“Signs of the river’s better health include visits from ‘Chonkosaurus,’ a giant snapping turtle who’s a global social media sensation. Chicago is so optimistic about the river’s improvements that the city plans in a few weeks to hold its first open water swim downtown in nearly a century. The tradition halted in the 1920s due to sewage polluting the water.

The river has come a long way since the days it bore the brunt of the city’s industrial might. 

Before train transportation, barges shipped goods to Chicago. To make way for large boats, the city dredged the waterway and installed steel walls, turning the river into a rectangular box and eliminating the gradual slope of the riverbed. The harsh environment wiped out the underwater plants that created habitats for fish as well as flora that pollinators frequented…

The Chicago River reached a low point in the 1970s. At that time, only five species of fish could survive in the polluted waters, Kurth said, including common carp, largemouth bass, goldfish, bluntnose and the gizzard shad…

In 1972, Congress passed the Clean Water Act, boosting the health of rivers across the country. Among its provisions, the act made it illegal to dump pollutants into navigable waters without a permit…

It’s thanks in part to that law that the number of fish species recorded by the Metropolitan Water Reclamation District in the Chicago River leapt from 10 to 77.”

From Inside Climate News.