Motorized trail use also remains very popular with some people. Such terms as ORV, four-wheeling, all-terrain vehicle, and others actually have highly specific meanings. In the United States, this sport remains very popular. The Recreational Trails Program defined as part of the Intermodal Surface Transportation Efficiency Act of 1991 mandates that states must use a minimum of 30 percent of these funds for motorized trail uses.
Off-road vehicle use on public land has been criticized by some members of the U.S. government and environmental organizations including the Sierra Club and The Wilderness Society. They have noted several consequences of illegal ORV use such as pollution, trail damage, erosion, land degradation, possible species extinction, and habitat destruction which can leave hiking trails impassable. ORV proponents argue that legal use taking place under planned access along with the multiple environment and trail conservation efforts by ORV groups will mitigate these issues. Groups such as the Blueribbon Coalition advocate Tread lightly, which is the responsible use of public lands used for off-road activities.
A British Columbia Ministry of Forests forest service road in steep terrain. The Lower Seymour Conservation Reserve near North Vancouver, British Columbia, Canada.
Noise pollution is also a concern and several studies conducted by Montana State University, California State University, University of Florida and others have cited possible negative behavioral changes in wildlife as the result of some ORV use. Some U.S. states have laws to reduce noise generated by off-road and non-highway vehicles. Washington is one example.