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Agriculture & Water | Legislative Council on River Governance (LCRG)

Quagga Mussels in the Snake River: Update

By Jacqueline Tinetti

The Idaho State Department of Agriculture (ISDA) recently announced a targeted quagga mussel treatment to eradicate the small population of the invasive species in the Snake River.  On October 8, ISDA and contractors launched a 10-day comprehensive treatment from downriver of Hansen Bridge to Centennial Waterfront Park.

The treatment product is the same product used to treat the Snake River in 2023, a copper-based product called Natrix. The 2023 Natrix treatment significantly reduced the quagga mussel population in the Snake River. 

The current treatment is the first of the multi-faceted treatment plan. ISDA is planning a second treatment in November to target quagga mussels in still water and deep pool sections of the river.

Out of an abundance of caution to minimize exposure, ISDA advises the public to stay out of the dissipation area, from Hansen Bridge to Kanaka Rapid. 

The treatment is expected to dissipate to normal river copper levels eighteen miles downriver at Kanaka Rapid. ISDA and the Idaho Department of Environmental Quality will monitor the river from downriver of Hansen Bridge to Kanaka Rapid to evaluate treatment effectiveness and copper dissipation. 

Quagga mussels spread rapidly and clog pipes that deliver water for drinking, energy, agriculture, recreation, and a variety of other uses. Established quagga mussel infestations have major impacts on fish populations, wildlife habitat and damage infrastructure so severely costing hundreds of millions of dollars in actual and indirect costs.

Quagga mussels were first identified in the Snake River near Twin Falls in September 2023. The ISDA implemented a treatment with a chelated copper product, the first treatment of this type and scale ever attempted in North America. 

Eradicating and mitigating the impacts of aquatic invasive species such as quagga mussels is an important issue to state policymakers who represent communities along the Columbia and Snake river basins. These concerns were recently discussed at the CSG West Legislative Council on River Governance meeting in Richland, Washington. Moreover, this summer CSG West’s Executive Committee adopted a resolution calling for greater harmonization of state – provincial approaches to invasive species management.  A copy of the resolution can be viewed HERE