Dane County Exec Parisi: Announces five phase project to improve water flow out of Yahara Lakes, mitigate flood risk

Contact: Ariana Vruwink
(608) 267-8823

Today, joined by County Board members and Department of Land and Water Resources staff, Dane County Executive Joe Parisi announced the County will remove sediment from a stretch of river between Lakes Monona and Waubesa that is restricting the flow of water through the Yahara Chain of Lakes. This location, one of six sites the County will target in five phases, is a $2 million initiative to improve water flow, flood storage capacity, and fish and wildlife habitat in the Yahara Lakes. This announcement comes after Dane County released a technical report to identify opportunities to address flooding on the Yahara Chain of Lakes and the County Board’s Lake Level Task Force submitted its final policy recommendations.

“With this initiative, Dane County will work to increase the flow of water through the Yahara Chain of Lakes and mitigate future flooding risk,” said County Executive Joe Parisi. “Climate change rains will continue to affect Dane County. That’s why it’s important we support initiatives like this one so our area can manage increasing volumes of storm water that come with being the fastest growing county in Wisconsin.”

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’s estimated that over 8.5 million pounds of sediment enters the Yahara River and Lakes each year from urban runoff.

Following last August’s heavy rains and widespread flooding, a Dane County technical work group began meeting to evaluate lake level conditions and model various scenarios to improve resiliency for future events. The group’s technical report found that removal of sediment produced a great benefit for lowering flood risks.

“I am pleased that the County Executive has identified locations to begin sediment removal as soon as possible,” said Michele Ritt, Chair of the Dane County Board’s Environment, Agriculture, and Natural Resources Committee. “This is great follow-up from the recommendations of the Yahara Chain of Lakes Lake Levels Task Force. Removing sediment and improving the flow of the water out of the system is a critical component of managing lake levels.”

The County’s multi-year sediment removal project in the Yahara Lakes will take place in five phases, with each phase carried out as Dane County secures permitting. The first phase, taking place between Lakes Monona and Waubesa, is expected to begin this year and the work will be bid this summer. At this site, the County is hoping to remove between two to three feet of sediment about 50 feet wide and approximately 1.75 miles long. This type of sediment removal is comparable to the County’s “Suck the Muck” initiative. Nearly a month after last August’s heavy rains, 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 Lakes in the wake of heavy rains.

In addition to this new $2 million initiative, Dane County included $440,000 in the 2019 budget for two new aquatic plant harvesters and $50,000 for a hydraulic crane that will mount to an existing barge to improve the county’s ability to remove aquatic plants, trees, and other large items of debris that restrict flow in the Yahara River. $50,000 in new dollars was included to staff this additional equipment, bringing the County’s total to thirteen harvesters and two barges that can help remove aquatic plants and debris that otherwise slow flow.

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