Cass Lake is a beautiful 16,000 acre lake in northern Minnesota known for its abundant and large Walleye (Sander vitreus). The Upper Mississippi River flows from Cass Lake into Lake Winnibigoshish, and was historically a migratory pathway for walleye and other fishes. However, the Knutson Dam, built in the early 1900’s for logging, blocked fish passage between Cass Lake and the Upper Mississippi.
The deteriorating physical condition of Knutson Dam, an assessment of area watersheds, and the value of the fisheries in the lake and river made the Knutson Dam a priority for removal. Subsequently, the Forest Service in collaboration with the Midwest Glacial Lakes Partnership, Minnesota DNR, Leech Lake Band of Ojibwe, and the Army Corp of Engineers developed the Knutson Dam Improvement Project plan.
In 2015, the Knutson Dam structure was removed from the Mississippi River channel, restoring fish passage on the main-stem of the Mississippi River. This improved the hydrologic function of the Upper Mississippi River by installing a fixed-crest rock weir and rock rapids structure for water level management of the Cass Lake Chain. The new rock rapids structure restored fish passage in over 30 miles of the Mississippi River, its tributaries, and also inclusive of 72,000 acres of lakes. This is critically important in the restoration of migration routes for most warm water fish species on and between Cass Lake and Lake Winnibigoshish. The riffle habitat that replaces the dam will provide spawning habitat for fish species such as Walleye and White Sucker (Catostomus commersonii).
The removal of the dam also reduced lakeshore erosion on Cass Lake by minimizing the duration of high water periods, because the new structure allows higher flows during high water. Furthermore, the new structure improved recreational opportunities at the site; there is a popular Chippewa NF campground adjacent to the Cass Lake lakeshore and Mississippi River channel. Visitors will now be able to access both Cass Lake and the Mississippi River safely, fish off the banks and pier, and enjoy the more natural appearing lake, river and shorelines.
For more information and videos of the project, check out the links below!