CHICAGO – One year ago, on July 31, 2018, the first jackhammer struck the dam at River Park where the North Branch of the Chicago River and the North Shore Channel converge on Chicago’s north side.
The four-foot high concrete North Branch Dam was a barrier to healthy ecosystems and was removed by the U.S. Army Corps of Engineers Chicago District.
The Friends of the Chicago River stated that the removal of the dam had been urged as far back as 2000, motivated by the prospects of easier mobility of fish and other wildlife, increased recreation, and improved water quality.
“We are happy to say that those improvements are coming to fruition with the removal of the concrete,” said Margaret Frisbie, executive director, Friends of the Chicago River. “Today, the area where the dam was located is an inspiring, more natural place that is yet another symbol of the revival of our great Chicago River system.”
Today, the dam is replaced by riffles to slow the flow of water and open a passage for fish to swim upstream. Other improvements to River Park include the removal of non-native grasses and wildflowers on banks, and established riparian savanna on banks and parkland natural areas.
“The plantings are now in their first year of establishment,” Jason Zylka, Corps ecologist said. “But as seeds germinate and live plant plugs fill in, the site will soon be a lush collection of native grasses and wildflowers.
River Park is soon to be a thriving and diverse ecosystem with natural vegetation, an abundance of fish and aquatic wildlife, and birds and other species that rely on the Chicago River as a food source.
“We are excited to learn that our coordinated efforts to improve water, urban biodiversity, and recreational quality along the riverbank have been fruitful,” said Cathy Breitenbach, Chicago Park District’s director of Cultural and Natural Resources. “The dam removal was an important first step towards the restoration of the ecosystem at River Park.”
All of this was undertaken through the Water Resources and Development Act of 2000, Section 506 Authority, Great Lakes Fisheries and Ecosystem Restoration Program. Section 506 focuses on the restoration of fish and wildlife habitat, removal of dams and other barriers to fishery migration, and the prevention and control of invasive species.
The dam was built in 1910 to accommodate for a four-foot difference between the North Branch of the Chicago River and the North Shore Channel, brought on by the reversal of the Main Stem and South Branch of the Chicago River 10 years earlier.
In the past 100 years since the dam was built, significant progress had been made in reducing flood risk and the resulting raw sewage overflow that would enter into the waterways. The sewage flushing duty of the North Shore Channel had been taken over by the Chicago Deep Tunnel Project, and the water quality of the river and channel has greatly improved.