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Netting Carp for Cleaner Water in the Six Mile Creek Chain of Lakes

November 8, 2018

Eric releasing a carp into the waterIt’s been a busy few months in the Six Mile Creek chain of lakes, where the Minnehaha Creek Watershed District and its partners have been hard at work reducing the number of common carp that are in the system. It’s the first phase of one of the metro’s largest habitat restoration projects, funded by a $567,000 grant from the Lessard-Sams Outdoor Heritage Council. The focus of the restoration is the Six Mile Creek – Halsted Bay Subwatershed, which is the headwaters of Lake Minnetonka and includes five impaired lakes and Halsted Bay, Lake Minnetonka’s most degraded bay.

We are focusing on invasive common carp first because of the damage they cause and the availability of proven, cost-effective management strategies to control their numbers. Common carp uproot plants and stir up lake bottoms, which degrades habitat and releases nutrients that feed algae blooms. Reducing their numbers in lakes helps protect water quality and improves habitat for gamefish and waterfowl.

The carp management plan is based on data from a three-year study by the University of Minnesota’s Aquatic Invasive Species Research Center. The research team assessed the number of carp in the Six Mile Creek chain of lakes, identified their spawning locations, and determined their migration patterns. The findings helped shape a management strategy that includes removing adult carp, installing carp barriers, and aerating lakes to ensure the winter survival of bluegill sunfish (which feed on carp eggs).

So far, our staff have been working to remove adult carp using baited box-net traps. This was very successful on East and West Auburn and Steiger Lakes with 13,234 lbs removed so far. We did not net as many carp on Wassermann Lake, which indicates the carp population there is near the target number. That’s likely due to a temporary barrier that is stopping carp from entering from the lake’s outlet.

Now that the weather is turning colder, carp are starting to move to deeper water. In order to track their movements, staff have been electrofishing on lakes, implanting radio tags into the carp that are caught, and releasing them back into lakes. The radio-tagged carp will aid our carp removal efforts this winter. Overall, our goal is to remove 872,000 lbs of fish across 12 lakes, so we’re already making great progress!

We have also made progress on installing carp barriers, which block carp access to spawning locations. We currently have three temporary barriers up: one at Highland Road east of Mud Lake, one north of Crown College Pond, and one north of Wassermann Lake. If all goes as expected, permanent barriers should be installed this winter before carp start migrating in the spring.

Managing carp is just the first strategy in a multi-pronged ten-year effort to improve water quality in the Six Mile Creek – Halsted Bay Subwatershed. We are focusing on this area because of the unique opportunity to protect and improve water quality while the land use is changing. We are working with a multi-jurisdictional partnership made up of the Minnesota DNR, Carver and Hennepin Counties; Laketown Township; the cities of Minnetrista, St. Bonifacius, Victoria and Waconia; and Three Rivers Park District to coordinate our goals early so that changes on the land are planned in a way to also benefit water quality. This type of proactive collaboration is innovative in the world of land use and water planning, and we hope it will serve as an example of how partnership and early coordination can create thriving communities that protect ecological integrity.

Learn more about the Six Mile Creek – Halsted Bay Subwatershed.