State officials say Idaho needs to keep its foot on the gas as they try to eradicate invasive mussels found in the Snake River three years ago.
Chanel Tewalt, who leads the Idaho Department of Agriculture, told a panel of lawmakers on Tuesday about the extensive steps her agency took this fall to knock out the remaining quagga mussels near Twin Falls.
Divers swam dozens of feet down to the craggy riverbed, spreading two different copper-based pesticides in nooks and crannies where Tewalt believes they evaded previous treatments.
“I don’t know what other human efforts are possible outside of concreting the bottom of the Snake River, which we have joked about many times and if you guys give us a vote we’d love to do that. But I don’t think anyone else would like it,” she said.
She says past treatments have been so effective that they’ve cut the scope of the program since the mussels were first detected in 2023.
“We have gone from about 10 miles of river treatment and then we halved it and now we’re down to a point where we’re treating literally 29 acres at the Twin Falls pool and just over 10 acres right above Shoshone Falls.”
If left unchecked, quagga mussels can clog up water and irrigation pipes that require costly repairs. They also edge out native species by competing for food and other resources.
Tewalt compared Idaho’s eradication program to California’s handling of a similar invasive mussel species found near the Port of Stockton in 2024.
While Idaho immediately treated the river with chemicals, California implemented a monitoring program. Two years later, those invasive mussels have now been detected hundreds of miles south near San Diego.
Tewalt said it’s a similar distance if the mussels were to spread from Twin Falls downriver to Lewiston.
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