Boise, Idaho — The Idaho State Department of Agriculture announced today a 51% reduction in the quagga mussel impacted area of the Snake River near Twin Falls. Extensive sampling shows the area impacted by quagga mussels is approximately 3.5 river miles, which is down from an impact area of 7.2 miles in 2024. The results show significant progress and demonstrate the effectiveness of ISDA’s ongoing treatment strategy.  

No quagga mussels have been detected upriver or downriver of the 2024 treatment zone. Of concern to irrigators in the Magic Valley, no mussels have been detected in nearby reservoirs.   

“Quagga mussels pose a serious threat to Idaho’s water infrastructure, ecosystems and economy,” said ISDA Director Chanel Tewalt. “Full eradication remains the goal, but even reaching a level of containment is uncommon in other U.S. systems. ISDA’s treatments are critical to prevent widespread impacts to agriculture, power generation and Idaho’s aquatic environments.”   

This year, ISDA has conducted over 450 samples in the infested area of the Snake River and more than 4,514 statewide.   

Effectively treating the Snake River presents unique challenges due to the river’s complexity. Freshwater inputs in 2023 and 2024, along with varying river depths and flow rates have influenced how treatments dissipate to the target species. With an inventory of freshwater inputs and a detailed understanding of river dynamics, ISDA is developing a targeted treatment plan for 2025.   

“The City of Twin Falls, Jerome County and Twin Falls County are proud to stand alongside the Idaho State Department of Agriculture in this critical fight against quagga mussels,” Twin Falls Mayor Ruth Pierce, Jerome County Chairman Ben Crouch and Twin Falls County Chairman Don Hall said in a joint statement. “Thanks to ISDA’s swift action and expertise, the infestation has been contained to a small stretch of the Snake River, and we are encouraged by this progress. Protecting our waterways from quagga mussels is essential to our farms, residents and the entire Magic Valley community, and this partnership is key to safeguarding the future of our region.” 

ISDA is committed to a strategic, science-driven response to fully eradicate this invasive species and protect the state’s waterways. Similar to 2023 and 2024, ISDA will make its full treatment plan available to the public. The plan will be shaped by extensive ongoing sampling and careful evaluation of the Snake River’s complex flow patterns and site-specific dynamics. 

For updates and closure information, visit idaho.gov/quagga.  

Stakeholder Responses to the 2025 Detections: 

Idaho Power supports state efforts to eradicate invasive quagga mussels that have been found in the Snake River. Quagga mussels can cause significant damage to hydroelectric power plants by clogging water intakes and piping, which can reduce energy production, leading to increased costs to customers. Quaggas also pose a threat to irrigation and recreation facilities and the river’s ecosystem. - Ryan Adelman, Idaho Power Vice President of Power Supply  

Idaho’s water is the backbone of our communities, economies, and agricultural success. Quagga mussels threaten that lifeline by clogging critical infrastructure, including disrupting irrigation systems that farmers and water users depend on every day. The recent findings highlight the urgent need for continued, aggressive response. We have learned that this is not going to be a "one-and-done" effort - we must remain vigilant.  We fully support ISDA’s ongoing efforts. Their swift and science-based actions will prevent this threat from spreading further. Protecting our water now is essential to ensuring its availability for future generations. - Paul Arrington, Idaho Water Users Association   

A 50% reduction in the quagga mussel impact area is a significant milestone and shows real progress in this fight. At the same time, we know how devastating quagga mussels can be for Idaho agriculture if they are not eradicated. We call on ISDA to do everything necessary to finish the job and reach eradication. - Bryan Searle, Idaho Farm Bureau Federation  

The Twin Falls Canal Company (TFCC) fully supports the ISDA in its efforts to eradicate quagga mussels in Southern Idaho. Agriculture is the backbone of Idaho’s economy, and water is essential to its success. The presence of this invasive species threatens TFCC’s ability to deliver water to our shareholders. ISDA has a strong track record of working collaboratively with TFCC and other stakeholders to quickly deploy plans and equipment that protect our farms, families, and communities. TFCC remains confident in ISDA’s ability to keep Idaho’s water systems free from this harmful species. - Jason Brown, Twin Falls Canal Company  

Quagga mussels could cripple the canal systems and on-farm irrigation systems that deliver water to crops across Southern Idaho, and be devastating for irrigators. Thanks to ISDA’s treatments in 2023 and 2024, producers have been spared another year of costly disruptions and uncertainty. We call on ISDA to continue taking aggressive action, because protecting agriculture depends on keeping these mussels out of our irrigation systems.  North Side Canal Company fully supports and applauds their continued response and efforts to control this invasive species. - Alan Hansten, North Side Canal Company  

