The Dane County Land & Water Resources Department manages an aquatic plant harvesting program for county waters. Harvesting follows permit requirements from the Wisconsin Department of Natural Resources (WDNR) and approved Aquatic Plant Management Plans for each waterbody. All harvesting of aquatic vegetation occurs in WDNR approved locations.
The county hires seasonal, limited-term employees to perform the harvesting. The supervised crews harvest aquatic plants from mid-May until mid-August using 11 mechanical harvesters and other harvesting equipment. The crews are guided by the our Water Resources Planner.
Adhering to DNR requirements, the county's policy is to cut and harvest Eurasian water milfoil and other invasives to help provide for reasonable recreational use of the lakes for boating, fishing and swimming, and lake level management, while preserving the health and balance of the lake ecosystem. Also, aquatic plant cutting in the Yahara River is performed for flood mitigation. Harvested plants are hauled by truck to remote compost sites.
Harvesting machines are cleaned to remove any invasive plants and animals before being moved from one body of water to another.
Plant harvesting for visual appeal and collection of plant pieces due to boat propeller action generally cannot be done due to the limits of equipment, staff, and budget.
The table below shows the number of harvesters that are currently out harvesting and where they are.
|Lake||Week of||# of Harvesters||Location|
|Waubesa||August 26, 2019||3|
|Yahara River||August 26, 2019||7||Waubesa to Kegonsa (6), Kegonsa to Stoughton (1)|
Dane County, in partnership with the City of Madison, City of Monona, and Friends of Lake Kegonsa Society, will have a shoreline barge crew working to pick up aquatic trash and debris from residents' piers on Lake Mendota, Lake Monona, and Lake Kegonsa through August. The pick-up will collect only aquatic vegetation and other debris that have washed up on shore. They will not pick up yard waste, brush or household waste. Vegetation must be placed on the pier by Monday at 7:00 am on the designated pick-up day. See schedule below for specific locations.
|Lake Mendota (week of)||Lake Monona (week of)||Lake Kegonsa (week of)|
|May 28||June 3||May 28|
|June 10||June 17|
|June 24||July 1||June 24|
|July 8||July 15|
|July 22||July 29||July 29|
|August 5||August 12|
|August 19||August 26||August 26|
Locations of these priority harvesting areas are indicated on each waterbody’s harvesting priority map. Harvesting is not prohibited in areas not marked on the maps. They are not, however, normally harvested due to very small rate of plant growth and budget limitations.
Priority #1 – Flood Mitigation (Keep Water Flowing Through the Yahara River)
This priority is assigned only to the Lower Yahara River between Lakes Waubesa and Kegonsa, where proactive harvesting is conducted to prevent high water issues, including possible flood conditions. Cutting and harvesting plants is generally confined to the deepest part of the river channel in order to maximize water flow downstream. Harvesting machine operators are also able to pick up large mats of floating plant fragments near the shoreline, which otherwise collect and rot around piers.
Priority #2 – Recreation and Navigational and Beach Access
To provide for recreation and navigational access, the harvesting machine operators usually cut and harvest a 30-foot strip parallel to shore, and 20-foot access lanes to open water. These cuts are normally 4 to 5 feet deep. The harvesting lanes are parallel to shore at a distance of 100 to 150 feet. This priority category includes harvesting done to provide access from private shorelines, public Lake Access Sites (boat landings), swimming beaches, and developed public shorelines.
Priority #3 –Shallow Cuts and Filamentous Algae Control
The Wisconsin DNR has approved a program on the Yahara River Chain of Lakes allowing for shallow cuts (2 to 3 feet deep from the surface) targeting specific invasive and nuisance plants. This provides better access for recreational activity. DNR is satisfied that the shallow cutting is not known to harm fish populations, and leaves the bottom part of the plant in place, which provides fish cover and stabilizes sediments. An aesthetic side benefit of these shallow cuts may be removing filamentous algal mats that are frequently found floating on top of the invasive and nuisance plants.
Priority #4 – Special Events
As time and budget permits, harvesting machine operators cut and harvest plants for special events held on or in the water. Only the smallest amount necessary for the event is cut. These priority areas are not mapped because locations vary.
Other – Deep Cuts
It has been shown that deep water cutting and harvesting of Eurasian Water Milfoil (EWM) close to the bottom reduces competition and releases native plants when present. Deep cuts have also shown to improve fish habitat and increase overall size and age structure of the fish within the water body. The deep cutting may provide for extended access for swimming, boating and fishing within these sites without repeated harvesting. On the limited occasions when this cutting and plant removal is provided, Dane County uses a special harvester with a 16-foot deep and 6-foot wide cutting head. The operation is labor-intensive, as it requires a first pass with a regular harvester (4 to 6 foot cut), a pass by the deep cutter, and another regular harvester pass to pick up plant fragments. Dane County staff are confident that most plant fragments are collected in this process.
Also shown on the harvesting priority maps are areas not cut for reasons as noted on the maps and listed below.
No-Cut Areas – Machinery Hazard
These are rocky or shallow areas where the harvesting equipment cannot operate due to potential damage to the equipment.
No-Cut Areas – Undeveloped Shoreline
These are undeveloped areas where access for motorized navigation is not needed. These undeveloped areas are identified to promote limited disturbance and promote vegetation growth. The areas are often consistent with the proposed Critical Habitat Areas from the aquatic plant management plans. They include important fish spawning and juvenile fish cover areas located outside of the typical harvesting lanes, where harvesting would reduce fish production.
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 and must be updated every five years. Some of the waterbodies also have a harvesting priority map that indicates potential cutting locations, as allowed by the permit.
Dane County staff and consultants surveyed aquatic plant communities during summer 2017 to learn how these plant communities have changed. They gathered data for each of approximately 7000 points on pre-determined sampling grids for the lakes being studied. At each point, they recorded information such as plant species present, water depth, sediment type, and fullness of the sampling rake. These survey results will helped us assess lake health and update some of our plans.
Dane County Land and Water Resources Department may provide services for the removal of aquatic plants in waters where there is an approved DNR Aquatic Plant Management Plan. Completed applications may be sent to the Dane County Land and Water Resources Department at 5201 Fen Oak Drive, Room 208, Madison WI 53718. For more information, please call 608-224-3730.
Most of the harvested aquatic plants are composted and available to the public at the county compost site located at 7102 Hwy 12 & 18, one-half mile east of I-90, across from Yahara Hills Golf Course. For larger amounts (one or more dump truck loads), please contact Dane County Lake Management at 608-246-3897.