Zebra Mussels Confirmed in West Branch Lakes

Zebra mussel (Dreissena polymorpha)


The Forest Preserve District of DuPage County confirmed the presence of invasive, nonnative zebra mussels in Deep Quarry Lake and Bass Lake at West Branch Forest Preserve in Bartlett. 

The Forest Preserve District is currently working with the Illinois Department of Natural Resources and the Illinois Environmental Protection Agency to prevent any further spread. Because Deep Quarry Lake and Bass Lake flow into the West Branch of the DuPage River, the District placed zebra mussel monitoring stations along the river as well as in other forest preserve lakes. The District’s aquatic invasive species monitoring and education program, including the Protect Your Waters volunteer program, monitors waterways for zebra mussels and seeks to educate preserve visitors about preventing the spread of aquatic invasive species.

Boaters with valid District private-boating permits can still use their watercraft on Mallard Lake at Mallard Lake Forest Preserve in Hanover Park, Silver Lake at Blackwell Forest Preserve in Warrenville and Round Meadow Lake at Hidden Lake Forest Preserve in Glen Ellyn.


The zebra mussel (Dreissena polymorpha) is a fingernail-sized, striped nonnative mollusk. It has spread across the United States by attaching to watercraft and the inside of bait buckets.

Zebra mussels are prolific breeders. They can critically harm native mussel populations by interfering with feeding. Large populations can filter all of the water in a lake in one day, consuming plankton that native species rely on for food. Some native waterfowl and fish feed on zebra mussels but do not consume enough individuals to control populations.

Invasive zebra mussels have been found in Deep Quarry and Bass lakes.

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