These detections are a reminder of how persistent and damaging quagga mussels can be, and why we must stay diligent. It’s encouraging to see that the infestation appears to be shrinking, which indicates the response is working. The Nature Conservancy supports ISDA’s continued efforts and urges the agency to take responsible, science-based action to protect Idaho’s rivers and the ecosystems that depend on them. - Bas Hargrove, The Nature Conservancy in Idaho

Quagga mussels pose a serious threat to Idaho’s commerce, agriculture, and energy infrastructure. Thanks to the leadership of ISDA and the coordinated efforts of state partners, Idaho has made meaningful progress in controlling the invasive mussels first detected in 2023. Now is the time to build on that momentum and advance another round of treatment. IACI and our members fully support ISDA’s continued work to eradicate quagga mussels from the Snake River and protect Idaho’s economy and natural resources. - Alex LaBeau, Idaho Association of Commerce & Industry  

Since quagga mussels were first detected in the Snake River in 2023, the Northwest Power and Conservation Council has supported Idaho’s eradication efforts.  These mussels are one of the gravest threats to the Northwest’s hydropower system, which supports our regional economy.  They’re a threat to fish and wildlife populations and water supplies in the Columbia Basin. Over the last decade, the Council has also strongly supported regionally coordinated efforts to proactively keep mussels out of the Basin, and to obtain federal funding necessary to bolster Idaho’s efforts. The Council urges the State of Idaho to continue doing everything possible to eradicate quagga mussels. - Ed Schriever and Jeff Allen, Northwest Power and Conservation Council  

Idaho irrigators know what is at stake with a potential spread of quagga mussels. All along the Eastern Snake Plain farmers are concerned about this invasive pest spreading to canals, pumps, and more. Thanks to the hard work of ISDA, we are seeing progress towards eradicating quagga mussels. Now is not the time to let up and I applaud Director Tewalt and her decision to continue treatment on the remaining mussels. Idaho groundwater users stand with the State of Idaho in this effort. - Stephanie Mickelsen, Idaho Groundwater Appropriators  

Reliable access to water is essential to Idaho’s dairy industry, from growing feed to supporting daily operations. Quagga mussels put that reliability at risk. The Idaho Dairymen’s Association commends ISDA for saving Idaho farmers another year from direct costs associated with these impacts and calls on ISDA to take action on the latest findings and proceed with additional treatment to protect our water infrastructure and the industries that depend on it.  - Rick Nearabout, Idaho Dairymen’s Association  

We call on ISDA to act decisively based on the latest findings to eradicate quagga mussels. Idaho’s rivers and lakes support world-class fishing, hunting access, and year-round outdoor recreation that sportsmen and communities across the state depend on. Fighting this threat to our waterbodies now preserves the traditions that define our state. - Benn Brocksom, Idaho Sportsman Access  

The Idaho potato industry needs ISDA to take necessary action on the river to safeguard the future of our industry. Idaho potatoes depend on reliable irrigation systems, and quagga mussels put that lifeline at risk. An established quagga mussel population in Idaho would mean that the backbone of our state, our farmers, would face significant long-term costs for irrigation due to clogged canals and delivery systems.  - Daren Bitter, Idaho Potato Commission   

Quagga mussels pose a serious threat to Idaho’s rivers, native species, and the fish and wildlife habitat that so many Idahoans cherish. Working to ensure the long-term health of our waterways is essential not only for recreation but for conserving the ecosystems that define our state. The Idaho Wildlife Federation strongly encourages ISDA to continue taking the appropriate actions to stop the spread of quagga mussels and safeguard the natural resources that are at the heart of Idaho’s outdoor heritage. — Nick Fasciano, Idaho Wildlife Federation  

Over 400 sugarbeet growers in Idaho rely on the Snake River for irrigation, and quagga mussels put that lifeline at risk. Water is the lifeblood of our agricultural economy, and we must take necessary actions to protect it. We are encouraged by the progress made so far, but this work must continue. We strongly support ISDA moving forward with another round of treatment to protect our growers and the communities they sustain. - Samantha Parrott, Snake River Sugarbeet Growers Association  

ISDA must move forward with their strategic treatment to protect Idaho’s water systems. Our growers rely on dependable irrigation to produce high-quality grain, and our river systems are critical for transporting wheat to market. Any threat to that infrastructure puts our farms and supply chains at risk. - Amaya Aguirre-Landa, Idaho Grain Producers Association   

  

Media Contact 

Sydney Kennedy 

Public Information Officer 

(208) 986-1566 

media@isda.idaho.gov