It's the Law

Aquatic Invasive Species

Introducing non-native species into Wisconsin waters can upset the balance of the ecosystem, thereby harming the environment. Aquatic invasive species, such as zebra mussels, quagga mussels, milfoil, and hydrilla, are often spread between waterways by hitching a ride on vessels and trailers. When transplanted into new waters, these organisms proliferate, displacing native species and damaging the water resource.

To help prevent spreading aquatic nuisance species, Wisconsin law requires that you:

  • Inspect your vessel, trailer, and equipment, and remove any attached plants and animals before launching and before leaving the area and traveling on a public highway.
  • Drain all water from all boats, motors, trailers, boat equipment, and fishing equipment before you transport the boat, trailer, or equipment away from that body of water or its shore.
  • Drain all water from any boat being transported over land before the boat enters Wisconsin from another state.

When you leave a body of water that contains aquatic invasive species, you also should disinfect everything by:

  • Rinsing your vessel, propeller, trailer, and equipment with hot water (at least 104° Fahrenheit), or…
  • Air-drying your vessel and equipment for at least five days.

Rules for Transporting Live Minnows and Other Fish: To prevent the spread of Viral Hemorrhagic Septicemia (VHS), a deadly fish virus that is threatening Wisconsin’s fish, the Wisconsin DNR has established certain rules.

  • If obtained from a Wisconsin bait dealer, live minnows may be transported away and used again:
    • On the same water, or…
    • On any other waters if no lake water, river water,or other fish were added to the container.
  • You may not transport any other live fish or any live fish eggs away from any state waters.
  • For more information, visit

If you think you have found an aquatic invasive species, save it and contact your nearest Wisconsin Department of Natural Resources office.

For more information on aquatic nuisance species found in Wisconsin, visit