Each winter, thousands and thousands of bats hibernate inside Tippy Dam on the Manistee River. And the bats inside Tippy Dam are special: They’ve managed to survive an epidemic that’s wiped out bat populations across eastern North America. But no one knows why.
Consumers Energy will hold a public meeting to discuss the future of Tippy Dam and Hodenpyl Dam on the Manistee River from 6-7:30 p.m. on Monday, Dec. 15 at Crystal Mountain Resort in Thompsonville.
Now, Consumers Energy, which owns Tippy Dam along with 12 other hydroelectric dams in Michigan, has struck a deal to sell the dams to a Maryland-based private equity firm.
So, where does that leave the bats and the humans who study them? That's what Allen Kurta is wondering.
Kurta is retired biology professor at Eastern Michigan University. For many years, his job involved a lot of driving around Michigan trying to find bats. In the 1990s, he heard a rumor that a bunch of bats were hanging out inside a dam up north. So he made the four hour trip to check it out.
"I went with a grad student of mine," he said. "All the way up there, I kept saying, 'Joe, I just hope there's 50 bats to make this worthwhile.' And we get up there, and we're just floored, because there's more than 10,000 bats inside that spillway."
Kurta eventually counted around 20,000 bats inside Tippy Dam. At the time, most of Michigan's bats hung out in abandoned mine shafts in the Upper Peninsula. So to find that many bats in the Lower Peninsula "was just a terribly exciting experience," Kurta said.
Fast forward a couple decades to 2014: a deadly fungal disease called white-nose syndrome starts sweeping through bat populations in eastern North America, including Michigan.
"That introduced fungus resulted in the collapse of our hibernating bat populations, so that 90 percent of the bats that hibernated in those [U.P.] mines are dead," Kurta said.
In warm temperatures, white-nose syndrome is not a problem for bats. But when a bat goes into hibernation, its body temperature drops to a range that's ideal for the fungus to grow. It attacks the bat's skin, awakening the animal from hibernation early. Infected bats leave to look for insects, but there are none, and those bats often die out on the landscape, Kurta said.
Kurta and his colleagues eventually found the presence of the fungus inside Tippy Dam. When they went back, they expected to see 10,000 fewer bats. But that's not what they saw; the bats were still there.
"It was just odd," Kurta said. "And [we thought], "OK, well, you know, the disease hasn't really taken hold yet." So you go back the next time and they're still there, and you go back the next time and they're still there. That was just amazing."
A decade later, Kurta said, Tippy Dam is now the largest hibernating colony of bats in Michigan. The little brown bats who live there, a species whose numbers have been reduced by over 90% from white-nose syndrome elsewhere, are doing just fine in Tippy Dam.
"There is something going in in that dam that is allowing them to survive the infection," Kurta said. "So it's an important natural resource, and it does a world of good for farmers and everybody else by eating insect pests and things that transmit diseases."
It's also a source of interest for researchers like Kurta, who want to find a solution to white-nose syndrome.
"There's the possibility of discovering something that might help populations in other parts of the world not collapse," he said.
To do that research, Kurta has relied, for decades, on Consumers Energy to let him access the dam, which they've done as a courtesy.
Brian Wheeler, a spokesperson for Consumers Energy, said, "We're committed to continuing to have this location be open and accessible for this research to take place."
But if the 13 hydroelectric dams owned by Consumers sell, the question of access will be up to a new company.
Confluence Hydro, the company tentatively purchasing the dams for $1 each, said in an email that it plans to operate the dams "in accordance with the same species protections Consumers Energy has undertaken. We further understand the importance of bat research underway at the Tippy Dam, and we look forward to learning more about how we can support these efforts."
The sale of the dams is already facing some complications. The dams are old — Tippy Dam was built over 100 years ago — and expensive to maintain.
Tippy Dam, along with a few other Consumers Energy dams, is not meeting water quality standards, which could slow down the approval process for the sale.
And old, poorly maintained dams pose other problems. A pair of mid-Michigan dams failed and flooded in 2020. Now, taxpayers are footing the bill to rebuild.
The idea of removing Tippy Dam and returning the Manistee River to a more natural state has been floated in the past.
Dam removal or failure could could destroy a refuge for bats who've survived white nose syndrome in Tippy Dam, and the answer to what's keeping them alive.
Regardless, in surveys of residents living near Tippy Dam, the majority wanted the structure to remain in place. And when Consumers Energy announced the sale of the dams in September 2025, the company wrote it was "confident this sale [would] preserve the reservoirs" created by the dams.
The sale of those dams is still pending approval.
