Dane County Office of Lakes & Watersheds
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Aquatic Plant Management

Aquatic Plants

Large lake plants (called macrophytes) are an essential part of healthy lake and stream ecosystems. They are home to many aquatic animals and provide cover for young fish avoiding predators. Large lake plants also stabilize bottom sediments and reduce shoreline erosion.

Some rooted aquatic plants are weedy, especially exotic (non-native) plants, such as Eurasian water milfoil that first arrived in area lakes in the 1960s. Excessive growth of Eurasian water milfoil makes it the most abundant rooted plant in the Dane County lakes.

This canopy-forming growth characteristic is what makes Eurasian water milfoil such a nuisance to us. In particular, dense growth of the exotic plant interferes with boating and swimming, and the plants may produce an unpleasant odor when they die during summer. Eurasian water milfoil is usually the plant that lakeshore property owners, boaters and swimmers complain about, and with good reason. This weed (a "weed" is merely a plant out of place -- it is growing in the wrong spot) degrades the enjoyment and the ecology of the lakes.

As with many problem exotic species, we are unable to eliminate Eurasian water milfoil from Dane County lakes. The plant continues to flourish in our lakes because the bottom sediments are a repository of excessive loads of nutrients from urban and rural runoff over the last 150 years. The goal for the most effective management is to mechanically harvest the plants where they are at nuisance levels and take the cuttings for composting in gardens.

Dane County Nuisance Plant Harvesting Program

Dane County Land and Water Resources through its Parks Division manages an Aquatic Plant Harvesting Program for county waters, with support from the Dane County Office of Lakes and Watersheds. Harvesting follows permit requirements from the Wisconsin Department of Natural Resources and approved Aquatic Plant Management Plans for each waterbody. The Dane County Lakes and Watershed Commission, Dane County Parks Commission, and elected county officials provide oversight.

Dane County currently has a total of ten mechanical harvesters and assorted other harvesting equipment. The county hires seasonal limited term employees to perform the harvesting. The supervised crews harvest aquatic plants from mid-May until mid-August. Crews are trained to focus on areas with exotic plants and to avoid areas with more native aquatic plants.

Adhering to DNR requirements and operating within the county's limited budget, the county's policy is to cut and harvest Eurasian water milfoil and other invasives to help provide for reasonable use of the lakes for boating, fishing and swimming, while preserving the health and balance of the lake ecosystem. Harvested plants are hauled by truck to remote compost sites.

Current plant harvester locations and harvesting priority maps can be found on the Dane County Parks page.

For more information, see Aquatic Plants in Dane County Waters.

Aquatic Plant Management Plans

Aquatic plant management plans provide an inventory of existing plants in a lake or stream, and describe how native plants will be protected for their role as the foundation of healthy ecosystems, while nuisance non-native species will be controlled and recreational access will be provided. These plans are required by the Department of Natural Resources in order for them to permit aquatic plant harvesting programs under NR 109 Wis. Admin. Code.

The aquatic plant management plans below are the current plans for each waterbody, and were approved by the Dane County Lakes and Watershed Commission and Wisconsin Department of Natural Resources.

County Board of Supervisors Aquatic Plant Management Committee

Resolution 94, 2005-06, established an Aquatic Plant Management Committee of the County Board, charged with reviewing aquatic plant management options, including herbicides and mechanical harvesting, for invasive weed control, and overseeing preparation of aquatic plant management plans required by DNR to be in place before the 2007 harvesting season. The Committee began meeting in February 2006, and completed its work in October 2006. The Committee’s final report and appendices are available for download here.

Additional Aquatic Plant Resources



Yahara Waterways Trail Guide The Yahara Waterways Water Trail Guide is a great resource for exploring our area waters.