Oregon ATV permits are required for any vehicle traveling off pavement, and are sold at Oregon Parks and Recreation Department. You have to display the ATV permit if you are operating your ATV on public land (and even then, the land must be specifically designated for ATV use). Mufflers in Oregon must be maintained at 99 decibels. Lower levels are required at Sand Lake and Oregon Dunes National Recreation Area.
ATV's must have a red flag displayed nine feet above the ground when riding on sand.