Going with the Flow
Mill Creek is a whole new habitat
Sparkling in the sunshine on a perfect fall day, Mill Creek cascades over rocks and meanders through quiet pools as it flows toward the Huron River. Turtles sun themselves on rocks, and minnows dart through the water.
But from 1824 until this spring, no one had seen this half-mile section of Mill Creek near downtown Dexter. The creek was hidden beneath a twenty-acre stagnant impoundment pond filled with algae, water lilies, and invasive purple loosestrife. This year the Village of Dexter spent $270,000 to get rid of the old dam that had formed the pond.
Locally and across the nation, dam removal is a hot topic. Environmentalists say it improves the health of rivers and opens up prime habitat and spawning grounds for native fish. But removing a dam can also release polluted sediment and change drainage patterns in ways that can cause problems downstream. Taking out dams means more streams for canoeing and kayaking but fewer lakes for boating and sailing. And the cost can swamp most local budgets.
Most of Michigan's 2,500 dams are old and need major repairs. So, like Dexter, many other communities will soon have to decide whether to fix an old dam or take it out. Either way, it won't be easy.
It certainly wasn't easy in Dexter. It took thirteen years to figure out who owned the dam, find money to remove it, deal with contaminants in the pond, and negotiate a maze of federal, state, and local regulations.
In the end, persistence, hard work, and community support paid off. So it's understandable that Dexter residents are proud of the pretty stream that now runs along the western edge of their village. And no one is more proud than Paul Cousins.
"It's exactly what it looked like originally," says Cousins as he walks along the banks of Mill Creek. "It's the natural channel."
Cousins has been the point man for the Mill Creek project since 1995. An energetic seventy-year-old with a full head of silver
hair, he's been a fixture in Dexter since the 1960s, when he came to teach high school biology and environmental studies. After retiring from teaching in 1984, he ran Cousins Heritage Inn for twenty-one years. Along the way Cousins has served several terms on the Dexter Village Council and was a leader in the campaign to purchase and preserve Gordon Hall, judge Samuel Dexter's historic home.
When Dexter established his village in 1824, he picked out a fast-moving section of Mill Creek and built a dam to power a sawmill and later a gristmill. There's been a dam there ever since. It's been rebuilt or reinforced many times over the years.
In 1929 Henry Ford bought the old Mill Creek Dam and the land around Mill Creek Pond behind it. He built a new seventy-foot-wide stone dam to generate electricity for a small auto parts plant he wanted to build in Dexter. The factory was put on permanent hold when the Depression hit.
In the 1930s and 1940s Mill Creek Pond was a popular spot for canoeing and boating. By the early 1990s, though, the pond was nearly filled with algae and had become a local eyesore. So when the Michigan Department of Natural Resources Fisheries Division recommended, in a 1995 report, that Mill Creek Dam be removed to open up the Huron's largest tributary, the village council enthusiastically agreed.
Finding the money, however, was a major problem. And then came the final straw: Main Street Bridge, built in 1932 next to the dam, began to fail.
In April 2005 the Michigan Department of Transportation approved funding to replace Mill Creek Bridge and seventy-five other bridges. When Washtenaw County Road Commission engineers inspected the bridge in the spring of 2007, they found more deterioration and lowered the bridge's weight limit from ten tons to seven. School buses could no longer cross it. The bridge had to go.
But replacing the bridge meant dealing with the dam.
"We found out that the dam was integrally tied into the bridge itself," Cousins says. "So we said, 'If you put a new bridge in, you will have to construct a new dam. There's no money for constructing new dams. So why not just take it out?'"
The most important reason for removing aging dams is to improve the health of rivers, says Laura Rubin, executive director of the Huron River Watershed Council. Dams raise water temperatures, reduce water-borne oxygen that fish breathe, and prevent streams from flushing out pollutants and sediment.
Dams also interfere with migration patterns and life cycles of fish, insects, and microorganisms, says Paul Seelbach, a research biologist at Ann Arbor's Institute for Fisheries Research, a partnership between the U-M and the DNR. Dams are in areas where elevation drops sharply and water moves rapidly-prime fish habitat. "We should look at the costs and benefits of every dam," Seelbach says. "When the costs outweigh the benefits, we should take them out."
According to a 2007 report from Lansing's Public Sector Consultants, there are 2,500 dams in the state, 93 percent of them more than twenty-five years old. Most dams have a life expectancy of about fifty years.
Costs of dam removal can range from $50,000 to millions of dollars, according to Rubin. "A lot of communities are struggling with these aging dams," she says. "What do we do with them? In many cases, people are just abandoning them or handing them over to the DEQ and saying, 'You take them. I don't want them.'"
The Huron River watershed is the most heavily dammed river system in the state, with ninety-six dams. There are eight dams on the Huron downstream from Dexter. Most were built in the 1910s and 1920s by Detroit Edison (now DTE Energy) to generate hydroelectric power. From the 1940s to the 1970s, many smaller dams were built on tributaries by communities or home owners' associations to form recreational lakes, to regulate water levels, and to control flooding.
Over the years, ownership of these dams changed hands as people bought, sold, and transferred property. For many dams, there is no clear documentation of these transactions. But since the owner is legally responsible for maintaining or removing the dam, the question of who owns it has serious financial and liability ramifications.
When the Village of Dexter started working with state DEQ officials to demolish Mill Creek Dam, it started a political game of hot potato to determine who owned the dam and who would have to pay to remove it.
