Chama River Trail & FS 121
Off of Highway 17 in New Mexico is the Rancho del Oso Pardo (a very noble and beautiful piece of privately held land that seeks to return this gorgeous countryside and the animals that inhabit it back into its natural state) which sits on FS 121/445. At the end of this road, which crosses into Colorado, is public land in the form of the Rio Grand National Forest which includes the Chama River Trail, horse stables, and the Chama Basin Trail.
You cannot stop or explore the privately held Ranch but you can hike into the Southern San Juan Wilderness via a few trails which take you past many waterfalls and mountain peaks. The area is beautiful and I will explore it one day so check back next season.