by Mia Maldonado, Oregon Capital Chronicle
June 24, 2026
Survey crews from Portland State University discovered a dead, highly invasive mussel earlier this month along the shoreline at Prineville Reservoir.
The singular adult quagga mussel was located 1 meter above the waterline on June 6 when crews from the university’s Center for Lakes and Reservoirs collected it and contacted the Oregon Department of Fish and Wildlife, the Oregon State Marine Board and the Oregon Invasive Species Council.
The discovery marks the first time the highly invasive mussel has been found near an Oregon waterbody.
Test results from water samples and environmental DNA tests by the university showed no sign of further invasive mussels in the reservoir, but the state is taking this discovery extremely seriously, said Keith DeHart, the fish and wildlife department’s aquatic invasive species coordinator.
“We are coordinating closely with our state, federal, tribal and local partners and preparing to move quickly based on the evidence we find,” DeHart said in a statement. “Our top priority is protecting Oregon’s waters while making sure every action we take is grounded in the best available information.”
Quagga mussels pose a serious environmental and economic threat to freshwater waterways, especially in the Pacific Northwest. The freshwater mollusks were first introduced into the United States in the 1980s and have the potential to clog irrigation and hydroelectric infrastructure, outcompete native species and disrupt recreation.
In neighboring Idaho, state officials since 2023 have spent millions of dollars trying to eradicate quagga mussels from parts of the Snake River, the state’s longest river heavily relied on by farmers to irrigate the state’s most important crops such as potatoes and wheat. The mussels were discovered near Twin Falls, located 180 miles east of the Oregon border. State officials used aquatic pesticides to combat the mussels, killing millions of fish in the process, including decades-old sturgeon.
Monitoring teams will continue routine sampling efforts to ensure early detection and subsequent rapid response if quagga mussels are present in the reservoir, according to the fish and wildlife department.
Recreational boats traveling from out-of-state waterways are a major source of invasive mussel spread. Oregon law requires any vehicle transporting watercraft to stop at all open watercraft inspection stations.
To report an invasive freshwater mussel on watercraft, call the Oregon Invasive Species hotline at 1-866-INVADER or visit the hotline website.
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