Since Henry Ford was the last owner of record, did Ford Motor Company still own the dam? Corporate attorneys said rights to Mill Pond and the land around it had been returned to the village and local property owners years ago.
Since the Michigan Department of Transportation built the old Mill Creek Bridge in a way that made it part of the dam, did MDOT own the dam? Not a chance, responded state officials-they agreed to pay for a new bridge but didn't want responsibility for the dam. Similarly, the Washtenaw County Road Commission was willing to chip in for a new bridge and road but said the dam was not its problem.
Village officials kept pointing out that the dam was west of the village limits and not even part of Dexter. But Scio Township wouldn't pay to remove the dam.
The project might have died there, but Dexter wouldn't let it. After much wrangling, the village agreed to pay $270,000 to remove the dam and accepted responsibility for any contaminated sediments found at the bottom of Mill Pond. "We thought it was important for the citizens and for Dexter's future," says Cousins. "Without the support of the community and the village putting their money in here, it wouldn't have been done."
The big unknown was the condition of the sediments that had collected behind the dam. When environmental contaminants like PCBs, dioxins, or mercury are released into a river or stream, they latch on to bits of sediment in the water and settle to the bottom. If you take out a dam without first capturing and removing these sediments, the toxins flow downstream.
"If the sediments are contaminated," says Rubin, "you may have to dredge them out and haul them to a hazardous-waste landfill. If that happens, it takes the cost of dam removal to a whole new level."
When environmental consultants tested the sediment behind Mill Creek Dam, they found slightly elevated levels of arsenic and cadmium. Arsenic occurs naturally in the area, so it wasn't a big issue. But too much cadmium could kill single-celled organisms, insects, and fish. DEQ officials also were concerned that cadmium might move downstream to Ann Arbor, which gets its drinking water from the Huron.
Fortunately, additional tests found the contaminated area was smaller than anticipated, so the village had to remove less than half the sediment expected. And the level of cadmium wasn't high enough to require disposal in a landfill. Instead, the DEQ agreed that the contaminated sediment could be sealed on site. The source of the cadmium in Mill Pond remains a mystery-though Cousins says history buffs in Dexter suspect it came from tanneries near the pond.
This spring the village brought in URS Corporation, an environmental engineering firm with experience in dam design and removal. URS engineers and dam experts spent weeks examining every inch of Henry Ford's stone-and-concrete dam, which had been reinforced at some point with steel pilings.
After building a temporary road across Mill Creek, URS consultants moved excavating equipment in to carefully scoop out six feet of built-up sediment from the pond and spread it on the east bank of Mill Creek to dry out. It would later be covered with a foot of clay and six inches of clean topsoil, held in place by landscape plants and natural vegetation.
In May, when it was time to start taking out the dam, Paul Cousins was watching, camera in hand-along with a crowd of people lining the banks of Mill Creek.
"They came in and knocked some holes in the dam and took out about a foot in the center at first," Cousins says. "All of a sudden, the water stopped going over the dam and started running under the sheet piling and coming up on the other side. There was water gushing up about three feet high on the other side of the dam."
With fifty cubic feet of water per second flowing underneath the dam, the force of the water threatened the creek embankment and the new bridge abutments already in place downstream from the dam.
"The consultants decided the dam had probably eroded underneath before, but all that silt had filled it in," Cousins says. "When they took the sediment out, that space opened up again."
Working with officials from the DEQ, the consultants decided to reduce pressure on the dam by bringing the water level in the impoundment pond down faster than planned. The dam removal, expected to take six weeks, was completed in four.
Now that the dam is gone, Dexter residents are working on plans for a new park on reclaimed land the village has acquired on the east bank of Mill Creek. The park will run along the creek from the new bridge to Shield Road. Reclaimed land on the west bank of the creek will be returned to the neighboring property owners to be "kept in a natural state," says Cousins.
Paul Seelbach expects that pike, smallmouth bass, and walleye living in the Huron River will move into Mill Creek and spawn or spend the winter. Old records indicate that Mill Creek used to support a thriving population of native pike, and Seelbach says there's a good chance they'll return.
Always the visionary, Cousins foresees hiking trails and bicycle paths connecting Mill Creek to the Metroparks on the Huron. He pictures people in canoes and kayaks paddling up Mill Creek from the river to have lunch, anglers fishing from its banks, and families picnicking.
"It's satisfying, but not just for me personally," Cousins says. "I'm happy to see something good happening for the village."
As for Laura Rubin and her colleagues on the Huron River Watershed Council, they hope Mill Creek's story will help build community support for removing two other dams on the Huron River-Ann Arbor's Argo Dam and the Peninsular Dam north of Ypsilanti.
"These are the dams that, from a hydrologic and ecological point of view, we get the biggest bang for the buck," Rubin says. But it won't be easy. "The local rowing community is opposed to removing Argo Dam, because they use the impoundment pond extensively. Peninsular has about a dozen homes sitting right on the impoundment pond. People bought the house because it was on a lake. Now they'd be on a river with wetlands and fields in front of their house."
Every dam has its own unique situations, and building community consensus is an important part of the process. Creating public support to remove dams in Ann Arbor and Ypsilanti is likely to be much more difficult than it was in Dexter. But unless and until that happens, the political process-like water in a river-will take the path of least resistance.
[Originally published in January, 2009.]