Roesiger Invasive Aquatic Plant Control

The Problem - Invasive Aquatic Plants

Lake Roesiger is home to an abundance of native plants. These beneficial plants are vital to keeping lakes healthy. They provide important food and habitat for aquatic life including fish, turtles, frogs waterfowl and other aquatic life. They also are important for us as they help to clean the lake by filtering pollution and prevent shoreline erosion. 

Unfortunately, Lake Roesiger is also home to a few non-native, invasive plants. These plants can crowd out the beneficial native plants, harm lake ecology, and interfere with swimming, fishing and boating. So while it is important to keep native plants in the lake, it can be desirable to manage invasive plants to reduce their impacts. 

The lake has three invasive species of concern in the lake basin - Eurasian watermilfoil, fragrant waterlily and narrow-leaved arrowhead. There are also three invasive species found on the lake shoreline - yellow flag iris, purple loosestrife and Japanese knotweed. See our interactive plant map to view the locations of native and invasive aquatic plants in Lake Roesiger. To learn more about the different types of aquatic plants and how to identify them visit our aquatic plants webpage


Fragrant Waterlily Patch and Flower

Fragrant waterlily

Introduced as an ornamental plant, it takes over shallow areas, limiting habitat and boating and speeds causes the lake to fill in faster.

Eurasian watermilfoil

Noxious weed, grows in hard to swim through mats and crowds out native plants. Can reduce oxygen in the water. Easily regrows from broken fragments.

Eurasian Watermilfoil Patch and Flower

Grass-Leaved Arrowhead

 Less researched, may displace natives plants and wildlife, can be a nuisance to swimmers. Found only in 5 lakes in the state, including Lake Roesiger.

Grass-leaved Arrowhead Patch and Flower

Yellow Flag Iris

Grows in dense clumps in shallow waters of lakes and streams. A piece of root can break off and grow a new plant. Resin from it can irritate the skin.  

Yellow Flag Iris Patch and Flower

Purple Loosestrife

Emerges from the water in dense stands, spreads rapidly. Crowds out plants that make for good nesting habitat. Could be mistaken for spiraea or fireweed 

Purple Loosestrife Patch and Flower