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Western Ridged Mussel

ESA Status: Under Review

The western ridged mussel is a freshwater mollusk native to western North America. The Xerces Society for Invertebrate Conservation’s Petition to List, completed in 2020, identified the mussel’s historic range in river basins throughout California, Idaho, Nevada, Oregon, Washington, and British Columba, Canada. The U.S. Fish and Wildlife Service (USFWS)’s 90-Day Finding, released in 2021, found the Petition presented substantial information indicating that further action may be warranted.

The 90-Day Finding highlighted potential threats to the western ridged mussel as habitat destruction, modification, and curtailment, poor water regime quantity and quality, invasive species, disease, and inadequate regulatory mechanisms. The USFWS’s findings now initiate a status review of the species to determine whether actions under the Endangered Species Act (ESA) are warranted.

Staff Contact:

Mike Edmondson

More Information:

Species Profile for Western Ridged Mussel – U.S. Fish & Wildlife Service

Mussels in a stream
Western Ridged Mussels
Idaho map with highlighted range along western side of state
Western Ridge Mussel range
Map Credit: Idaho Department of Fish and Game
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