Over the past few years, the Department of Natural Resources has assisted in the removal of abandoned, unsafe or unnecessary dams at a rate of four or five annually. Many of the 2,500-plus dams on Michigan's rivers are aging and have outlived their useful function, so it makes little sense to put money into them.

Most dams in Michigan were built to power mills or produce electricity; very few were built for flood control. But as power-generating methods became larger and more economical in the last half of the 20th century, the vast majority of Michigan dams were retired from power generation. As a result, they were neglected.

However, because of recent changes -- both in terms of higher energy prices as well as a social desire for renewable energy -- a lot of folks began looking at the feasibility of putting hydroelectric facilities back online. If renewable power can be produced economically without polluting the environment, could we see a return of small hydroelectric facilities to Michigan?

"If they're not serving a function, we'd just as soon see them removed," said Chris Freiburger, a fisheries biologist at the Department of Natural Resources who is in charge of reviewing requests for hydropower generation, administered by the Federal Energy Regulatory Commission.

"We have seen several communities get excited about the possibility of returning an old dam to hydropower production, only to find the cost of retrofitting and the complexity of federal licensing requirements cannot be offset by the revenue generated by the power production," he said.

Michigan's topography does not offer much relief beyond a few hills and valleys, so it's just not practical to generate power in the Midwest the same way it is in the West. The past practice of holding water in a large reservoir to boost the generating capacity of that stored water also is no longer acceptable.

"Peaking operations are pretty much obsolete in Michigan," Freiburger said. "Current hydro facilities are operated on a 'run-of-river' mode because of the adverse impacts of peaking operations."

Funding is more readily available for dam removal than power generation. Although would-be hydro operators are on their own to pay for federal licensing standards, there are several potential sources of funding to remove dams because of the environmental benefits.

Foundations and governmental grant programs aimed at river restoration are keen on dam removal, and DNR fisheries managers have long advocated for free-flowing, functioning river ecosystems, rather than the dams and impoundments that change the character of rivers.

"Healthy rivers move their sediment load, they move the woody structure that falls in them, and they move water -- that's all part of a healthy habitat," said Freiburger. "If we have healthy habitat, our entire aquatic community will benefit."

Removing barriers such as dams allows for fish passage, both upstream and downstream. Freiburger continued.

"We've long known that fish movement is important for salmonids, but it is for our resident species, too, to be able to spawn, to be able to feed and to find nursery habitat," he said. "Fish have to move daily, seasonally and annually to meet their life history requirements."

According to Freiburger, not all dams need to be removed; some can be modified to provide the fish passage and flow that will help the system function in a healthy way. But every removal or modification of a dam is a unique situation, and the optimal treatment demands an on-site study to make sure the cure fits the symptoms.

Take the dam on the Potagannissing River on Drummond Island for instance. Located about one and one-half miles upstream from the bay, the dam originally was built as a waterfowl flooding, but it wasn't producing the benefits for which it was designed. So DNR staffers worked with members of the Potagannissing Sportsmen's Club to modify the structure. They removed two-thirds of its height and constructed rock rapids below the remainder of the dam to allow fish passage upstream into lakes and wetlands to serve as spawning/nursery areas. Modifications were completed in September 2006.

"The following spring, crews set nets and found perch, walleyes, pike and suckers upstream," Freiburger said. "It's working."

Completely removing dams, however, generally isn't as simple as knocking them down and hauling away the debris.

"At one extreme, you can completely remove the dam and walk away and let the river restore itself," Freiburger said. "That's rare. Typically, it takes other forms of management. In some cases, you put in rapids and rebuild the channel upstream to minimize the amount of sediment you move downstream."

When local officials decided to remove a dam on the Grand River at Dimondale that was built in the late 1800s, the plan called for building a set of rapids behind the dam, before removing the structure.

"We estimated there was 180,000 cubic yards of sediment behind the dam," Freiburger said. "We wanted to hold that sediment in place, but allow any new sedimentation to flow downstream. They had widened the river to get material to build the dam, so we went in and rebuilt the channel using a natural-channel design so the stream could transport the sediment load as it is supposed to."

Municipalities often obtain inland fisheries grants from the DNR to help with dam removals.

"The U.S. Fish and Wildlife Service, through its fish passage program, has been a good source for funding dam removals and culvert installations," Freiburger said, "but municipalities have to provide some funding to qualify for the grants.

"And some user groups -- sportsmen's groups, conservation clubs and private foundations have been very helpful, too."

In many cases, the cost of removing a dam is not as large a stumbling block as the structure's history.

"The most difficult part of getting a dam removed is the social aspect of it," Freiburger said. "The oldest folks in town remember it always being there. People have memories of fishing behind those dams or otherwise using them, so it's hard for them to conceptualize how a restored river system is going to look -- they're afraid it's going to dry up to a trickle and leave a large mud flat behind. And now we've got people convinced we can restore power generation at some of these locations."

Freiburger said if power generation were still economical, it's unlikely that Consumers Power and Detroit Edison would have divested themselves of the hundred or so dams they had in the 1960s.

"Those dams were retired from power production for a reason," Freiburger explained. "And in the 40 years since, those dams have done nothing but go downhill."

Michigan is rich in streams and rivers. It seems fitting that we let that natural beauty be the economic driver of the future and find our energy needs elsewhere.