NR 40: The Invasive Species Rule

The “Invasive Species Identification, Classification, and Control Rule,” or NR 40, classifies and regulates aquatic invasive threats.



How does this work and what does this mean? 


There are two classifications under this regulation, each with slightly different rules:

Prohibited and Restricted species.


These are species not yet in Wisconsin, or only in limited areas. They are likely to cause impacts, but management and prevention is possible. Transportation, possession, transfer, and introduction are banned.

Example (pictured): Yellow floating heart


These species have already spread widely throughout the state. Impacts are evident and complete eradication is unlikely. Transportation, transfer, and introduction are banned; possession is allowed except for fish and crayfish.

Example (pictured): Eurasian watermilfoil

Steps for Prevention


  • INSPECT your equipment for invasives
  • REMOVE all attached debris
  • DRAIN water from boats & equipment
  • NEVER MOVE live fish away from a water body
  • BUY MINNOWS from a WI bait dealer. Use leftover minnows only under certain conditions.*

*You may take leftover minnows away from any state water and use them again on that same water. You may use leftover minnows on other waters only if no lake or river water, or other fish, were added to their container.


  • NEVER TRANSPLANT water garden plants or release crayfish, fish or other animals into ANY waterways.
  • DO NOT PURCHASE prohibited or restricted species. Whenever possible, purchase native plants and animals.
  • CHECK YOUR PLANT ORDERS for potentially invasive “hitchhikers.”
  • BE AWARE of NR 40 regulations.
  • PROPERLY DISPOSE of unwanted garden or pond plants and animals.

Nursery owners: Do not purchase or sell invasive plants or animals that are restricted or prohibited in Wisconsin.

Learn More

Join River Alliance, our members, and partners as we work to promote responsible water recreation across the state and help Stop Aquatic Hitchhikers.

To learn more about NR 40 regulations and how you can help, please visit: