The trail to Switzer Falls next to The Arroyo Seco in Angeles National Forest on March 13, 2024. Waterways located within the park provide water to much of Southern California. —Jeff Gritchen—Getty ImagesThe Trump Administration’s expected repeal of the “Roadless Rule” could impact drinking water supply for an estimated 25 million Americans, according to a new study out today in the journal PLOS Water. What is the Roadless Rule?In June 2025, the Trump Administration announced that it planned to roll back the “Roadless Rule,” a landmark 2001 conservation policy that prohibited roadbuilding and logging on nearly 60 million acres of federal forests. The aim of Trump’s repeal is to increase logging and encourage roadbuilding. The administration also claims that encouraging logging and construction will help address wildfire risks, though research has suggested that wildfires may be four times more likely to start near roads than in roadless forest tracts. The U.S. Department of Agriculture began the process to repeal the Roadless Rule last August. A final decision is expected in late 2026. As part of the Roadless Rule, it established a number of Inventoried Roadless Areas (IRAs), which are governed by regulations, and which protect over 130,000 km, or nearly 81,000 miles of rivers. In the new study published today, a team of researchers studied 2,488 protected roadless areas to determine how they contribute to river protection, how many people rely on them for drinking water, and the roles they play in hunting, fishing, and supporting aquatic biodiversity.What is at risk with the repeal of the Roadless Rule? IRAs protect roughly 2.5% of total river length in the contiguous United States. A total of 38 states benefit from river protection through IRAs, with the highest proportion in western states like Idaho, Utah, and Colorado, the researchers found. While 25 million people rely on watersheds influenced by IRAs, dependency varies by state. Five states—Arizona, California, Colorado, Georgia, and North Carolina—each have over 1 million people who source drinking water from roadless areas. In California, 24% of the state’s population depend on drinking water sourced from IRA-influenced watersheds, as do 58.9% of Colorado’s population, and 38.7% of New Mexico’s population. What’s more, the proximity of a number of National Forests to urban centers means that even states with small IRAs can have a large fraction of the population that is dependent on those waterways. The Angeles National Forest, for example, serves over 4 million public water service customers in southern California. Rolling back the roadless rule would impact water sources for millions, the researchers warn. Logging can degrade forested land—increasing the risks to watershed health and water quality. “Upholding the Roadless Rule and protecting forested areas from road construction and industrial logging make economic sense because they keep drinking water cleaner and cheaper to treat,” Julian Olden, professor in the school of of aquatic and fishery sciences at the University of Washington and lead author of the study, told TIME over email. “When watersheds aren’t well protected—for example, when logging and road-building disturb the land—water quality can suffer, sometimes forcing treatment plants to shut down temporarily, issue drinking water warnings, or find alternate water sources, all of which cost money.”That’s not the only economic repercussion a Roadless Rule repeal could have. The researchers found that it could impact a number of outdoor recreational activities. “Roadless areas provide free or low-cost access to popular outdoor activities like hunting, fishing, camping, hiking, skiing, and paddling, drawing millions of visitors each year,” said Olden. “[We] found that areas with strong roadless protections tend to overlap significantly with areas where hunting and fishing demand is highest—meaning that if the Roadless Rule were rolled back, it could threaten these recreational opportunities, which depend on keeping wild, undeveloped land intact.” The importance of protected natural areas cannot be overstated, says Olden. “By creating opportunities for new road construction and timber harvesting, rescinding the Roadless Rule may result in degraded water quality, loss of wildlife habitat, and fewer areas for people to enjoy America’s public lands for outdoor recreation.”