Quagga battle
ISDA confirmed a detection of quagga mussels in the infested area of the Snake River. Sampling has shown a 51% reduction in the quagga mussel impacted area of the Snake River near Twin Falls. 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.
ISDA is committed to a strategic, science-driven response to fully eradicate this invasive species and protect the state’s waterways. The 2025 treatment plan is shaped by extensive ongoing sampling and careful evaluation of the Snake River’s complex flow patterns and site-specific dynamics.
The 2025 treatment will utilize the chelated copper product, Natrix, and is set to begin September 30 and conclusion is estimated by October 10. View the full treatment plan below.
Why is the treatment needed?
The Snake River is complex, shifting flows, deep holes, spring inputs and natural refuge areas create challenging conditions that influence treatments. Like any eradication plan in agriculture, these plans take time and strategic effort. While this eradication strategy has shown strong results, it is not a one-time effort but an on-going strategic fight to protect Idaho’s waterways. With more sampling data, a deeper understanding of river dynamics, and a more contained area of the river, ISDA is prepared to effectively treat the quagga mussel population.
What is the treatment?
The treatment will utilize the chelated copper product, Natrix, and is set to begin September 30 and conclusion is estimated by October 10.
Natrix was used in the Snake River quagga mussel treatment in 2023 and 2024 which significantly reduced the quagga mussel population and resulted in a 51% reduction in the quagga mussel impacted area from 2024.
Natrix is a copper-based product that is labeled and approved by EPA for this type of aquatic applications. The product has been used in other states for mussel, fish, algae, and plant control.
The application rate of Natrix will kill mussels but is below the drinking water standard for humans.
The product dissipates downstream and is expected to be gone within three days after the final application.
River copper levels are expected to return to normal near the Highway 46 bridge.
ISDA and the Idaho Department of Environmental Quality will routinely monitor the river to evaluate treatment effectiveness and copper dissipation. ISDA has mitigation efforts ready to deploy if additional copper is detected downstream.
