Failing Dams at Crooked Creek Preserve to be Removed

The Nature Conservancy in Wisconsin Will Restore Headwaters of the Mukwonago River

EAST TROY, Wis. — September 30, 2008 — The Nature Conservancy today announced that it would soon begin work to partially remove two half-century-old dams at its Crooked Creek Preserve. The dams are considered unsafe, and they have impacted the ecological health of the Mukwonago River by altering the river’s flow and raising its temperature. The Conservancy will restore the land and water around the dams— including springs that constitute most of the river’s headwaters—to their historic natural condition.

Water will soon be drawn down from artificial ponds created behind the dams. A contractor is then expected to start removing much of the dams themselves. The dams have been compromised with numerous holes from tree roots and muskrats. The project area will be reseeded later this year to prevent erosion and to plant a diverse mix of native plants.

“An extreme rain event could cause the dams to fail,” said Hannah Spaul, who directs the Conservancy’s land management work in Wisconsin and who is overseeing the dam removal and restoration work at Crooked Creek. “That would lead to extensive flooding downstream—endangering highly significant and sensitive natural areas including Lulu Lake State Natural Area and impacting the quality of water within the river.”

Tom Day, chair of the Eagle Springs Lake Management District, said he welcomed the Conservancy’s efforts to restore the site, where much of the Mukwonago River begins, to its original condition. “We’ll have a more natural flow of cold water into the river and that will benefit the fishery and the whole system,” he said.

Day also expressed relief that the dams would be taken down. “Those dams were not in the best condition. I was concerned in June that they would give way. That would have added to the flooding situation that was already occurring in the watershed,” he said.

Tom Slawski, a stream ecologist who reviewed the project as principal planner for the Southeastern Wisconsin Regional Planning Commission’s environmental division, said that the dams placed important wildlife species and natural communities at risk.

“First and foremost, there was a real danger of those dams failing,” he said. “That would have been pretty devastating.”

Slawski also said that the Conservancy’s work at Crooked Creek will benefit the river’s native fish by allowing them to move upstream and spawn in a naturally-functioning wetland and by restoring the river’s natural water temperature.

“Reconnecting the headwater springs to the river should lead to an increase in the abundance and diversity of native fish, particularly cold-water species,” he said.

Ezra Meyer, vice president and a founder of Friends of the Mukwonago River, said he applauds the Conservancy’s efforts to restore the river at its source. “This will benefit native plants and wildlife. The best place to start in river restoration is the headwaters and then you move on down,” he said.

The Conservancy also consulted with the Wisconsin Department of Natural Resources, the U.S. Fish and Wildlife Service and the Natural Resources Conservation Service on the project.

The work is expected to cost about $150,000 and is being paid for with a mix of state and federal grants as well as private money.

Crooked Creek Preserve will continue to be open to the public for hiking, birding and hunting during and after the restoration work. However, access in and around the dam sites may be limited while the work is in progress.

The Nature Conservancy is a leading conservation organization working around the world to protect ecologically important lands and waters for nature and people. The Conservancy and its more than 1 million members have protected nearly 120 million acres worldwide. In Wisconsin, the Conservancy has helped conserve more than 140,000 acres since 1960. The Conservancy has more than 21,000 members in Wisconsin and offices in Madison, Baraboo, East Troy, Minocqua and Sturgeon Bay. Visit The Nature Conservancy on the Web at nature.org/wisconsin.