State of Washington Interagency Zebra and Quagga Mussel Rapid Response Plan

Zebra Dreissena polymorpha and quagga Dreissena rostriformis bugensis mussels are freshwater mollusks native to Ukraine and Russia that have a long history of invasion and successful establishment outside their native habitat. Once they are established, they can cause catastrophic ecosystem impacts, outcompeting native mussels and other filter feeding invertebrates, removing habitat for invertebrates, and reducing water quality. They can also have direct economic and safety impacts, clogging water intake structures, fish screens, and boat engines; overtaking docks, buoys, boat hulls, anchors, and beaches; and contributing to disease outbreaks in species that consume them.

Zebra and quagga mussels were first discovered in the United States in the Great Lakes region in the 1980s, thought to have been transported in ballast waters of trans-oceanic ships. Since the late 2000s, they have been spreading throughout the western United States (Nevada, California, and Montana), with the most recent detection in the Snake River in Idaho. While a comprehensive eradication effort is underway in the Snake River, the presence of dreissenid mussels in the Columbia River Basin (CRB) has alarmed the region and led to the requirement to revise the Washington State Interagency Zebra and Quagga Mussel Rapid Response Plan (Plan).