What’s Up with the Fencing Along Mill Creek Park?

By Doug Marrin

If you recently walked along the boardwalk of Mill Creek Park in downtown Dexter, you probably noticed some fencing along the riverbank.

Why? That was the question brought to my attention on the Facebook group, Friends of Dexter.

“The fencing was installed at the recommendation of the Landscape Architect that designed Mill Creek Park,” Interim City Manager for Dexter, Justin Breyer, explained. “It was installed because beavers have taken up residence in the stream that leads into Mill Creek Park, and they have been gnawing on the trees and bushes in the landscaped areas of the park.”

Breyer explained that in October or November, representatives from Ann Arbor Trout Unlimited reported beaver activity in a grove of trees upstream from the park. “But it has only been the last couple of months that we have noticed the damage to the trees and shrubs in Mill Creek Park,” said Breyer.

Damage to the young plants could kill the vegetation

Little did I know that checking into some chicken wire installed to protect the young vegetation would lead to a much bigger story.

From 1824 until 2008, Mill Creek in Dexter lay under 20 acres of stagnant pond water. When Judge Samuel Dexter established his namesake settlement, he built a dam on a fast-moving section of the creek to power his sawmill, which later became a gristmill. Although rebuilt many times, there was a dam there until 2008. Henry Ford bought the old Mill Creek dam in 1929, replacing it with a stone dam to generate electricity for a small auto parts factory he planned to build in Dexter. The Great Depression hit, putting those plans on hold.

Mill Pond, date unknown. Courtesy Dexter Area Historical Society

In 1995, a recommendation from the MDNR suggested opening up the dam. By then, the pond had become a nuisance, filled with algae and bugs. The Village Council enthusiastically embraced the idea. The question was where to get the money.

The answer came ten years later when the bridge over the dam began to fail. In April 2005, MDOT allocated money to replace the aging bridge. The problem was that the bridge was structurally tied into the dam. But, who was responsible for the dam? Ford was the last owner on record. Did the car company own the dam? MDOT built the bridge. Did MDOT own the dam? Scio Township? Washtenaw County? Dexter? Nobody wanted to take ownership of a deteriorated dam. In the end, Dexter agreed to pay $270,000 to remove the barrier.

The next issue was the contaminated sediments that had collected on the bottom of the pond. Michigan’s Department of Environmental Quality found that the contaminant levels were low enough that removal was unnecessary. The dam was removed, and the sediment was dredged and deposited onto the east bank. It was then covered by a foot of clay and six inches of topsoil. The four acres were landscaped and a boardwalk constructed. In 2012, the parcel was opened as Mill Creek Park.

Rabbits and deer are the biggest threat to young trees and shrubs. Once the vegetation has grown large enough to withstand foraging, the trees and bushes will provide a sustainable food source for wildlife. Beavers generally are not interested in smaller vegetation.

In September 2019, the City added a one-mile extension to the boardwalk. The new trail follows Mill Creek through the scenic wetland and then turns away to its terminus on Baker Road. The area is a popular spot for pedestrians, cyclists, and anglers.

I caught up with one angler, Mike Mouradian, while he was fly fishing on Mill Creek. Mike is a former president of the conservation group, Trout Unlimited Ann Arbor Chapter. He gave some background on how the group got involved when the dam was removed by monitoring the water to see how it affected the ecology. What they found was surprising.

Mike Mouradian, former President of Trout Unlimited Ann Arbor Chapter, is one of many anglers who enjoy the rejuvenation of Mill Creek into a vibrant ecosystem

“As it turns out, Mill Creek is a cold-water creek which is extremely rare in Southeast Michigan,” explained Mouradian. “Usually, you don't get cold water creeks until you're up in northern Michigan.”

The source was traced back to several places, with one as far away as Manchester. In its field study, Trout Unlimited discovered an unusual phenomenon feeding the creek—agricultural tiling, which keeps fields drained for farmers. In the watershed for Mill Creek, the tiling wasn’t just delivering runoff. It was pulling up fresh groundwater and feeding it into the creek.

Trout Unlimited is a conservation group that works to restore wetland habitation. The group planted this grove of trees that once grown will create bank stabilization and shade for Mill Creek.

“Trout Unlimited checked with the DNR, who confirmed the water, now restored to its original creek, was cool enough for trout,” explained Mouradian. “The only question then was whether the City wanted a trout stream running through it. It could be a real attraction and economic driver.”

The conservation group began stocking the creek with brown trout. The fish did well, even during one of the hottest summers on record. The DNR has since taken over stocking Mill Creek with trout, which have now begun reproducing, making the river a fish hatchery. Trout Unlimited has turned its energy to habitat restoration.

“This is a lot of background to explain what’s going on with the fencing,” said Mouradian, “but it’s important to know this project isn’t something that has occurred overnight. A lot of work and money has gone into restoring Mill Creek to what it once was.”

The two groves where the beavers are active. Keen eyes can spot the fallen trees with the characteristic beaver cut with more waiting to fall.

And what it once was, almost 200 years ago, was a cold creek with vegetation creating stabilized banks and shady spots. Trout Unlimited and the City of Dexter are working to restore those conditions, albeit with a 21st-century pathway.

As part of its habitat restoration efforts, Trout Unlimited recently planted a large grove of saplings along the bank of Mill Creek, easily seen from the walking path. The trees will provide shady spots for the fish and help keep the water cool. The tree roots will stabilize the bank by helping to prevent erosion. But this is only if the trees mature. While the trees are young and vulnerable, wire fencing surrounds each one protecting them from deer and rabbits who love to strip the bark off tender young trees. Once the trees are big enough to survive, the fencing will be removed, providing wildlife with a sustainable food source.

Although he is not working with the City on the fencing erected in the park, Mouradian speculates the same may be true there. Once the new vegetation is viable enough to withstand wildlife feeding, the fencing will probably be removed. The park shows evidence of rabbit, deer, and beaver activity.

The industrious beavers have set their eyes, or teeth, on the pilings that support the observation deck on the Mill Creek boardwalk.

Beavers have set up camp in two groves along a tributary of Mill Creek. You can see these groves from where the new trail begins at Forest Lawn Cemetery. You can see the felled trees with the characteristic beaver cuts and more ready to fall if you look carefully. Beavers don’t chew a tree until it falls. The rodents chew until the tree is significantly weakened and then let the wind do the rest. After the fall, the beavers get busy stripping off the branches, eating the bark, twigs, and buds, using the sticks for their dams.

Regarding the beaver dams in the two groves, Mouradian says that ways are being explored to harmonize with the beavers so that a stagnate Mill Pond doesn’t return. One method he described is the use of pipes running through the dams that would allow water flow, keeping the dam intact.

Until something can be figured out, preventative measures have been taken.

“If you visit the Park and look at the base of the trees and bushes, you will see evidence of chewing/scraping,” says Breyer. “The fencing was installed to give us time to evaluate the situation and determine what the next best course of action is in managing the beaver situation.”

“We’re just trying to restore Mill Creek,” Mouradian chuckles. “We never thought we’d have to learn about beavers too.”