Dane County Debuts New Dredging Equipment, Will Accelerate Efforts to Improve Water Flow & Flood Storage Capacity in Yahara Lakes

March 22, 2021
Ariana Vruwink, 608-267-8823
County Executive, Land & Water Resources

Today, Dane County Executive Joe Parisi joined Land and Water Resources Department staff to debut new hydraulic dredging equipment the County will use to improve water flow, flood storage capacity, and fish and wildlife habitat along the Yahara Chain of Lakes. This equipment acquisition is the latest step Dane County has taken in its multi-year sediment removal initiative to help the Yahara Lakes better handle heavy rains and reduce the risk of lake flooding. The hydraulic dredge will be deployed this summer as part of the second phase of Dane County’s Yahara Chain of Lakes Sediment Removal Project, which will focus on areas downstream of Lakes Waubesa and Kegonsa.

“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,” said Dane County Executive Joe Parisi. “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.”

Currently, water comes into the Yahara Chain of Lakes faster than it goes out—taking two inches of rain over two weeks to leave the Yahara Lakes system. 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 Lakes is greatly increased by human activity, including urban development. It is estimated that over 8.5 million pounds of sediment enter the Yahara River and Lakes each year from urban runoff.

Dane County’s sediment removal project in the Yahara Lakes system will take place in five phases, with each phase carried out as Dane County secures permitting. In May 2020, Dane County kicked off the first phase of the project between Lakes Monona and Waubesa. The County removed approximately 40,000 cubic yards—or more than 3,000 dump truck loads—of sediment before the $3.25 million effort concluded last fall.

While Dane County has been fortunate to avoid sustained high water events on area lakes more recently, staff are moving forward expeditiously to keep the project going, given the unpredictability of climate change rains. The second phase of the initiative will kick off in the coming months and will focus on two stretches of the Yahara River: Lake Waubesa to Lower Mud Lake and Lake Kegonsa to Highway B.

Parisi included $5 million in his 2020 budget to purchase this new equipment and create four staff positions to carry out the job. Booster pumps for the dredging work were received in October 2020. The dredge itself was received near the end of February. Parisi included an additional $2.5 million in his 2021 budget to keep the initiative on track this year.