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Freshwater mussels are a frequently overlooked component of our aquatic environment, buried in the substrate of rivers, streams, ponds, and lakes.

Mussel Services

Because of the inconspicuous nature of mussels, many people are surprised to discover that there are many different species, and that North America has the greatest diversity of mussels in the world, with close to 300 species historically. Despite this diversity, freshwater mussels are one of the most imperiled groups of animals in the country. Thirty-eight species are presumed extinct, and approximately 70 percent of the remaining species in North America are in danger of extinction and are Federally or State listed.

Creeper Mussel SWCA With so many protected species, the presence of mussels within a project area often requires special permitting. Some of the types of projects that can impact rare mussels include:

  • bridge construction or repair (DOT, Railroad)
  • stream and river crossings (pipelines, sewer lines, water lines)
  • dredging
  • dock installations and repairs


If a project falls within an area of known occurrence, the project is reviewed by state or federal agencies to determine if there are potential impacts to rare mussels. If it appears likely that mussels will be impacted, the development/implementation of a Mussel Protection Plan (MPP) by a qualified mussel biologist may be required. In many cases, there are two components to an MPP: an initial survey to determine presence and distribution of rare species, and the translocation of rare mussels out of the work footprint.

Mussels Diving In 2016, SWCA biologists conducted 56 days of diving, primarily focused on rare freshwater mussels. Recent projects involved developing protection plans and carrying out surveys and translocation work at numerous sites, as well as research-based surveys for USFW. Examples of recent projects include:

  • the translocation of over 80 Yellow Lampmussels (Lampsilis cariosa) from a remediation site in the Connecticut River
  • translocation of four state-listed species from a bridge replacement project in Vermont, involving nearly 1,300 individual Pocketbook (Lampsilis ovata), Fluted Shell (Lasmigona costata), Giant Floater (Pyganodon grandis), and Cylindrical Papershell (Anodontoides ferussacianus)
  • surveying populations of the federally endangered Dwarf Wedgemussel (Alasmidonta heterodon) in Massachusetts and New Hampshire

Our dive season extended from May to December this year, but generally the most efficient time to survey for mussels is from early summer into mid-fall. Contact us to learn more about our mussel services.