Environmental advocates are threatening to sue the U.S. Fish and Wildlife Service over delays in deciding whether the western ridged mussel should receive protection under the Endangered Species Act.
The freshwater species, found in rivers across parts of the Pacific Northwest and West, helps filter pollutants from waterways. Advocates say its decline could signal broader problems for river ecosystems.
Though easy to overlook, the western ridged mussel plays an important role in keeping rivers clean.
The mussels sit in riverbeds and filter water, removing particulate matter, bacteria such as E. coli and other pollutants. Meg Townsend, a freshwater attorney with the Center for Biological Diversity, said one mussel bed can filter about 4.5 pounds of particulate matter from a river each year.
“They’re pretty much the unsung heroes of clean water,” Townsend said. “While they may be small and look like rocks and be half submerged in riverbeds, their impact is just absolutely huge.”
Townsend said mussels are an important indicator of ecosystem health. When they disappear, she said, rivers lose part of their natural ability to stay clean, affecting the entire ecosystem.
Western ridged mussels once ranged from San Diego County into Canada, including parts of Idaho and Nevada, Townsend said. But Townsend said their range has shrunk by 43%, and they have disappeared entirely from the southern part of their California range.
Recent die-offs in Oregon and Washington are especially concerning, Townsend said. In some cases, thousands of mussels can die in a single summer.
Advocates push federal protections for western ridged mussel
The species faces several threats, including dams, pollution and runoff from agriculture and urban areas.
Dams can fragment fish populations, alter water temperature and disrupt sediment flow, all of which can damage mussel habitat. That is especially problematic because mussels depend on healthy fish populations to reproduce.
Townsend said the Center for Biological Diversity petitioned in 2020 to have the western ridged mussel listed under the Endangered Species Act. The Fish and Wildlife Service found the petition presented enough scientific information to warrant a full review, she said, but missed its August 2021 deadline to make a required decision.
Now, the group has issued a 60-day notice of intent to sue the agency.
Townsend said the legal action is intended to force the agency to decide whether the species should be listed as threatened or endangered.
Guest
- Meg Townsend, freshwater attorney, Center for Biological Diversity
