Native vs. Invasive Lake Plants in Wisconsin
As of September 2026: This page summarizes the native/invasive distinction under Wis. Admin. Code NR 40 and NR 109. Confirm any specific plant with your regional APM coordinator.
Every removal rule on this site traces back to one question: is the plant native or invasive? Wisconsin doesn't regulate aquatic vegetation by how annoying it is to a swimmer or how it looks around a dock. It regulates by origin, and that single distinction decides whether you need a permit, how wide an area you can clear, and which tools are on the table.
What makes a plant "invasive" in Wisconsin
Wisconsin's invasive species rule, NR 40, classifies certain non-native species as restricted or prohibited because they spread aggressively, outcompete native vegetation, and change lake ecosystems in ways that are hard to reverse. Eurasian watermilfoil, curly-leaf pondweed, and starry stonewort are the three most common examples on Wisconsin lakes. None of them evolved here, and all three can take over a shoreline within a few growing seasons if left unchecked.
What makes a plant "native"
Native plants, coontail, chara, native watermilfoil, white water lily, spatterdock, and dozens of others, evolved as part of Wisconsin's lake ecosystems. They provide fish habitat, filter nutrients, stabilize sediment, and generally keep a lake healthier than a lake with no vegetation at all. A lake completely cleared of native plants usually has worse water quality, not better, which is the core reason the DNR protects them.
Why the removal rules split this way
The state wants invasive species gone and native species to stay, so the rules under NR 109 reflect that goal directly.
| Removal method | Invasive species | Native species |
|---|---|---|
| Hand-pulling | Exempt statewide, any width | Exempt only within a 30-ft corridor |
| Mechanical harvesting | Needs a permit | Needs a permit |
| Herbicide | Needs a permit (NR 107), every season | Needs a permit (NR 107), every season |
| Small waterbody exemption | Applies if 10 acres or smaller, on your land | Applies if 10 acres or smaller, on your land |
The gap only shows up at the hand-removal row. Beyond that, chemical and mechanical methods are regulated the same way regardless of what's growing, because both methods can affect water quality and habitat broadly, not just the target plant.
Why misidentification is a real risk
Because the rule hinges on identification, and several invasive species have close native lookalikes, getting the plant wrong has real consequences. Eurasian watermilfoil and native watermilfoil differ mainly by leaflet count. Coontail is often mistaken for milfoil at a glance. Chara and starry stonewort both feel gritty and smell musty, but only one of them is regulated as invasive. Removing a native plant while believing it's invasive doesn't change which rule applies to it.
See the full identification set on the identification page, or the individual guides for Eurasian watermilfoil, coontail, and chara.
When in doubt
If you can't confirm what you're looking at, treat it as native until you know otherwise, and keep any removal inside your 30-foot corridor. For a step-by-step walkthrough of that exemption, see manual removal without a permit, and for the full permit decision tree, see the DNR permit rules page.