Floating weed harvesters have opened passages through Dane County’s dense tangles of underwater plants for about 50 years.
The barges wield rotating cutting bars like those on farm combines to cut a submerged crop that is fertilized too well by runoff of nutrients like dairy manure.
Each spring, the county launches a flotilla of 10 paddle-propelled aquatic mowers to cut and remove thousands of tons of soggy vegetation to improve navigation and reduce flood risk.
Most years, Lake Monona gets the most attention and produces the biggest bounty among the six to 16 bodies of water that may be targeted in a given season.
But the fleet’s top priority is a wooded, relatively untraveled stretch of the Yahara River that flows from Lake Waubesa to Lake Kegonsa. If a channel isn’t regularly buzzed through the riverbed’s mane of wild celery, the waterway can become a bottleneck that increases the flood risk upstream.
In addition to the river and lakes Monona, Mendota, Waubesa, Kegonsa and Wingra, crews may also cut Upper Mud, Fish, Indian and Stewart lakes; Lake Belle View; lagoons in Tenney, Vilas and Warner parks; a quarry in Verona; and ponds in the Jenni and Kyle Preserve in Fitchburg.
The steel harvesters usually mow 30-foot-wide strips parallel to shore and 20-foot-wide lanes to open water.
The county could remove more weeds, but that would rob fish of habitat and allow sediment to cloud the water.
Most of the wet bounty is composted and available to the public at 7102 Highway 12-18, a half-mile east of I-90.
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