Idaho has had no new detection of an invasive mussel. How long until an infestation?

A little mussel not much bigger than a nickel that could wreak havoc on Idaho’s waterways has been on the minds of state officials for years. Last fall, they were confronted with the nightmare of a species for the first time.

In September 2023, the Idaho State Department of Agriculture reported the first detection in Idaho of quagga mussels, an invasive species, in the Snake River in Twin Falls. If the species isn’t eliminated, it can affect agriculture, power generation and wildlife, clogging up irrigation systems and even hydroelectric plants. But Idaho officials remain optimistic that the state can prevent a full infestation.

After the first and so far only detection in Idaho, the state implemented its rapid response plan, a strategy developed to eradicate the mussel, and spent $3 million to administer a copper-based chemical treatment in October to kill the species, Nic Zurfluh, invasive species bureau chief for the Idaho State Department of Agriculture, told the Idaho Statesman.

While no mussels have been found since the treatment, it could be five years of no detection before the state is classified as quagga-free, Zurfluh said.

Idaho started monitoring water and boats for the mussels in 2009 after they were introduced to the Colorado River basin, a close neighbor to the Columbia River basin, Zurfluh said.

A 2020 U.S. Geological Survey found that in Lake Mead, Nevada, the mussel, which was introduced in 2007, has changed the lake’s food web and put an endangered species, the Razorback Sucker, at risk. While in the Great Lakes, where quagga mussels have been for decades, it costs over $500 million annually to manage the mussels, according to the U.S. Department of Agriculture.

“The Columbia basin is essentially the last major watershed in North America, or at least the continental U.S., that does not have quagga mussels,” Zurfluh said.

Switching from prevention to mitigation of the species is never the outcome the state wants, and it would take “time and resources and money,” Zurfluh added.

A tiny mussel with big, expensive impacts

If the mussel were to infest Idaho’s waterways fully, it could have a huge impact on water usage and cost the state up to $100 million yearly in maintenance and mitigation strategies, Zurfluh said. Quagga mussels can attach to almost anything and quickly clog up irrigation and municipal water systems, as well as hydroelectric power plants.

“That’s why we’re concerned so much is because Idaho, especially Southern Idaho, relies heavily on hydropower for an energy source as well as surface water irrigation,” Zurfluh said.

Mussels jamming irrigation pipes could affect the price of agricultural goods by reducing water flow to crops, resulting in lower yields and causing expensive pipe maintenance, Zurfluh explained. In Southern California, Coachella Valley Water District charges farmers an irrigation water surcharge of up to $5.75 per acre-foot to help pay mussel-related maintenance costs.

As for hydropower, it accounts for 43% of the total electricity generation in Idaho, according to the U.S. Department of Energy. Quagga mussels, especially in their microscopic early stages of life, can get into hydropower infrastructure and choke water flow, reducing power generation, said Michael Stephenson, a biologist at Idaho Power.

In a 2010 report, the Independent Economic Analysis Board, an advisory group, estimated that a quagga mussel outbreak in the Snake River could cost up to $30 million a year in hydropower maintenance.

And then there’s the impact an infestation would have on wildlife. Quagga mussels are water-filtering powerhouses that take out essential nutrients needed by other wildlife. The cleaner water they produce would allow sunlight to penetrate deeper, causing plant life and harmful algae to flourish, which would alter the ecosystem and could kill Idaho’s natural aquatic species, Stephenson told the Statesman.

If an infestation were to happen, you might be able to see the bottom of the Snake River in areas that are 60 feet deep, Stephenson said.

While Stephenson was “thrilled” with the state’s quick response last year and is hopeful the treatment worked 100%, he cautioned that a new introduction could happen at any time.

“Now we know quagga mussels can survive in the Snake River,” Stephenson said. “There’s still potential for next week’s new introduction.”

Idaho residents can help

Zurfluh thinks the state’s preventive measures could keep Idaho from ever having a full-blown infestation, but he recognizes the luck that was involved with the detection area last fall. Low water flow and few species of concern in the area permitted the copper-based treatment, which is toxic to species other than quagga mussels. If the mussel were to be found in a different spot, that same treatment might not be an option, he explained.

Idaho continues to monitor waterways and boats entering the state for quagga mussels, and takes measures to “clean, drain and dry” watercraft to keep mussels from being introduced.

“If we didn’t have watercraft inspection stations, we would have had quaggas by now,” Zurfluh said.

Zurfluh urges any boat owner to be diligent in decontamination but thinks every Idaho resident has a part to play. If a shore starts to look different or have shells that recreationists haven’t seen before, they should call the Idaho Invasive Species Hotline.

“That can be really powerful information,” he said.

For Idaho residents, preventing an infestation could mean lower power bills, cheaper food and water, and “walking on a beach with no shells versus a beach covered in sharp shells,” Zurfluh said.