting a wildfire in central Oregon accidentally dumped up to 2,000 gallons of retardant into Fall River, killing nearly all the fish in a 4-mile stretch, officials said.
The retardant, which was dropped Thursday, also made its way into the Deschutes River above Sunriver, officials said Friday.
The retardant killed hundreds of hatchery-bred rainbow trout, native band trout, white fish, and brown and brook trout, said Clair Kunkel, program supervisor for the Oregon Fish and Wildlife Department.
Wildlife officials still are determining what ingredients in the retardant were toxic to the fish.
The main ingredient in the retardant is ammonium polyphosphate, a commonly used agricultural fertilizer, according to the Deschutes National Forest. The substance also contains tiny amounts of clay thickeners, corrosion inhibitors and coloring.
"We realize this happened under emergency conditions, close to residential areas," Kunkel said. "Folks were fighting fire in the best way they could at the time. It's an unfortunate accident."
The tanker was fighting a one-acre wildfire that erupted Thursday about a mile southeast of the Fall River fish hatchery when it dropped the load. That blaze was under control Saturday, with no damage to homes.
Steve Avery, a fisherman, said he was on the Fall River at about 3 p.m. when the retardant flowed downstream and fish started dying.
"The water just went from crystal clear to opaque red," he said. "We saw dead fish, everything from 8-inch hatchery redsides to 24-inch brown trout. It was just awful."
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