Denver ? The U.S. Forest Service on Wednesday proposed restricting many off-road vehicles to designated roads and trails in federal forests and grasslands as part of efforts to curb environmental damage and ease conflict between visitors.

Under the proposal, each forest and grasslands district would work with the public to identify routes, trails and other areas suitable for off-road vehicles.

An environmental analysis would also be required on each site to determine potential environmental effects, Rocky Mountain Regional Forester Rick Cables said.

The result would be a “use map” to outline what activities are allowed in which areas. The plan would also halt the proliferation of new roads and trails, helping ease maintenance and enforcement problems, Cables said.

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

“We think it’s well-intentioned, but it needs to be significantly strengthened,” said Suzanne Jones of The Wilderness Society’s Denver office.

Jack Troyer, the Forest Service’s intermountain regional forester, acknowledged the proposal does not include specific funding but said money for implementation and enforcement could be taken from budgets for specific areas within the agency.

Environmentalists, ranging from The Wilderness Society and the Sierra Club to the American Hiking Society, recommended that the agency set a two-year deadline for final implementation and immediately ban off-road vehicles from unauthorized routes.

The Blue Ribbon Coalition, a motorized recreation advocacy group, wants to make sure that many of the roads now used by vehicles remain open to them.

Executive Director Bill Dart said the Forest Service should focus first on heavily used trails near urban areas and gradually move to lesser-used lands.

If the proposed draft becomes final, it could take up to four years for the policies to take effect, but they could be implemented in some areas more quickly.

Between 1976 and 2000, the number of off-road vehicle users increased from 5 million to 36 million, causing conflicts with other users such as horseback riders as well as with the growing number of homeowners who live near national forests.