Green Mountain Trail is a 15.2 mile moderately trafficked out and back trail located near Prineville, Oregon that features beautiful wild flowers and is rated as difficult. The trail offers a number of activity options and is best used from March until September.
Directions from Prineville: travel north on McKay Road, 12 miles to Forest Road #33, right turn on Forest Road #33, travel 6 miles east to Harvey Gap.
Due to lack of info just sharing what I found. I have not completed this hike yet.
This is a scenic ride over rolling terrain through juniper and pine forests and openings between Harvey Gap and Forest Road 3380. The north end of the trail is accessible from the Wildcat Campground by a long (5 mile), uphill climb on a good gravel road to Harvey Gap. The trail is wide and there is the possibility of meeting an ATV, motorcycle, or horse. This eight-mile trail is classified as "more difficult" because of a series of short, rough, steep sections. The return trip to Wildcat Campground is a steep (5 mile), downhill ride on a secondary gravel road (Forest Road 3380) to the intersection with Forest Road 33, then north for 5 miles back to Wildcat.
Read more: http://www.gorp.com/parks-guide/travel-ta-ochoco-national-forest-biking-oregon-sidwcmdev_066510.html#ixzz3lFRRLE6V