Roadless Rule protects drinking water for 25 million Americans

For almost 25 years, the Roadless Rule has kept parts of America’s national forests largely untouched by logging and road building. The policy safeguards nearly 60 million acres of public land throughout the United States.

Researchers now say these protected forests are crucial sources of clean drinking water for at least 25 million Americans.

In Colorado, New Mexico and Montana, the protected forests supply drinking water for more than one-third of the population.

The findings come as the Trump administration seeks to revoke the rule, which would remove the federal restriction on logging and new roads in these places.

The researchers caution that removing the safeguards could damage rivers relied upon by millions and increase the expense of treating drinking water.

Water for millions

The Roadless Rule applies to about one-quarter of the nation’s National Forests: land identified decades ago by the Forest Service as having no roads.

As the protection was established by a federal agency rather than Congress, it can be removed through a comparable administrative action. The current administration started that process in 2025.

To assess the potential cost of repeal, the researchers mapped every watershed supplied by roadless areas. Around 25 million people obtain drinking water from these lands.

Just a small proportion live in the forests’ local catchments. The majority are as far as 161 kilometres downstream, where the rivers ultimately flow to their taps.

Measuring the Roadless Rule’s benefits

Julian D. Olden of the University of Washington (UW) in Seattle led the research, alongside colleagues from the research non-profit Conservation Science Partners (CSP).

Olden and his fellow authors aimed to quantify benefits that are generally not measured.

In an email to Earth.com, he said, “It is difficult to overstate the importance of roadless areas for people and nature.” He also noted that the rule has remained popular with most Americans since it was introduced.

Forests filter water in an understated fashion. Their tree canopies and soils intercept rainfall, slow its movement and allow it to seep into the ground.

At the same time, roots and soil microbes remove pollutants before the water enters a stream.

Logging roads disrupt this process. Cleared areas and exposed soil send sediment into rivers, making water murky and requiring treatment plants to work harder, or to close until sediment concentrations decline.

Rivers and their backups

In the contiguous 48 states, roadless areas protect approximately 132,000 kilometres of rivers and streams. This represents about 2.5% of the country’s flowing water.

For most of those waterways, the rule provides the sole substantial protection. The researchers distinguished between rivers with other safeguards and those without them.

If a river also passes through a wilderness area or supports federally listed species, other legislation would remain in force after a repeal.

After excluding those rivers, roadless protection alone covers roughly 100,000 kilometres, or nearly 2% of all US rivers. The risk is not limited to western states.

Idaho depends most heavily on the rule, although it also safeguards extensive river stretches in eastern states with limited public land, including Virginia, West Virginia and North Carolina.

In more than 2,000 watersheds, roadless areas account for over one-third of the total river length.

Healthy forests, lower costs

Because water is transported and traded between basins, a change to one forest can affect cities hundreds of kilometres away. Run-off from North Carolina’s Pisgah National Forest contributes to supplies for Asheville and Charlotte.

Water linked to Utah’s Ashley National Forest reaches Salt Lake City, Las Vegas, Los Angeles and San Diego. Several individual forests supply very large populations.

The Angeles National Forest, in the mountains above Los Angeles, feeds water systems serving more than four million people.

It is among nine national forests, each of which supplies more than one million Americans. The financial consequences of losing these protections are well established.

When source water becomes more polluted, utilities spend more to treat it. A recent paper predicted that upstream changes in land use would reduce water quality at drinking-water intakes throughout an entire river basin.

Savings work in the other direction too. One assessment concluded that seven US cities saved millions of dollars in treatment costs by protecting their source watersheds rather than constructing new facilities.

Recreation and wildlife

The same watersheds feature on maps used by hunters and anglers. More than one-quarter of watersheds influenced by roadless areas are among their states’ leading fishing and hunting locations.

These forests include thousands of kilometres of trails and hundreds of routes suitable for paddling.

When Earth.com asked what these lands provide, Olden said, “Roadless areas offer free or affordable access to public lands that support far-ranging outdoor pursuits such as hunting, fishing, camping, hiking, skiing, and paddling.”

Much of this access relies on the intact, undeveloped character preserved by the rule. Biodiversity presents a comparable picture.

More than clean water

Rivers flowing through these areas support approximately 1,500 native fish, amphibians, crayfish, molluscs and turtles.

The watersheds with the greatest wildlife richness are largely different from those valued for sport. The breadth of that difference can easily be understated.

One study concluded that more than half of the nation’s at-risk wildlife species have suitable habitat in roadless areas, despite those lands covering only 2% of the contiguous 48 states.

Logging and logging roads influence waterways even where activity remains on land. Sediment, higher temperatures and reduced shade change stream habitats.

About one-fifth of the country’s freshwater fish are associated with forests. Off-road vehicles travelling on former logging roads create an additional source of disturbance.

The value of roadless forests

Before now, the advantages of leaving these forests undisturbed had largely been claimed rather than quantified.

The new research measures them for the first time, encompassing the drinking water of 25 million people, tens of thousands of kilometres of rivers and habitat for well over a thousand species.

Much of this has no legal alternative protection if the rule is repealed. The implications extend beyond water and fish.

An earlier analysis found that roadless areas expand and link the country’s wilderness areas and parks, shielding them from development along their boundaries.

The costs of repeal

Roadless areas have substantially fewer human-caused wildfire ignitions than areas close to roads, where almost four times as many ignitions have been recorded. Recreation could also suffer directly.

In response to questions from Earth.com, Olden said, “This suggests that weakening the Roadless Rule could put these recreational opportunities at risk.”

A draft environmental review and proposed rule are anticipated in mid-2026, while the first public-comment period has already received more than 625,000 responses.

Should the ban be removed, new logging and road construction could resume in areas that have been off limits for a generation, leaving the water, rivers and wildlife assessed by the study without their strongest safeguard.