CHAMPAIGN, Ill. — 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.
A patchwork of state and county-level wetland regulations offer some protection to those acres, but most are unprotected, the researchers found. Their study is detailed in the Journal of Environmental Management.
The 2023 Sackett v. Environmental Protection Agency decision followed decades of shifting guidance on the 1972 Clean Water Act. In 1985, "the U.S. Supreme Court unanimously held that wetlands adjacent to traditionally navigable waters are 'waters of the United States' and therefore protected by the Clean Water Act," the researchers wrote. That ruling allowed federal agencies to prevent the destruction of millions of acres of wetlands across the nation and preserve their natural functions.
But later Supreme Court rulings chipped away at that more inclusive definition of federally protected waters, culminating in the 2023 Sackett decision, which significantly narrowed the types of wetlands that were federally protected.
"The Sackett decision required that wetlands have a continuous surface connection to 'relatively permanent waters' of the United States and be indistinguishable from those waters," said University of Illinois Urbana-Champaign graduate student Chelsea Peterson, who led the new analysis with U. of I. natural resources and environmental sciences professor Jeffrey Matthews . "That removes protections from wetlands that flood infrequently, have surface connections to nonpermanent streams or are spatially isolated from permanent streams, which could be due to levees or dry land."
