TWIN FALLS, Idaho — The Idaho State Department of Agriculture has launched its fourth annual treatment to eradicate invasive quagga mussels from a stretch of the Snake River near Twin Falls, taking a more targeted approach this year that keeps parts of the river accessible to the public.
The Twin Falls boat ramp is closed to boaters while the ISDA carries out its treatment. Downriver, the Centennial boat launch remains closed due to structural damage, leaving the Shoshone Falls boat launch as the only option close to town.
Joe Cain was at the Shoshone Falls boat launch when I spoke with him.
"I never did this before so we figured we'd jump out and try this today," Cain said.
Cain said his fishing experience on the river has changed since the quagga mussel discovery.
"I haven't had much luck on the river at all with the fishing though just with all the poisoning and stuff like that that's going on so," Cain said.
Quagga mussels were first discovered in the river in 2023, prompting a rapid response from state agriculture officials. Cain said he understood the necessity of the treatments.
"And I understand that it's important for them to do. They have to do it. You know what I mean, there's no other way for them to be under management," Cain said.
ISDA Director Chanel Tewalt said reduced mussel populations made a more focused treatment plan possible this year.
"The treatment in 2026 is anticipated to be much more targeted than what folks have seen from us in the past," Tewalt said.
Rather than treating a wide stretch of the river, the agency is concentrating copper treatment on two specific locations.
"Rather than treating all the way up .. very far up river from the Twin Falls Dam, we'll be very specific to that deep pool above the dam and then a deep pool above Shoshone Falls, but not the same as us moving copper treatment through power plants in Shoshone Falls in this whole system-wide treatment, it'll be very specific to copper being placed in those deep pools," Tewalt said.
The Twin Falls boat launch will remain closed until Sept. 5. The Shoshone Falls boat launch will then close from Sept. 6 through Sept. 13. The ISDA discourages swimming in the Snake River during treatments, but Centennial will remain open for kayaking and paddleboarding throughout.
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