Tuesday, Dane County Executive Joe Parisi announced a multi-million dollar project to clean up the Yahara river. The plan would deepen the river by at least two feet and reduce the risk of flooding. To help prevent intense flooding like the county saw in summer of 2018, a project from the Dane County Land and Water Resources Department will suck the muck.
That means it’ll take the sediment at the bottom of the Yahara River so water is able to flow more freely through a chain of four lakes: Mendota, Monona, Waubesa and Kegonsa.
Dane County Land and Water Resources Department Assistant Director John Reimer, who is involved in the project, watches the flow of the system. Currently water is entering the watershed faster than it is flowing through. If this continues, the Yahara River and chain of lakes could flood.
“When we look at water levels here from a management perspective, we look at the flows,” he explains. “We look at how much water comes in, and how much water leaves and in the end that will determine the water levels.”
The county is using hydraulic dredging, which works like a big vacuum. It sucks up the sediment holding up the flow of water and empties it to a settlement pond. This year, the project is focusing on the section of river between Lakes Monona and Waubesa. Reimer says the county has purchased its own dredging barge and equipment and will hire a team of about five people for the second phase.
Phase one, which will conclude this year, will remove over three thousand dump trucks worth of sediment. A map of the phases can be found on the county website.
Another part of Dane County’s “Suck the Muck” project removes phosphorus from river and stream beds that feed into area lakes. Dane County Executive Joe Parisi is allocating over 9 million dollars to continue the project in 2021.
The City of Madison is also working to address the potential of flooding by studying Madison’s watersheds and flooding damage from August 2018. City Engineer Spokesperson Hannah Mohelnitzky says during that time the isthmus experienced both flash flooding and lake flooding.
“Because that area is so low, and it’s been developed over time and design standards have chanced for the storm-water system, the soil has been saturated multiple times over the years, that what makes it so susceptible to flash flooding,” Mohelnitzky says.
The city engineers survey other Madison watersheds, and are holding a virtual public information meeting tonight for residents in the Greentree/McKenna watershed.
Featured image from City of Madison Engineering East Isthmus and Yahara River Watershed Study project.
