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Invasive Quagga Mussels, and Why They're a Problem

Posted on October 5, 2023   |   Updated on September 30, 2025
Natalia Aldana

Natalia Aldana

A quagga mussel photographed in 2008.

Invasive quagga mussels were first found in the Great Lakes in 1989. (NOAA Great Lakes Environmental Research Laboratory/Wikimedia Commons)

The Idaho State Department of Agriculture is working to contain the latest threat from invasive quagga mussels that were detected in the Snake River near Centennial Waterfront Park by Twin Falls on Sept. 19. Lab results have confirmed the presence of its free-floating larvae.

Why is this a problem?

These mussels are here to destroy. Quagga mussels are one of the most aggressive invasive species in the U.S. for their ability to damage infrastructure and clog irrigation pipes, drinking water intakes, and dams. Their destruction would also be expensive — potentially costing the state $100 million in repairs. Quaggas reproduce at faster rates than native mussels, so they are very difficult to eliminate after they’ve set up shop.

Idaho has spent millions since 2009 to keep the invasive mussels out, and until now, the Columbia River Basin was the only major river system in the U.S. without the presence of quaggas or the similarly invasive zebra mussels.

What’s next?

Gov. Brad Little called their discovery a “potential crisis,” and the window to mitigate the spread is narrow.

ISDA is currently using a molluscicide, a chemical substance developed specifically for destroying mollusks. The product will be released in the Snake River and split up into two 96-hour periods to kill parts of the ecosystem in affected areas.

ISDA is asking the public to stay out of the water on either side of the Perrine Bridge and to call them to decontaminate your boat, kayak, paddleboard, or fishing equipment if it’s been in the Snake River within the past 30 days.

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