Dane County Office of Lakes & Watersheds
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Lake Management

Weed Harvesting

Aquatic weeds are harvested by the Dane County Public Works Department. The county's basic policy is to cut or harvest aquatic weeds whenever it will enhance the overall recreational or aesthetic value of the lakes. The priority as to where cutting occurs depends on the timing of weed growth and where the cutting will do the most good. Weeds in the Vilas and Tenney park lagoons are usually cut first. Cutting is done next on Lakes Monona or Waubesa, whichever has more weeds. Lakes Monona or Waubesa, whichever has more weeds. Lakes Mendota and Kegonsa are usually cut last, and there have been years when weeds have not been harvested on either lake.

When weeds are cut along the shoreline, boat landings and swimming beaches receive special attention. When weeds are particularly heavy, paths are cut along the residential shoreline and out to the lake. The channel between Lakes Monona and Waubesa is cut to allow for boat passage. The river from Lake Waubesa to Lake Kegonsa is also cut to maintain flow. If weeds are not cut in the river, it is not possible to discharge the volume of water needed to keep the lakes from exceeding summer maximum lake levels.

Special events, such as the water ski show in Monona Bay, the Milk Carton Regatta at Vilas Park, the triathlon at Warner Bay, and the Badger Sports Festival, receive priority for weed cutting.

Large weed beds in Turville Bay, University Bay, Warner Bay, etc., are not cut. If time and money would permit, paths could be cut through these weed beds for fishing. Vilas and Tenney parks are cut once again in the fall so that weeds will not freeze in the ice.

Chemical Control

It is illegal for individuals to chemically treat shoreline areas without a permit from the Department of Natural Resources (DNR). Health hazards may occur to people and wildlife when chemicals are applied carelessly. (Simply because a chemical can be sold does not mean it is harmless.) Thus, non-chemical methods to control plants should be explored first by contacting the aquatic plant specialists in the DNR.

Chemicals, such as copper sulfate and sodium arsenite, have been heavily used in the past for algae and weed control, and there are now questions whether these elements may have accumulated in bottom sediments to levels that may be of environmental concern. Sediment sampling is being done to assess potential problems. Use of chemicals for weed and algae control is presently limited to small areas, mainly for weed control along private shorelines, and is generally conducted under the supervision of DNR.

Lake Levels

DNR has established minimum and maximum lake levels for the Yahara lakes. The Dane County Public Works Department checks and regulates the lake levels by making appropriate outflow adjustments. There is only a six-inch difference allowed between summer minimum and maximum levels, and it is very difficult to maintain lake levels within this range. Lake levels are lowered for the winter to prevent shoreline ice damage, especially on Lake Mendota, and to store spring runoff from the watershed.

Water and Shoreline Regulations

All navigable waters in Wisconsin are held in trust by the state for the public. Many activities affecting navigable waters and shorelines require permits or approvals from the DNR. Some of the physical alterations to navigable waters that require permits include: channel changes, riprap, structures, grading, pipelines, sand blankets for improving beach conditions, private bridges, dams, dredging and surplus water diversion. Permits also may be needed from the U.S. Army Corps of Engineers for filling wetland areas. Generally, no permit is required for pier construction unless the pier extends beyond a pierhead line or interferes with the rights of the public or other riparian proprietors.

Local units of government also administer regulations to control development along the shorelands of lakes and streams and within floodplains. Shoreland control is confined to lands within 1000 feet of a navigable lake, pond or flowage, or within 300 feet of a river or navigable stream (or to the landward side of the floodplain). Shoreland, wetland and floodplain zoning ordinances often include: restrictions on filling or dredging in wetland and floodplain areas; permitted use of shorelands, floodplains and wetlands; lot size; setbacks of buildings from navigable waters; tree and shrub cutting along shorelands; and location and size of waste disposal systems. County and municipal zoning administrators should be contacted when activities are being contemplated in these areas.

Fish Management

The Yahara lakes have a diverse and productive fishery. The value of the fishery in numbers is striking. More than 246,000 fishing trips have been projected annually on Lakes Mendota, Monona, Waubesa and Kegonsa, with anglers harvesting more than one million fish.

Lake Mendota is one of Wisconsin's most popular fishing lakes. Generally, fishing for perch and other panfish is outstanding both in the summer and in the winter. Large- and smallmouth bass, northern pike, walleyes and recently stocked hybrid muskies are present, as well as a cisco population that has been increasing after a decline that began over 40 years ago. Panfish are also abundant in Lake Monona. Thirty-six species of fish have been found in this lake, including walleye, muskie, northern pike, largemouth bass, bluegills and sturgeon. Lake Waubesa also supports a productive warn water fishery dominated by panfish, but includes northern pike, largemouth base and some walleye. Fish commonly caught in Lake Kegonsa are crappies, walleye, largemouth bass, bluegills and perch. Stunted panfish, especially bluegills, dominate Lake Wingra, although muskies have been stocked and some largemouth bass are present. All the lakes contain rough fish, such as carp and freshwater drum, that have caused problems by stirring up bottom sediments.

DNR is responsible for managing the fishery of the Yahara lakes. A major fish and lake management experiment is being implemented on Lake Mendota by the DNR and the University of Wisconsin. The project, known as "biomanipulation" involves altering the food chain of the lake. A large number of predator fish, such as northern pike and walleye, are being stocked in the lake. It is hoped they will eat and reduce panfish populations, which could correspondingly increase the number of zooplankton (microscopic organisms) that the panfish devour. Zooplankton eat algae and if zooplankton populations increase, the amount of algae may decrease. Thus, water clarity could improve, in addition to the sport fishery.

DNR also manages rough fish control and harvesting on the lakes. Dane County is participating by promoting and subsidizing additional harvesting of carp and other rough fish. This not only benefits the fishery but also helps water quality, since carp stir up bottom sediments and recirculate nutrients.

Fish Testing and Health Advisories

Throughout the year, scientists from the DNR collect fish from hundreds of lakes in the state and test them for toxic chemical contamination. Each spring and fall, they issue a health advisory that explains which sport fish exceed health standards and where they were collected. Lake Monona was put on the health advisory list in April 1987 after DNR experts confirmed that walleyes larger than 22 inches contained more than 0.75 parts per million (ppm) of mercury. The allowable limit for mercury is 0.50 ppm. At the concentrations found, pregnant or breast-feeding women, women who plan to have children, and children under 15 should not eat walleyes 22 inches or larger. Everyone else should limit their intake to no more than one meal per month. So far, no other fish in the Yahara lakes have been found to contain enough mercury or any other chemical to warrant a health advisory.

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