The presence of invasive quagga mussels was confirmed in the Snake River near Twin Falls in the fall of 2023. 

September 24, 2024, ISDA confirmed the detection of quagga mussels in the Twin Falls area of the Snake River. Current monitoring results show a decrease of quagga mussel presence in the affected stretch of river since the pre-treatment surveys in 2023.  

The introduction of quagga mussels poses a major threat to Idaho. This invasive species can quickly spread and clog pipes that deliver water for drinking, energy, agriculture, recreation, and a variety of other uses. Quagga mussels have the potential to destroy our waters and cost Idaho hundreds of millions of dollars in actual and indirect costs.  

In 2023 ISDA implemented a treatment of the river with a chelated copper product. It was the first treatment of this type and scale ever attempted in North America. Sampling results indicate the chelated copper treatment was effective in reducing the mussel population.   

Since the detection in 2023, ISDA has doubled quagga mussel sampling, ran more inspections stations, increased statewide communications, added manpower, and collaborated with more partners. The ISDA Invasive Species Program has more information and resources than ever before to combat this invasive species. 

ISDA is currently implementing a public access closure and mandatory inspection and decontamination of watercraft in certain stretches of the Mid-Snake River. These efforts are a part of a rapid response plan to minimize the potential movement of invasive quagga mussels. 

Please visit our Invasive Species of Idaho website for more information: IDAHO.GOV/QUAGGA