Idaho officials describe quagga mussel eradication push and technical hurdles

Chanel Tewalt, Director of the Idaho State Department of Agriculture, told the Senate Resources & Environment Committee that Idaho’s task force treated the Snake River in 2025 and continues to pursue eradication of quagga mussels.

“One mussel produced 300,000 up to 1,000,000 veligers per year,” Tewalt said, describing why even a single adult can rapidly repopulate a water body. She said Idaho treated upriver of Twin Falls as far as boats could operate, and that the gold line on her slide indicated where larval mussels were found while a dotted line marked river miles. Senators asked technical questions about how treatments enter the water column, why reaching 30-foot depths is difficult, and why smooth-flowing stretches without natural mixing are harder to treat.

Tewalt described the treatment strategy and its limits, saying staff looked for products that remain bioavailable long enough to halt mussel respiration and that larvae—lacking shells—are killed at much lower concentrations. She said other states have observed Idaho’s methods but often lacked political support to accept the expected side effects of treatment in their jurisdictions. Committee members asked about ecological impacts; Tewalt said heavy mussel concentrations in the Great Lakes have been measured in feet of shell, contributing to algae blooms and bird die-offs.

The committee did not take formal action. Tewalt offered to follow up on questions about possible economic uses for mussel shells and whether mussel populations ever ‘burn out’ from overpopulation.