Invasive Mussels Threaten Western Waterways
Invasive aquatic species like quagga and zebra mussels are wreaking havoc across Western U.S. waterways, with costly implications for ecosystems, infrastructure, and state budgets. These tiny but destructive mollusks—originally from Central Europe—have steadily spread westward since their first U.S. appearance in the late 1980s. Today, they represent one of the most pressing environmental threats to freshwater systems in states like Nevada and Idaho, where officials urgently implement large-scale prevention and eradication efforts.
The Expanding Mussel Menace
Introducing quagga and zebra mussels to North America marked a turning point in aquatic invasive species management. Brought over inadvertently through ballast water in transoceanic ships, these mussels quickly took hold in the Great Lakes and spread across major inland waterways.
Unlike many regions where mussels create ecological nuisances, Western states rely heavily on rivers and lakes for irrigation, hydropower, recreation, and drinking water. Mussels clog water intake pipes, coat infrastructure, outcompete native species, and can even alter entire ecosystems. According to recent estimates, the U.S. has spent over $6 billion since 1988 on prevention, control, and mitigation efforts related to invasive mussels.
Nevada's Growing Concern: Lake Tahoe at Risk
In Nevada, the Department of Wildlife has sounded the alarm about the threat of mussels entering pristine lakes like Lake Tahoe. The potential for damage is massive—should zebra or quagga mussels gain a foothold, annual financial losses could exceed $20 million, officials warn. This figure includes the costs of removing mussels from water infrastructure, lost tourism revenue, and ecological restoration.
Adding to the concern is the emergence of a third invasive species: the golden mussel, first discovered in North America in late 2024 within the Sacramento River Drainage. Wildlife authorities are watching closely to prevent a new wave of infestation due to its proximity to northern Nevada and its destructive characteristics to quagga and zebra mussels.
Nevada's strategy hinges on robust prevention programs—especially public education and strict inspection protocols for boats and watercraft entering state waters. The Nevada Department of Wildlife's invasive species division continues to raise awareness and partner with other agencies to build a defense system for Lake Tahoe and other high-risk bodies of water.
Idaho's Massive Elimination Effort in the Snake River
While Nevada is trying to prevent an invasion, Idaho is in the midst of a full-scale battle to eradicate quagga mussels from the middle Snake River following a shocking discovery in September 2023 near Twin Falls. This marked the first time the invasive species had reached the Columbia River Basin, a vital watershed serving multiple Western states.
The Idaho State Department of Agriculture (ISDA) responded swiftly, launching what Director Chanel Tewalt has called the most considerable mussel elimination effort ever attempted in the U.S. At the heart of the campaign is the use of Natrix, a copper-based pesticide approved by the Environmental Protection Agency to target aquatic invasive species. Despite the significant ecological risks—including the unfortunate loss of thousands of fish during treatment—officials argue the alternative of doing nothing would be far worse.
"We knocked back the population, but finding any mussels is unacceptable," Tewalt told legislators during a February 2025 update. "They can reproduce between 2,000 to a million eggs per year."
High Costs, High Stakes
Idaho's efforts have not come cheap. The state allocated $6.6 million in its 2025 budget for invasive species control, heavily emphasizing the Twin Falls region. This follows previous expenditures of $1.5 million in 2023 and $2.1 million in 2024 on Natrix treatments, which increased in scope after early application results showed promise.
Despite the environmental costs, such as the death of 48 white sturgeon—some up to eight feet long and 35 years old—state leaders maintain that eradication is the only option. As Director Tewalt explained, "As heartbreaking as it is… doing nothing is worse."
Idaho's invasive species program, created under the 2008 Invasive Species Act, includes mandatory boat check stations, outreach campaigns, and ongoing scientific monitoring. State officials stress the importance of watercraft inspections, especially for out-of-state visitors whose boats may harbor hidden mussel larvae known as veligers—microscopic organisms invisible to the naked eye.
Out-of-State Boat Traffic a Key Risk Factor
One of the most serious threats to Idaho's ongoing progress is the continuous inflow of boats from other states. According to Tewalt, many visitors from drought-prone areas like Arizona and Colorado may not fully understand Idaho's water conservation priorities. She emphasized the need for better education and stricter enforcement at state borders to prevent accidental contamination.
"Idaho law says you will not haul a boat with ballast water in it," Tewalt explained. "You will not launch on Idaho waters if you are an out-of-state boater without having an inspection."
She compared the situation to livestock transport, where Idaho ranchers often encounter strict rules when entering states like California. "We need that same scaffolding," she said, suggesting boaters adopt a similar awareness and compliance mindset.
Mixed Progress: Hope on the Horizon?
Despite the seriousness of the situation, there are signs of hope. Nic Zurfluh, bureau chief of ISDA's invasive species program, noted that while larvae (veligers) have been found in specific stretches of the Snake River, there have been no confirmed sightings of adult mussels in all of 2024. This suggests that eradication efforts may be succeeding—though vigilance remains crucial.
"We've seen progress, but we're not out of the woods yet," Zurfluh said. "Monitoring the river and reinforcing partnerships with power companies, land management agencies, and private labs remain key."
The state has also relied on the expertise of local hydrologists, Idaho Power, and major private stakeholders like the Simplot Company to manage treatments and gather data.
A Regional Problem That Demands National Attention
While Idaho and Nevada bear the brunt of mussel-related battles, the broader issue affects much of the American West. As water becomes an increasingly scarce and valuable resource, any threat to delivery systems—especially those tied to agriculture, energy, and recreation—must be urgently treated.
Moreover, the long-term cost of invasive mussels is not just measured in dollars. The ecological damage they cause, from smothering native species to altering water chemistry, may take decades to reverse—if at all. Once fully established in a water system, quagga, and zebra mussels are virtually impossible to eliminate without resorting to drastic measures like those now underway in Idaho.
Final Thoughts: Prevention Over Cure — and a Glimpse at Innovative Solutions
The stories unfolding in Nevada and Idaho underscore a powerful lesson: prevention is always more cost-effective and environmentally sustainable than large-scale eradication. Once mussels take hold, even aggressive chemical treatments like copper-based Natrix can have unintended consequences, such as fish die-offs and ecosystem disruption. That's why forward-thinking prevention strategies—such as mandatory boat inspections, strict regulations on ballast water, and robust public education—remain the first line of defense.
However, as infestations continue to spread, there's increasing interest in biological control methods that can reduce the environmental footprint of eradication efforts. One promising solution is Zequanox, a naturally derived biopesticide developed by the Invasive Species Corporation. Unlike copper-based chemicals, Zequanox is made from a dead strain of the bacterium Pseudomonas fluorescens and selectively targets zebra and quagga mussels without harming native fish, plants, or other aquatic organisms.
Zequanox works by being ingested by the mussels, ultimately causing death by disrupting their digestive system. It's been approved by the U.S. Environmental Protection Agency and has already shown success in localized treatments, especially in enclosed or controlled aquatic environments. As states explore longer-term, less damaging eradication tools, Zequanox could represent a turning point in addressing established mussel populations while minimizing collateral damage to native ecosystems.
Ultimately, prevention must remain a top priority—but having more innovative, safer tools like Zequanox in the toolkit gives agencies a much-needed alternative when prevention fails. By combining proactive policies with innovative treatments, Western states may be able to turn the tide in their ongoing battle against invasive mussels.
