ISDA Wraps Up Quagga Mussel Treatment For The Year

The Idaho State Department of Agriculture has completed its 2026 treatment of the Snake River for invasive quagga mussels.

The multi-phase treatment began August 27th and concluded September 16th, using three copper-based products. ISDA said sampling shows a 77% reduction in quagga mussel detections near Twin Falls.

What was this year's treatment?

The treatment utilized Natrix, Earthtec QZ and Cutrine Plus Granular.

Natrix has been used in the Snake River quagga mussel treatments in 2023, 2024, and 2025, which significantly reduced the quagga mussel population.
Earthtec QZ is another copper-based product that has a different formulation intended to address potential safe harbors in the infested area that may have quagga mussels.
Cutrine Plus Granular was deployed in mesh bags at targeted fissures harboring quagga mussels. The bags were deployed for 96 hours and were removed following the conclusion of the treatment.
Natrix, Earthtec QZ and Cutrine Plus Granular are copper-based products that are labeled and approved by EPA for this type of aquatic application. The products have been used in other states for mussel, fish, algae and plant control.
The application rate of the products was designed to kill mussels while remaining below the drinking water standard for humans.
Copper is naturally occurring in this system. The treatment products dissipate downstream and are expected to dissipate within days after the final application.
River copper levels are expected to return to normal within 25 miles, near the Highway 46 Bridge.
ISDA and the Idaho Department of Environmental Quality monitored the river to evaluate treatment effectiveness and copper dissipation. ISDA had mitigation efforts in place to deploy if additional copper was detected downstream.

Impact Of The Treatment:

Treatment application occurred across two individual target locations of the river in efforts to eradicate quagga mussels at all life stages.
The labels for the products used indicate no impact on any drinking water sources. The application rate of Natrix, Earthtec QZ and Cutrine Plus Granular at the immediate application site was lower than the drinking water standard. There were no public drinking water intakes near the treatment area of the Snake River.
The treatment caused minimal mortality in fish, aquatic plants and algae from Sage View downstream to Highway 46 Bridge.

ISDA added copper levels and treatment impacts continue to be closely monitored.

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