There are more than 60 native fish species that can be found in the Cottonwood River watershed. Of that number half of them are not being found upstream of a series of dams that were erected in the portion of the river located in Redwood County.
In an effort to enhance that fish ecology upstream, the Minnesota Department of Natural Resources (DNR), began focusing a few years ago on making a change. Those efforts led to the allocation of funding to the DNR that would be utilized to remove three dams in the Sanborn and Lamberton area, as surveys have demonstrated those dams have hampered the movement of those fish species.
After conducting a series of meetings with residents of the two Redwood County communities to talk about the project, the DNR, in conjunction with Redwood County, began moving forward with the plan for removal of the dams.
That plan would include Redwood County serving in the role of fiscal host for the project, with the funding in excess of $1.2 million being used for everything from the engineering of what would be installed as a replacement of the dams to the construction work to remove the actual structures.
According to Scott Wold, Redwood County environmental office director of planning and environmental services, the county put out a request for qualifications and hired Houston Engineering of Fargo, N.D. to engineer the project.
Once the engineer was hired, then the process of finding the company to do the actual removal and installation work needed to be conducted. That company is Mathiowetz Construction, said Wold, and the work on the projects officially began Jan. 20.
At the Kuhar Park location seven riffles are being installed as the dam is being removed. The amount of drop from the first riffle to the last is intended to be the equivalent of what was happening with the dam.
Wold explained that the riffles are set up to direct the water toward the middle of the river. As that water flows the idea is that larger plunge pools would be naturally created, which would become an ideal location for fish and fishing.
The new structures were developed with the guidance of Luther Aadland of the DNR, and Wold said the intent is to make the riffles look natural but also to be set up with the intent of serving the purpose for which the project is intended.
Yes, said Wold, the boulders are specifically placed in the water to create the ideal scenario for fish passage.
The cost of the construction work came in at just over $800,000, with the remaining funds used for engineering and design of the project.
In addition to the Kuhar Park location, the other two locations are at the Sanborn golf course and at the Sanborn park. Riffles will also be installed at the city park, while what is known as a weir, which is a small pervious structure that slows and releases water in a controlled manner, will be installed at the golf course site.
The dams at each location were showing signs of deterioration and age, and their removal will mean there is no need for future maintenance.
In the end, the goal is to provide grade control, bank stability, redirection of flows and stream habitat improvement as well as fish passage.
A completed project will also have a much more aesthetic look than that of a dam.
River levels will not change and the natural look will mean few will even notice anything different.
Wold said the plan is to have the work completed by mid-February – weather permitting.