Sediment removal

Dredgit Corp. will be awarded the contract to begin the first phase of Dane County’s Yahara Chain of Lakes sediment removal project. This first phase will take place between lakes Monona and Waubesa.

Dredgit Corp. will be awarded the contract to begin the first phase of Dane County’s Yahara Chain of Lakes sediment removal project. This first phase will take place between lakes Monona and Waubesa. The contract totals about $3.25 million and will further the county’s initiative to improve water flow, flood storage capacity, and fish and wildlife habitat in the Yahara Lakes.

“As climate change rains continue to impact our area, Dane County is committed to mitigating future flooding risks and increasing the flow of water through the Yahara Chain of Lakes,” Dane County Executive Joe Parisi said. “We are excited to award this contract and work on this project in 2020. In the new year, we will also begin to form our own sediment removal crew to accelerate future phases of this initiative.”

The county’s multiyear sediment removal project in the Yahara Chain of Lakes will take place in five phases, with each phase carried out as Dane County secures permitting. At the site of this first phase, the county hopes to remove between 2-3 feet of sediment about 50 feet wide and about 1.5 miles long.

Water currently comes into the Yahara Chain of Lakes faster than it goes out – taking 2 inches of rain more than two weeks to leave the chain of lakes. The efficient movement of water downstream can be undermined by sediment loading. While sediment movement is a naturally occurring process, accumulation of sediment in the Yahara River and Chain of Lakes is increased by human activity, including urban development. It is estimated that more than 8.5 million pounds of sediment enter the Yahara River and Chain of Lakes each year from urban runoff.

The type of sediment removal that will take place between lakes Monona and Waubesa is comparable to the county’s “Suck the Muck” initiative. Nearly a month after historic rainfall in the late summer of 2018, water levels on Lake Monona were 8 inches higher than Lake Waubesa. Sediment removal in this location could improve water quality, habitat, navigation and the rate at which water leaves the Yahara Chain of Lakes in the wake of heavy rains, officials said.

In addition to this investment, Parisi is also including money in his 2020 budget to create a new sediment removal crew and purchase the equipment needed for the county to do its own hydraulic sediment removal.

The 2020 budget includes $5 million to purchase equipment needed for sediment removal work and the staff to carry out the job.

Permits have been secured, and the project is expected to start in the spring.

(1) comment

pat rossman

We are wondering why The first phase starts at the north end of the chain rather than the south? It would seem more water flowing will cause much flooding from waubesa through kegonsa

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