Floating Islands Provide Habitat

in the Milwaukee River

Floating islands along the industrialized corridor of the Milwaukee River have provided fish, such as smallmouth bass and green-eared sunfish, habitat and a way to navigate upstream.


A project along the Milwaukee River aims to increase success of fish spawning by providing habitat. The sides of wild streams are often gently sloping with plenty of plant cover for small fish to rest and feed in. Steel bulkheads that line rivers in urban areas are void of plant life, and provide little or no shelter for young fish as they travel along the channel. About 80 percent of native Great Lakes fish rely on wetland ecosystems for part of their life cycle, but especially in urban areas along the Great Lakes, these ecosystems no longer exist. Now, a new technology tries to mimic the conditions in wetlands that benefit small, young fish as they make their way from the stream to the lake. Researchers are installing small containers filled with wetland plants and soil that are attached to steel bulkheads along the river. The containers float up and down with the changing water level. The plant communities also support life on the bottom of the food chain, thereby also providing food for the young fish that shelter in the plant life.

Resource Challenges Addressed

  • Lack of shallow water habitat
  • No place for fish to safely swim upstream
  • Lack of food for fry fish


A person in a boat begins the installation process in the Milwaukee River

The installation of floating islands involves securing them to the iron bulkheads that line the Milwaukee River. Photo credit: Marek Landscaping.

Results and Accomplishments

The floating habitats have allowed fish to return to the Milwaukee River and find food and shelter. Biologists have seen large mouth bass and green-eared sunfish more frequently in the river. In addition, ducks, muskrats, birds, and frogs all take advantage of the small, simulated shoreline habitat. In addition to these small floating containers, larger versions of the idea are being implemented—islands. The engineered islands are larger versions of the containers, at about 80 feet long in six segments, and will be easier to remove from the water during the winter when the freeze/thaw cycle of the ice makes it difficult for the floating mechanism in the containers to work.

Close up example of plants used in floating islands

A close-up view of the floating habitat containers. These habitats simulate the nearshore ecosystem, allowing small fish, biofilm, frogs, and other wildlife to thrive. Photo credit: Marek Landscaping.

An example of a floating island in the Milwaukee River

Newly installed floating island. Larger than the floating habitat containers, these islands are easier to maintain, all while providing the same services to wildlife. Photo credit: Marek Landscaping.