Illinois once harbored more than 8 million acres of wetlands. By the 1980s, all but 1.2 million wetland acres had been lost, filled in for development or drained to make way for agriculture. Now, thanks to a 2023 Supreme Court decision, roughly 72% of the remaining 981,000 acres of Illinois wetlands are no longer protected by the federal Clean Water Act, putting communities at risk of losing the flood control, groundwater recharge, water purification and natural habitat these wetlands provide, researchers report.