In summer of 2024, HRWC staff, interns, and volunteers embarked on an intensive mussel survey in the Huron River, declared by program staff as: The Great 2024 Huron River Mussel Hunt. The mussel survey was part of the project to remove Peninsular Paper Dam in Ypsilanti. “Pen Dam” is a high-hazard dam recently downgraded to “poor” condition by the State of Michigan.

 Check out this fun video about our 2024 Search for Mussels in the Huron River, Ypsilanti
an striped orange mussel sits in the palm of a gloved hand.
One of the state threatened species found during HRWC’s mussel survey was the Wavy-rayed lampmussel.
credit: HRWC

A key element of dam removal is understanding the impact of the removal on aquatic life around the dam. The Huron River has good habitat for freshwater mussels, and the stretch of river around the dam could be particularly high-quality habitat for mussels and other aquatic organisms once restored. However, when dams are removed the sediment released can temporarily harm downstream habitat. Many animals like fish can move freely to avoid the impacts of dam removal, but slowmoving mussels don’t fare as well. Engineers involved with the Pen Dam removal do not anticipate much sediment being released, but we are taking extra precautions because of the fragility of freshwater mussel population

Why do mussels matter?

Freshwater mussels are important animals in a river ecosystem because they filter bacteria, provide habitat and food for other animals, and serve as water quality indicators. Unfortunately,  variety of factors have driven the decline of musse worldwide. In Michigan, half of the state’s 43 mussel species are currently threatened, endangered, or species of special concern. Mussel populations have declined due to water pollution, invasive species like zebra mussels, and the presence of dams. Since mussels cannot move well on their own, they rely on fish to carry their larvae upstream. Dams like Pen Dam inhibit fish passage and  therefore limit the resilience of the mussel species that rely on those fish for reproduction.

Digging for mussels

Using a mask and snorkel is the best way to find mussels under the water.
credit: HRWC

HRWC staff worked alongside mussel biologists Renee Mulcrone and Amani Tolin from PEA Group to lead the mussel survey. This survey was the most intensive single biological monitoring project HRWC has ever led, and the results were great! Throughout June and July, 50 volunteers and 24 HRWC summer interns surveyed 90 transects in the Huron River below Pen Dam. Volunteers included biologists from the Michigan Department of Natural  Resources, the U.S. Fish and Wildlife Service, engineering consulting firms, and the Michigan Department of Transportation.

Many species of mussels were found, notably the Wavy-rayed lampmussel and Black Sandshell, which are both state threatened species. Because several sensitive species were found during the survey, mussels around the dam will be relocated before the dam comes out.

A unique opportunity

Volunteer hands mussel to mussel biologist Amani Tolin so he can identify and measure it.
credit: HRWC

Strict permitting processes restrict who is allowed to work with freshwater mussels in the State of Michigan. As such, it is difficult for people interested in this field of work to get hands-on experience with mussels. Many mussel biologists have noted their struggle to recruit the next generation of mussel experts. By connecting expert practitioners with young professionals through projects like the Pen Dam mussel survey, HRWC is in a unique position to address this problem. Building on the work Amani Tolin started while pursing his master’s degree and interning with HRWC in 2022 and 2023, HRWC’s mussel work has given dozens of young professionals the rare opportunity to participate in freshwater mussel science. Connecting our field internship with our mussel work offered HRWC’s summer interns unique resumebuilding experience and perhaps has inspired future mussel biologists!

For all those that got to dive under the surface, the Great 2024 Huron River Mussel Hunt was a truly singular experience.

—Melina Pakey-Rodriguez

See our earlier blog by a similar name, The Great 2024 Mussel Hunt!, to read more about the mussel surveying process. Or check out our 3-minute video about the mussel project.

See the Fall 2023 Huron River Report for more information on the Peninsular Paper Dam removal.

This blog post is also published in the Huron River Report, Fall 2024.