GOOSE ISLAND — Hundreds of baby mussels are growing in boxes beneath platforms that bob on the Chicago River’s North Branch, part of a project to revive the waterway.
After years of the river being a polluted industrial channel, advocates have worked to turn the river into an eco-park. The work is spearheaded by Urban Rivers, an environmental nonprofit trying to replenish and restore the river’s ecosystems.
Through reviving the population of freshwater mussels, the organization wants to transform how people perceive the water, which was once notorious for its foul odor, Urban Rivers Executive Director Nick Wesley said.
“Many people still associate the Chicago River with chemical waste and pollution,” Wesley said. “But there is actually a huge improvement in the water quality, and we wish people can rediscover how the river is a true asset to the community.”
This summer, the group unveiled the first phase of its Wild Mile project: a floating platform, gardens and walkways that are part of a park focused on wildlife. Nestled along the park are the boxes of mussels.
Freshwater mussels play an integral role in Chicago’s water system, said Phil Nicodemus, Urban Rivers’ research director. Once abundant in the Chicago River, they consume algae and plankton and clean up the water by removing sediment, Nicodemus said.
That changed in the 1850s, when the river became popular for commercial transportation and a dumping ground for nearby industries, Nicodemus said. During its peak, the river’s South Branch became so polluted with blood and entrails from meatpacking factories that the gasses began to bubble out, giving its nickname, “Bubbly Creek.”
The construction of the interstate highway system in the mid-20th century took the transportation load off the Chicago River, but the environmental damage has been done, Nicodemus said. Freshwater mussels — one of the most endangered species in the world because they are particularly sensitive to their environment, according to the U.S. Fish and Wildlife Service — have largely disappeared from the Chicago River, despite its water quality improving after the passage of the Clean Water Act in 1972, Nicodemus said.
For mussels to grow, there have to be hard surfaces for them to burrow into, Nicodemus said. Female mussels release larvae and attach them to the gills or the fins of host fish, and the baby mussels fall to the bank after they grow to a certain size and glue to hard surfaces.
But with decades of human activities, the river bank is covered with layers of very fine sediment from chemical waste and is unable to support mussels’ growth, Nicodemus said.
“We introduced a lot of fertilizers and contaminants and screwed up the bottom layer,” Wesley said. “We need to correct the wrongs.”
In 2020, Urban Rivers launched a mission to revive freshwater mussels in the Chicago River. The following year, Nicodemus discovered a female mussel stuffed with larvae, which produced about 1,000 offspring, he said. The team installed wooden boxes along the artificial park as temporary habitats for the juvenile mussels until the mussels grow big enough to be replaced in the river.
So far, Urban Rivers has helped reproduce more than 1,500 mussels. These mussels improve the water quality by filter feeding and removing pollutants, Nicodemus said.
Artificial boxes are only a temporary solution, Nicodemus said. In the future, Urban Rivers plans to create a new river bottom by installing rock and sand to cover up the fine, pollution-laden sediment. By then, the mussels could self-reproduce in the river without human intervention, he said.
“After that, the sky is the limit,” Nicodemus said.
Urban Rivers has now built a variety of microhabitats to support animals in the ecosystem. On the floating wetland, people can see dragonflies and butterflies among the plants, while fish swim in the water beneath.
The organization also organizes community events such as kayaking and workshops to encourage people to learn about the river’s ecosystem. The group wants people to appreciate the river by understanding how everything is connected in nature, organizers said.
“Many people don’t understand how much nature is working for our benefit behind the scenes,” Wesley said. “Mussels are the natural filters of water. They are deeply intertwined with people’s own health and well-being.”
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