Posted on May 17, 2023
Dredging efforts aimed at removing urban runoff from the Yahara chain of lakes in Dane County will resume this year at two separate locations, county officials said Tuesday.
The multi-phase project is designed to improve water flow in the larger water system to reduce the risk of flooding. This year, crews will work to remove sediment in the areas from Lake Waubesa to Lower Mud Lake — Phase 2A — and Lake Kegonsa to County Highway B — Phase 2B/2C.
During a news conference Tuesday morning, County Executive Joe Parisi said the buildup of urban runoff — primarily fine sand used in construction projects and to treat roads in the winter — is impeding the flow of water through the Yahara River watershed.
Water taking longer to drain through the system could make future flooding events worse, he added.
“If we think back to 2018 when we had the flooding and the almost unprecedented rains, what we saw during those floods was more water coming into the system than the lakes were able to empty out, hence backing up and flooding,” he said, “and we know that we’re going to be seeing more of those types of rain events as our climate changes.”
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.
The project began in 2020, two years after the 2018 floods, with efforts focused on the area between lakes Monona and Waubesa. By the time that phase — Phase 1 — was complete in 2021, crews had removed roughly 40,000 cubic yards of sediment from the watershed, Parisi said.
As part of Phase 2A, county officials expect to remove another 19,000 cubic yards of sediment between Lake Waubesa and Lower Mud Lake this year. Phase 2B/2C is expected to result in 100,000 cubic yards of sediment being removed south of Lake Kegonsa.
Phase 3, meanwhile, is expected to begin next year between Lower Mud Lake and Lake Kegonsa.
The dredging efforts are separate from the Suck the Muck initiative, which focuses on removing significant buildups of agricultural runoff.