Dane Co. purchases hydraulic dredging equipment for sediment removal from Yahara River, connected lakes

MADISON, Wis. –Dane County leaders unveiled Monday new hydraulic dredging equipment the county will use in the coming years to help excess water drain more quickly from nearby lakes and rivers.

Dane County Executive Joe Parisi and Land and Water Resources Department staff deputed the dredging equipment during a noon press conference. The equipment will be used to improve the overall flow, flood storage capacity and wildlife habitats along the Yahara River and connected lakes.

“This equipment will accelerate our work to pass water through the Yahara Chain of Lakes at a steadier clip and help mitigate the risk of flooding,” Parisi said. “By owning and operating our own equipment, we can ensure for years to come that Dane County has the tools and expertise in-house to manage work demands created by the new realities of climate change and rapid urban development.”

As of now, water comes into the Yahara Chain of lakes faster than it drains. County leaders said it takes two inches of rain more than two weeks to leave the system. That, Parisi said, is often caused by sediment buildup.

While sediment movement and buildup is a naturally occurring process, it is accelerated in the Yahara River and connected lakes because of human activity, including urban development. An estimated 8.5 million pounds of sediment enter the local waterways each year due to urban runoff.

The dredge will be deployed this summer to remove sediment from the waterways, specifically focusing on areas downstream from lakes Waubesa and Kegonsa. The planned efforts this summer will kick off the second phase of Dane County’s sediment removal project.

Last year, as part of the first phase of the project, the county removed roughly 40,000 cubic yards — more than 3,000 dump truck loads — of sediment from the area between lakes Monona and Waubesa.

The equipment was bought in 2020 using $5 million from Dane County’s budget. Parisi included $2.5 million in his 2021 budget to continue the ongoing initiative.