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Zebra Mussels Found in Brushy Creek, Blue Pit

  • 5/3/2016 1:13:00 PM
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The Iowa Department of Natural Resources (DNR) is watching Brushy Creek Lake after water samples collected last fall contained juvenile zebra mussels.

The DNR collects water samples and deploys settlement samplers in lakes across the state each summer to monitor for the invasive zebra mussel and will closely monitor Brushy Creek Lake this spring and summer to determine if it has an established population of zebra mussels.

“Finding zebra mussels veligers indicates to us that zebra mussels have been introduced into Brushy Creek,” said Kim Bogenschutz, the DNR’s Aquatic Invasive Species Program coordinator. “But, it’s too early to tell if there is an established population in the lake.”

The DNR has also confirmed that several zebra mussels were recently found in Blue Pit in Mason City. DNR staff will monitor Blue Pit this spring and summer to determine the abundance and distribution of zebra mussels.

The presence of zebra mussels in another lake highlights the spread of aquatic invasive species in Iowa waters. “The zebra mussels in Blue Pit probably arrived on or in a boat that had picked up the mussels from an infested water body, likely nearby Clear Lake or Bluebill Lake,” Bogenschutz said.

Zebra mussels look like small, D-shaped clams that have alternating light and dark bands. Most are less than one inch long. They are filter feeders that can form dense clusters as they attach to hard underwater surfaces.  In the case of large infestations, they may interfere with aquatic food chains, kill native mussels, clog water intakes, increase algae blooms, and cover beaches with dead shells.  Currently there is no effective treatment to control zebra mussels once they have infested a lake. 

Zebra mussels are native to the Caspian Sea region of Asia and were introduced into the Great Lakes in the 1980s from ballast water of oceangoing ships. They have spread throughout lakes and rivers in the Midwest and around the country.  Known populations within Iowa include Clear Lake, Bluebill Lake, the Okoboji chain of lakes and the Mississippi River.

Young zebra mussels are microscopic and can be unintentionally transported with water in bilges, live wells or bait buckets.  Adult zebra mussels can attach to boats, trailers and aquatic vegetation.

It is illegal to possess or transport prohibited aquatic invasive species, such as zebra mussels, in Iowa. Boaters must also drain all water from boats and equipment before leaving a water access and must keep drain plugs removed or opened during transport.

“Boaters and anglers can unintentionally spread zebra mussels and other aquatic invasive species if they do not take the proper precautions - clean, drain, dry - after each time out on the water,” said Kim Bogenschutz, the DNR’s Aquatic Invasive Species Program Coordinator.

  • CLEAN any plants, animals or mud from boat and equipment before leaving a water body.
  • DRAIN water from all equipment (motor, live well, bilge, transom well, bait bucket) before leaving a water body.
  • DRY anything that comes into contact with water (boats, trailers, equipment, boots, clothing, dogs). Before transporting to another waterbody either:

Spray your boat and trailer with hot, high-pressure water; or

Dry your boat and equipment for at least 5 days.

  • Never release plants, fish or animals into a water body unless they came out of that water body and empty unwanted bait in the trash.


More information about aquatic invasive species and a list of infested waters can be found in the 2016 Iowa Fishing Regulations booklet.

If you see a zebra mussel, please note its location and contact your local fisheries office or the Aquatic Invasive Species Program in Boone.