The Forest Preserve District of DuPage County this week will release its 50,000th native freshwater mussel that was bred and raised at its Urban Stream Research Center in Blackwell Forest Preserve since 2012.

The District expects the landmark release to occur on Friday, Aug. 21, along Salt Creek at Fullersburg Woods Forest Preserve in Oak Brook, weather permitting. Ecologists have placed more than 9,500 mussels in the creek over the past month and will continue to do so through September. Over the past decade they’ve also had releases along both branches of the DuPage River, various tributaries, and in waterways managed by partnering counties.

The Salt Creek releases are especially significant because they would not have been possible without efforts by the Forest Preserve District, the DuPage River Salt Creek Workgroup, and the Metropolitan Water Reclamation District of Greater Chicago to drastically improve water quality along the creek.

Beginning in 2020 the DuPage River Salt Creek Workgroup spearheaded an ambitious plan that, in part, removed a 90-year-old dam, installed oxygen-generating riffles, and added 50,000 blueflag iris, swamp milkweed, marsh blazing star, and other native wetland plants along a mile of Salt Creek. The Metropolitan Water Reclamation District contributed $7 million in support of the $9.5 million habitat restoration project.

Although vital to keeping streams, lakes, and rivers clean, freshwater mussels are the most imperiled group of wildlife in North America. Raising them in captivity requires not only customized aquatic systems but also tanks of specific host fish, a must for the mussels’ complex development cycle. Both elements are at the heart of the Urban Stream Research Center, the only facility of its kind in Illinois.

Despite their size, mussels provide enormous benefits because they take in large amounts of water when they feed. In the process, they filter out bacteria, algae, and other microorganisms before passing clean water back into the water. Just one adult can filter up to 18 gallons of water in one day, and because many mussels like to live in groups, together they can filter enough water to lower overall water pollution levels.

The milestone reflects years of collaboration and investment to restore Salt Creek into a healthier waterway that can once again support native aquatic species while improving water quality for surrounding communities.