Invasive mussels in Snake River pose ‘serious challenges’ to Idaho

Mia Maldonado

(Idaho Capital Sun) One week after implementing its rapid response plan after confirming the presence of invasive mussels, the Idaho State Department of Agriculture continues to urge recreation users to stay off the water in the Snake River near Twin Falls.

On Sept. 18, the department said it found multiple samples of quagga mussels in the Centennial Waterfront Park area in Twin Falls. Since then, it has implemented multiple measures to contain the species and treat the water in the area.

“For the public’s safety, the safety of ISDA staff and to minimize potential movement of quagga mussels, the ISDA has closed off public access to the Snake River between Niagara Springs and Twin Falls,” the department said in a press release Tuesday.

Idaho State Department of Agriculture spokesperson, Sydney Kennedy, said in an email Monday that people entering the Snake River on boats, paddleboards and kayaks over the weekend hindered the rapid response plan.

As part of the rapid response plan, the department staff is working to survey the physical range of the impacted area by collecting hundreds of samples from the Snake River for quagga mussel larvae.

Kennedy said the state is responding aggressively to the issue, including offering hot wash stations to decontaminate boats, rafts, kayaks, paddle boards, waders and decoys.

There are two hot wash stations in the area at the Twin Falls Visitors Center and Twin Falls County West. Anyone who has been in the mid-Snake River in the last 30 days is required to stop at one of the two locations and get a free hot wash, according to the press release.

Why are quagga mussels in the Snake River a problem? 

Lloyd Knight, the department’s deputy director, told the Idaho Capital Sun that quagga mussels pose serious challenges to Idaho.

In an email, he said the mussels have the potential to significantly impact native species, ecosystems, hydropower infrastructure, municipal and agricultural water use and recreation.

“Left unchecked, quagga mussels can cover the surfaces of dams, canals, and waterways,” he said. “They can plug pipes. They are filter feeders that outcompete all other species for nutrients, and have substantially changed ecosystems.”

Knight said this is the first finding of quagga mussels in Idaho and the Columbia River Basin, but that the department already had plans in place in preparation for this event.

“Our prevention program was one of the first to deploy watercraft inspection stations on primary routes of travel, and we have inspected over one million (watercraft) since the program started,” he said. “In addition, we take 1,500 water samples each year in the search of mussels in water bodies in every corner of the state.”

Knight said the department is working hard to implement its rapid response plan for the first time.

“First, we are working to contain the spread of the species by asking the public to stay away from the affected area so as to avoid moving water or invasive species from one water body to another,” he said. “Second, we are working to better define the current infestation, and we are sampling to ensure that we find any other infestations in the area. Finally, we are working on a treatment plan to eradicate the infestation as we know it.”

Knight said the department has reviewed several treatment options, and it is finalizing plans to apply a pesticide to control the invasive species.

To stay up to date on the latest information, visit the department’s quagga mussel response page on its website.