(Boise, ID) Idaho needs to have a “critical conversation” about what out-of-state boat traffic looks like, Chanel Tewalt, Idaho State Department of Agriculture director, told Idaho legislators on Tuesday.
In a presentation to the House Agricultural Affairs Committee, Tewalt updated legislators on the department’s progress of eliminating invasive quagga mussels in the Snake River — a mission that has cost the state millions.
Quagga mussels were first discovered in September 2023 in the middle Snake River near Twin Falls, marking the first time quagga mussels had ever been found in the Columbia River Basin. While the department’s program to eliminate the mussels is well-resourced and efforts have reduced mussel populations in the river, Tewalt said the state must better communicate and enforce its strict watercraft inspection requirements to people visiting Idaho with boats.
“Idaho law says you will not haul a boat that has ballast water in it. You will not launch on Idaho waters if you are an out-of-state boater without having an inspection,” Tewalt said.
Tewalt said visitors from states with severe water issues, like Arizona or Colorado, don’t share Idaho’s conservation and agricultural priorities — which she said poses the greatest risk to the state.
“When we haul a livestock trailer through California, we know there’s different rules than when we haul at home,” she said, adding that many Idahoans traveling with their livestock in California have gotten fined.
“We need that same kind of concept, that same scaffolding,” Tewalt said. “When folks haul boats to Idaho, you need to know that we take this seriously.”
Idaho’s quagga mussel elimination plan biggest of its kind attempted in U.S.
At the beginning of her presentation, Tewalt discussed the history of Idaho’s invasive species program.
In the late 1980s, quagga and zebra mussels were detected in the U.S. for the first time. The species came from Central Europe, and quickly infested the Great Lakes. From that point, quagga and zebra mussels moved westward. In response, the Idaho Legislature in 2008 passed the Invasive Species Act calling on the Idaho State Department of Agriculture to set up boat check stations and implement an invasive species program.
“As much as they’re a problem in the Great Lakes, those things are not dependent on irrigation, and they’re not dependent on hydropower like we are in Idaho,” Tewalt told the committee.
The invasive mussels pose a threat to Idaho and the Columbia River Basin by:
- Clogging pipes used to deliver water, energy, agriculture, recreation and other uses
- Eliminating Idaho’s biological landscape
- Costing taxpayers millions of dollars in actual and indirect costs
Idaho’s quagga mussel elimination plan has been the biggest of its kind ever attempted in the United States, Tewalt told the committee. The department in fall of 2023 and 2024 used Natrix, a copper-based pesticide registered by the Environmental Protection Agency used to kill invasive aquatic species. The 2023 treatment, however, resulted in the death of thousands of fish, or six or seven tons of fish that had floated to the river’s surface. Among those fish were 48 white sturgeon, the oldest of which was 35 years old and up to eight feet in length, the Idaho Capital Sun previously reported.
“As heartbreaking as it is for people who have worked their whole lives in natural resources, the alternative is worse,” Tewalt told the committee. “Us doing nothing is worse.”
During the 2024 legislative session, legislators approved $6.6 million in the fiscal year 2025 budget for invasive species prevention efforts, with an emphasis on the Twin Falls area, the Sun previously reported. Meanwhile, the Idaho State Department of Agriculture spent $1.5 million on Natrix in 2023 and $2.1 million in 2024 after increasing its use by 40% across more areas of the river, department spokesperson Sydney Kennedy told the Sun.
The department has seen progress, but the effort is still ongoing.
“We knocked back the population, but finding any mussels is unacceptable,” Tewalt said, adding that the mussels can reproduce anywhere between 2,000 to a million eggs per year.
Nic Zurfluh, the bureau chief of the department’s invasive species program, presented alongside Tewalt. The department conducted larvae sampling in summer water temperatures to track the presence of the invasive species. And so far, he said department staff have not seen the substrate — or sediment, soil and other materials at the river’s bottom — fully covered with quagga mussels.
“We actually went through all 2024 without observing a single adult mussel,” Zurfluh said.
Zurfluh said the quagga mussel elimination efforts have required partnership between local, state and private entities. From working with hydrology experts, Idaho Power and the Idaho Department of Lands to out-of-state labs and the Simplot Company, he said the department has relied on their expertise and dedication, all driven by their commitment to natural resources and the environment.
Monitoring the mid-Snake River for quagga mussel larvae remains an ongoing effort, and water access from Pillar Falls to Twin Falls Dam remains closed. For updates on Idaho’s quagga mussel elimination efforts, visit the official Invasive Species of Idaho website.
This story first appeared on Idaho Capital Sun.