County dredging - Lake Kegonsa 2018

Lake Kegonsa, shown here with high water in summer 2018, is part of the chain of lakes that the county will be dredging this year. Water has been flowing into the lakes faster than it can drain out during rain events.

Dane County is one step closer to starting a massive dredging project aiming to help improve water flow and wildlife habitat on the Yahara Chain of Lakes.

Dredgit Corporation will be awarded a contract worth around $3.25 million to begin the first phase of Dane County’s Yahara Chain of Lakes Sediment Removal Project, the county announced in a Dec. 30 news release. It’s the first phase in the multi-year project to improve water flow, flood storage capacity, and fish and wildlife habitat, and it’s planned for this spring between lakes Monona and Waubesa.

Lake Kegonsa, just north of Stoughton, is downstream of those two lakes, and drains through the Yahara River in the city.

While specific project timelines are still being prepared, County Executive Joe Parisi wrote that work will this year will also include forming a sediment removal crew to “accelerate” future phases.

“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,” he said in the news release.

The multi-year sediment removal project is planned in five phases, with each carried out as the county secures permitting.

County officials hope to remove between two and three feet of sediment about 50 feet wide and 1.5 miles long during the first phase. Sediment removal in this location could improve water quality, habitat, navigation and the rate at which water leaves the Yahara Lakes in the wake of heavy rains, according to the news release.

The dredging effort is an attempt to change the flow of water moving through the lakes, which comes in faster than it goes out, meaning two inches of rain takes more than two weeks to leave the system, according to the news release. At least 8.5 million pounds of sediment are estimated to enter the Yahara River and lakes each year from urban runoff.

Email Unified Newspaper Group reporter Scott De Laruelle at scott.delaruelle@wcinet.com.