WASHINGTON (AP) – The Forest Service will propose restricting many off-road vehicles to designated roads and trails in federal forests and grasslands in an effort to curb environmental damage and ease conflict between visitors.

Under the proposal, which Forest Service Chief Dale Bosworth is to announce today, all 155 national forests and 20 grasslands would work with the public to identify routes, trails and other areas suitable for off-road vehicles.

An environmental analysis would be required on each site to determine potential environmental effects.

The plan is intended to halt the proliferation of roads and trails – many of them illegal – that have sprouted in public forests nationwide.

Bosworth calls unmanaged recreation one of the four major threats facing the Forest Service, along with wildfires, invasive species and loss of open space.

The new national policy, several years in the making, would restrict all-terrain vehicles, motorized trail bikes and other off-road motor vehicles to designated roads and trails on nearly 193 million acres of public land.

The plan, which is similar to a draft released last year, comes as use of off-road vehicles reaches new heights. In the past three decades, the number of off-road vehicle users has increased sevenfold to about 36 million, causing conflicts with other users such as hikers, horseback riders and the growing number of homeowners who live near national forests.

Environmentalists and hunting and recreation groups called the draft proposal a good start but said the final plan should include more effective enforcement and money to pay for it.

Unmanaged recreation is an agency problem as well as a user problem, said Don Amador of the Blue Ribbon Coalition, an Idaho-based group that advocates motorized recreation. Amador said most off-roaders are responsible and have been unfairly singled out by officials.

Amador’s group wants to ensure that trails and open areas now used by all-terrain vehicles remain accessible to riders.

A spokesman for the Wilderness Society supported the draft plan but said the real test will be in how the final rules are enforced.

“These regulations are not going to be worth the paper they’re printed on if there are not the dollars and the resources to do the planning and enforce the rules,” said Scott Kovarovics, director of the society’s natural trails and waters coalition.