Removing Culverts, Dams, and Obstacles

Restores Passage to River

Removing dams, culverts, and other obstructions along the upper Milwaukee River has reconnected more than 100 miles of streams, allowing native fish like northern pike to return to parts of the river they had been cut off from.


The stretch of the Milwaukee River near the villages of Thiensville and Grafton had tributaries clogged with invasive plants and low culverts preventing aquatic species from easily traveling upstream. A dam across the river outside of Grafton was also impeding the natural flow of the water and aquatic life. The historically connected riparian zone had been fragmented until Ozaukee Planning and Parks department developed a plan of action. While lower portions of the Milwaukee River have been significantly altered through urban development, the portion in Ozaukee County had more intact spawning habitat and other high quality habitat relatively preserved. The parks department removed over 180 impediments to fish and wildlife passage—including two dams—which helped reconnect more than 100 stream miles. Fish returned to places where, for years, they have been blocked from swimming.

Resource Challenges Addressed

  • Blocked natural river flow
  • Invasive species


A culvert opens a pathway for fish between waterways

The Ozaukee County Highway Department installs a fish passage culvert near Daly Lake on the Riveredge Creek. Shady Lane Road crosses this creek, causing the need for the culvert. Credit: Ozaukee County Planning and Parks Department.

Results and Accomplishments

Fish and other aquatic life have been able to move throughout the river, thanks to the removal of two large dams and over 180 smaller impediments. Other dams remaining in the area now have natural fish passageways to connect the upper and lower parts of the river. Other portions of the river and its tributaries are being returned to an increasingly “wild,” or meandering, state that is better for the health of aquatic life. This state will help northern pike and other native fish as meandering rivers are a more suitable habitat for them. Floodplains were constructed or identified, to help prevent floodwaters from reaching communities along the river.