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County Executive's Office

Dane County Unveils New Technology to Keep Beaches Safe and Healthy

July 08, 2020
Ariana Vruwink, 608-267-8823
County Executive

Today, County Executive Joe Parisi joined Dane County Land and Water Resource Department staff at Mendota County Park to unveil new technology that is being tested to vacuum out hazardous blue-green algae blooms near local beaches to keep them safe and healthy. This cleaning system is being used to remove algae and decaying plants that emerge along the shoreline at Mendota County Park, which can increase in frequency during hot weather patterns like Dane County is currently experiencing. With the new system in place, water quality around the beach will be improved for safe swimming through this summer and beyond.

“As the summer heats up and the COVID-19 pandemic continues, Dane County residents are turning to our lakes to cool down and reconnect with the outdoors,” said Dane County Executive Joe Parisi. “This new technology will allow families to have a safe and fun time at the beach, without having to worry about water quality. Projects like this are an extension of our equity work – providing safe, free fun across our community and encouraging kids to get outside.”

The county’s vacuum technology will remove algal scum, filamentous algae, floating aquatic plants, and trash from the water. The system consists of a vacuum intake nozzle attached to piping that uses a venturi pump design to create a suction force at the nozzle intake. The suction created at the intake pulls water and algae scum at the surface, which discharge into filter bags where clean water flows back into the lake and the algae and decaying plants will remain trapped inside.

Excessive blooms of algae commonly occur during the summer months in the Yahara Lakes. Such blooms can be a health concern to humans and pets. Some species of blue-green algae float on the water’s surface when winds are relatively calm. These moderate winds then push the buoyant algae to downwind shorelines where it can pile up as thick mats or scums along with other floating debris such as aquatic plants, detached filamentous algae, dead fish, and trash.

Public beaches on the Yahara lakes are particularly susceptible to trapping material because of the shoreline geometry with cutouts into riprap banks. The floating algae debris can break up or move elsewhere when wind conditions change. Otherwise, the trapped debris remains until it decomposes. While local municipality staff remove cut weeds and debris from beaches, blue-green algal scums, due to their watery nature, can only be removed with specialized pumping equipment. County Executive Parisi included $20,000 for this algae vacuum initiative in his 2018 budget.

In addition to cleaning algae on area lakes, Dane County has expanded its “blue waters barge” program to include Lake Waubesa.  Previously, the program included lakes Mendota, Monona, and Kegonsa.  The “blue waters barge” program began in 2008, when Dane County partnered with the City of Madison to clean up lakes Mendota and Monona by removing aquatic plants and debris on piers, stormwater outlets, and beaches. The partnership enables Dane County to provide a means for disposal and the City of Madison, Town of Westport, City of Monona, and Friends of Lake Kegonsa to cover barge crew costs. New this year, a similar cost sharing partnership is now in place with the Lake Waubesa Conservation Association for Lake Waubesa and Town of Westport for Lake Mendota.