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Dane County Kicks Off New Season of Climate Change Mitigation Project to Reduce Yahara Lakes Flooding Risk

May 16, 2023
Ariana Vruwink, 608-267-8823
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Today, County Executive Joe Parisi joined Land & Water Resources Department staff at the Babcock County Park boat launch to kick-off a new season of Dane County’s five-phase Yahara Chain of Lakes Sediment Removal Project. Crews will work at two separate locations this year—Lake Waubesa to Lower Mud Lake (Phase 2A) and Lake Kegonsa to Highway B (Phase 2B/2C). To date, approximately 33,000 cubic yards of sediment has been removed from the Phase 2 sites to help improve water flow, flood storage capacity, and fish and wildlife habitat in the Yahara Lakes.

“With the unpredictability of climate change rains, it’s important for the Dane County community to take a proactive approach and remain resilient,” Parisi said. “Through our Yahara Chain of Lakes Sediment Removal Project, we’re working to help mitigate future flooding risks by increasing the flow of water through the lakes and improving the management of lake levels during high water periods. We’re excited to continue this work in 2023.”

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.

The 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 in 2021.

Between Lake Waubesa and Lower Mud Lake (Phase 2A), Dane County is using its “Dragon Dredge,” first unveiled in 2021, to move water through the Yahara Chain of Lakes at a steadier clip and help mitigate the risk of flooding. Parisi included $5 million in his 2020 budget to purchase this new equipment and create four staff positions to carry out the job. By owning and operating its own equipment, Dane County can ensure for years to come that it has the tools and expertise in-house to manage work demands created by the new realities of climate change and rapid urban development.

An additional 19,000 cubic yards of sediment is expected to be removed from Phase 2A this year, when it will also reach completion. The work for Phase 2B/2C started in summer of 2022. A dewatering basin was built to store sediment hydraulically dredged from the Yahara River.  The hydraulic dredging is anticipated to start in spring of 2023. Phase 2B/2C will remove approximately 100,000 cubic yards of sediment and is being carried out through Michels Construction, a private contractor.

Phase 3 is located between Lower Mud Lake and Lake Kegonsa. Planning and Engineering drawings have begun, as well as permitting and preliminary site work for construction of the dewatering basin. Sediment removal for Phase 3 is anticipated to begin in spring of 2024 and will removal approximately 60,000 cubic yards.

Parisi’s capital budget allocated $3 million for the Yahara Chain of Lakes Sediment Removal Project to continue in 2023. Parisi also added two more fulltime dredging positions to ensure Dane County has the bodies necessary to continue prioritizing this work.

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