Focused Treatment Strategy Limits River Access
The Idaho State Department of Agriculture has launched its fourth annual effort to combat quagga mussels in the Snake River near Twin Falls, taking a more precise approach this year by concentrating copper treatment on two specific deep pools rather than treating an extended stretch of water.
The invasive mussel species was first discovered in the Snake River in 2023. Since then, the department has conducted annual treatment campaigns to control the population and prevent further spread of the organisms, which can damage irrigation infrastructure, hydroelectric facilities, and water intake systems throughout the region.
ISDA Director Chanel Tewalt explained the shift in strategy, saying the department plans to be “very specific” to targeted locations. Rather than applying treatment across a wider section of river, the 2026 effort focuses on the deep pool above Twin Falls Dam and the deep pool above Shoshone Falls.
Access Limitations During Treatment Period
The targeted treatment approach allows portions of the river to remain accessible to boaters and water recreationalists, though several launch points will face temporary closures. The Twin Falls boat ramp will remain closed through September 5, while the Shoshone Falls boat launch will be closed from September 6 through September 13.
The Centennial boat launch, which has remained closed since suffering structural damage in prior years, will stay accessible for kayaking and paddleboarding throughout the treatment window, providing a recreational option near Twin Falls during the campaign.
Idaho Department of Agriculture officials are discouraging swimming in treated areas during the operation. For boaters seeking alternatives during the closure periods, Shoshone Falls boat launch represents the closest public launch point to downtown Twin Falls when the primary ramp is unavailable.
Why the Targeted Approach
The shift to targeted treatment reflects lessons learned from three previous years of control efforts. By concentrating copper applications on the specific deep pools where quagga mussels are most likely to concentrate, the department aims to maximize treatment effectiveness while minimizing disruption to recreational use and maintaining water access for regional users who depend on the Snake River.
Deep pools provide ideal habitat for quagga mussels to establish colonies, making them the logical focus of copper treatment. The approach also reflects a more efficient use of treatment resources by addressing the areas of highest ecological and economic concern.
Broader Infrastructure Context
The quagga mussel control effort is part of a larger set of water management and infrastructure priorities in Twin Falls County. The region continues to address critical transportation projects, including ongoing work at the Jerome I-84 interchange and the new southbound bridge construction, which intersect with water management considerations.
The Snake River and its associated irrigation systems remain vital to the agricultural and economic foundation of the Magic Valley. Invasive species control and infrastructure maintenance are ongoing priorities for the region.
What Comes Next
The department’s fourth annual treatment campaign will conclude by mid-September once both targeted deep pools have been addressed. Boat launch closures are expected to lift according to the announced schedules, allowing full recreational access to return to the Snake River near Twin Falls.
Ongoing monitoring by the Idaho State Department of Agriculture will assess treatment effectiveness and inform planning for future control efforts. The department will likely continue annual treatments in subsequent years as part of a long-term invasive species management strategy for the region.
Residents and recreationalists should monitor official announcements from the Idaho State Department of Agriculture for any updates to closure dates or treatment timelines during the campaign period.