Assessing hatchery infrastructure for invasive Dreissenid mussel vulnerability in eastern Washington

Zebra (Dreissena polymorpha) and quagga (Dreissena rostriformis bugensis) mussels have caused the highest economic costs among all aquatic invasive species in the United States (Washington Department of Fish and Wildlife (WDFW) 2016). Officials estimate that if zebra and quagga mussels become established in Washington, removal and management costs could exceed \$100 million annually (WDFW 2024a). The Pacific Northwest’s first confirmed detection of quagga mussels occurred in September 2023, when quagga mussel larvae were identified in the Snake River near Twin Falls, Idaho, approximately 280 river kilometers upstream of the Washington border and 680 river kilometers upstream of the Snake-Columbia River confluence (Washington Invasive Species Council 2023). Subsequently, quagga mussel larvae have been detected in Idaho waters at Shoshone Falls Pool, Pillar Falls, and Twin Falls Reservoir located upriver of the Twin Falls hydroelectric facility (Idaho State Department of Agriculture 2024). Additionally, zebra mussels were found in aquarium moss balls at pet stores in Washington in 2021 and 2024. However, neither zebra nor quagga mussels have been detected in Washington’s natural waterways (WDFW 2024b).