Extensive study finds dam removal heals Maple River, near Pellston

After an Emmet County dam was removed in 2019, researchers from the University of Michigan say the river it blocked was able to restore itself.

A recently published study from the school’s biological station in Pellston looked at chemical, physical and biological data collected over nearly a decade as the Lake Kathleen Dam was removed from the Maple River.

The dam was built in 1884 as part of a hydroelectric plant. In 2014, it nearly failed due to high water levels and was finally dismantled in 2019.

Researchers identically sampled the Maple River’s chemistry and ecology annually at five sites from 2012 to 2021. They found while water discharge increased seven-fold in the immediate aftermath, the river returned to its normal flow after about two years.

“The river recovered from that moving of sediment and heavy groundwork that was going on,” said research leader Paul Moore of Bowling Green State University. “And now going forward, it looks absolutely gorgeous, it's a beautiful connected stream now.”

After the dam was removed, the chemistry of the river was also altered. Students at the biological station noticed an increase of erosion due to more water flow as the lake disappeared, likely causing an increase in ammonia, phosphate and silica, and a drop in pH.

The study also paid attention to macroinvertebrates communities — tiny insects with huge roles in maintaining the ecosystem.

Species like crayfish or caddis flies increased dramatically in the upstream sites and water filterers like mussels or clams had a large increase at sites closest to the dam. Both are likely thanks to new algal growth in the streambed.

Moore said the smooth deconstruction of the Lake Kathleen Dam also helped maintain the ecosystems.

“If somebody stuck a knife in your leg, there'd be this big open gash. If it's not healed correctly, it's gonna take a long time to recover,” Moore said. “But this group went out with really heavy equipment, moving lots of concrete and lots of sand and lost material. They did it beautifully, like a doctor sewing you up so you recover a lot faster.”

The study comes as dam removal gains popularity around the state. Research points to most dams as being harmful to rivers by blocking migratory fish and warming the waters.

Multiple dam failures, like the ones that damaged communities in Midland and Gladwin Counties in 2020, have raised concerns for their age.

The state has a handful of other high-hazard dams, some of which are located in Northern Michigan. These include the Buttermilk Creek Detention Dam in Ottawa County, Cornwall Creek Dam in Cheboygan County, the Manistique Papers Dam in Schoolcraft County, and the Little Black River Structure B in Cheboygan County.

Energy officials say many dams cost too much to operate. Consumers Energy announced it’s exploring selling its 13 hydropower dams earlier this year.

As a result, the state and federal governments set aside tens of millions to fund removal projects in the last few years.

Moore said his team’s study is the first of its kind and could inform residents, land managers and local governments across the country.

“About a decade ago, you could claim that 99 percent of all the rivers in North America had dams at some point … What you're doing is slicing these rivers up and making them smaller,” Moore said. "As you make rivers smaller, they have the potential for the whole ecosystem to go extinct… but by connecting rivers, you restore it to its full glory.

“I would be a really strong advocate of removing dams to connect streams together, because that's the natural system. And that's what these organisms need to thrive.”

The study appears in the journal “Science of the Total Environment.” Moore says research will continue with specific studies on how fish and plant life were affected.

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