Eastern Region - R9
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Milwaukee, WI 53202
Phone: (414) 297-3600
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 Environmentally friendly fuels were used during the removal process, and oil and gas booms were installed downstream to capture any spills. Newsroom
News Release
USDA Forest Service
Eastern Region
23-Sep-2004
Local Contact: Cathy Fox 715-362-1362
A Good Dam Job
In 2001, the Chequamegon-Nicolet National Forest entered into preliminary discussions with the Wisconsin Department of Natural Resources (WDNR) for the purpose of improving fisheries habitat in the North Branch of the Oconto River, located on the Lakewood-Laona Ranger District.
These discussions became reality in 2004 as work began to remove the remnants of the Hemlock Dam.
The Holt Lumber Company, who had considerable land holdings in the area, constructed the Hemlock Dam in 1894. The dam was instrumental in creating the conditions necessary for floating pine logs downstream to sawmills along the Menominee and Oconto Rivers.
During the early pinery days, this was the only method used to bring logs to the mills, where they eventually became lumber used for home and industrial development. An estimated 75 logging dams were constructed on the Forest during this time.
Later, the railroad became the primary method of transportation, and, in most cases, the dams were abandoned or dismantled. Historical records indicate the Hemlock dam ceased operation around 1896.
The Hemlock dam was a crib dam. A crib dam usually had one, and possibly two, rubble-filled wooden cribs. The cribs served to anchor a wooden framework that probably included two wooden gates, one functioning as a floodgate, and the other functioning as a sluicing gate. Each gate was raised and lowered by a crank and gear mechanism. One of the old gear mechanisms was recovered at the dam site.
Although water was abundant in northern Wisconsin’s expansive river systems, river flow was unpredictable, so logging dams were constructed to create reservoirs that ensured adequate water volume for log driving. The log drives had a substantial impact on rivers throughout the area.
Rivers were “cleaned” of wood and rocks to make log driving easier, but this removed valuable habitat for fish and other aquatic organisms. And the release of water from logging dams caused floods that in some cases scoured the bed and banks of rivers, reducing fish habitat by causing the rivers to become wider and shallower.
The remnants of these old dams were also having a negative impact on the river by constricting the channel and causing water to pond upstream. The constriction is caused by earthen dikes that still cross the floodplain and low rock sills that remain within the river channel.
The upstream ponding of water causes the channel to fill with sediment, becoming wider and shallower and warming the water. Provided the dam does not have historical significance, removing the remnants can result in substantial river restoration.
Mark Bruhy and Kim Potaracke, Heritage Resource staff on the Forest, conducted an evaluation of the Hemlock Dam. It concluded that the dam did not retain sufficient integrity to meet the National Register of Historic Places eligibility criteria.
Following the environmental analysis and public scoping for the removal of the dam, the Forest Service and WDNR entered into a joint agreement that involved a two-phase process for removing the remnants and restoring the streambed.
In July 2004, phase one began.
This involved the removal of two earthen berms (dikes), rock and cribbing. Although the remnant rock sill only raised the upstream water level two feet, this caused water to pond upstream nearly two miles, causing a wide, stagnant channel with warm water.
Removal of the sill lowered the water level about one foot and has begun the process of restoring the river to a narrower, deeper channel with more current and cooler water. A temporary earth pad along the south side of the plunge pool below the dam site was pit in place. This pool will act as a sediment basin for up to five years
In 2005, additional work will be conducted to further lower the water level upstream to its original level.
The WDNR is the major cooperator for this project, paying all costs for on-the-ground removal as well as coordinating and obtaining all necessary permits for the work to take place. The WDNR also brought in a crew that specializes in dam removals and restoration.
While not financial contributors, the River Alliance of Wisconsin and Trout Unlimited has been very supportive of this project.
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