Jeremy Poland / Getty Images A tour boat passes under the bridges of the river that runs through the cityJeremy Poland / Getty Images
Golden shiners, spotfin shiners, black crappies, bluegills, largemouth bass, and other species are now spawning in the once heavily polluted Chicago River, indicating that efforts to clean up the waterway are working. From 2020 to 2022, Austin Happel, a biologist at Chicago’s Shedd Aquarium, collected 2,211 fish larvae of 24 species, identified by genetic sequencing. Fish tolerant to pollution were more common in the North Branch, while the South Branch was home to a greater number of intolerant species due to submerged vegetation, water quality, and protection from predators offered by unused barge moorings. The river, measuring 250 kilometers, runs through the city of Chicago. The quality of its water improved significantly following a 1972 law and the work of organizations such as Friends of the Chicago River, Openlands, and Urban Rivers. Researchers had already identified nearly 60 species of fish living in the river but did not yet know how many were spawning in its waters (Journal of Great Lakes Research, September 17; Smithsonian Magazine, September 22).
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