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Posted on: November 15, 2018

Freeborn Lake Update

Arrowhead 5

Efforts to improve water and habitat quality in Freeborn Lake continue.  Through a joint project between Freeborn County and Ducks Unlimited, Inc. the County Highway 6 culvert on the Cobb River and Freeborn Lake dam have been replaced with new structures.  


The County 6/Cobb River crossing was replaced in summer 2017 with a new culvert having flow characteristics to keep rough fishes from reaching the lake.  In late 2017 the dam was replaced at the outlet of Freeborn Lake.  The full service level of the new dam will be at the level maintained by the old dam.  However, the new dam has stop logs to allow flows and lake levels to be manipulated to improve water quality.  Minor finish work and reseeding was completed in late summer.  


Freeborn Lake benefits from occasional periods of low water as occurs naturally during times of drought.   Lower water levels facilitate removal of rough fish, help consolidate and oxidize lake sediments and encourage beneficial plants to grow from seed.  By removing stop logs, natural resource managers can lower lake levels and emulate the effects of drought.  


A lake drawdown began in conjunction with dam construction.  In early winter lake levels were lowered further by Department of Natural Resources (MNDNR) staff to help induce a freeze-out of rough fishes.  Fishing regulations on the lake were relaxed through the end of February to allow anglers to exploit existing fish populations. The freeze-out appeared to be fairly successful and test nets and traps set in summer yielded few fish in the lake.  


In early spring some stop logs were returned to the dam allowing water levels to partially recover to about 24- 30 inches below normal.  The growing season drawdown allowed a fringe of emergent plants (rushes, cattails, etc.) to grow around the outer edges of the lake. Submersed plants established and grew underwater, eventually being found in most of the basin.  By mid-summer water clarity was greatly improved from previous years and water chemistry measures also document improvements.  


As undesirable fish populations can prove difficult to eradicate a second winter drawdown will be planned for 2018-2019.  Next spring and summer, as plants mature, lake levels will be returned to normal given adequate precipitation and runoff.    


The MNDNR plans to restock Freeborn Lake with northern pike and yellow perch to provide fishing and help support water quality and habitat objectives.  These species are adapted to shallow lakes.  They are expected to grow fast and benefit from cleaner water and habitat improvements.  Northern pike fry were stocked in spring of 2018, but no perch were added due to the late ice-out and uncertainty of the extent of the winterkill at that time.  Additional stocking is planned for spring 2019.      


Freeborn County and MNDNR are also cooperating on the water access at Arrowhead Park.  Improvements to the ramp and launch site were completed in 2017.  


The LeSueur River Watershed Network and Freeborn Soil and Water Conservation District continue to be active in watershed restoration activities and are working to identify and implement strategies to improve water quality.  This network also provides a pathway to organize efforts to educate and take action to improve watershed health.  Watershed efforts to conserve soil health and improve water quality will compliment “in-lake” management actions.  


The rehabilitation project for Freeborn Lake is a cooperative venture made possible by Minnesota’s Outdoor Heritage Fund. The majority of the funding for the culvert and dam replacement is from grants obtained by Ducks Unlimited, Inc. to improve degraded shallow lakes in Minnesota.  Ducks Unlimited also provided engineering and construction oversight.  Freeborn County owns the new structures.  The MNDNR will be responsible for habitat and fisheries management efforts.  Additional information can be found on line at http://www.co.freeborn.mn.us/381/Future-of-Freeborn-Lake.


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