BLM land just outside the south (main) entrance to Black Canyon National Park. Road can be rough, especially slippery mud after rain. Many dispersed sites with cleared space and fire rings along the road, which goes for miles. Reserved campsites within the National Park can be difficult to get … there's no shortage of sites here, just outside. There's a small store at the junction of the Park access road with US 50, selling firewood, ice, and necessities. Montrose is a short 15 miles away for more substantial needs (gasoline, repairs, shopping).
The Prospector Campground in White River National Forest is on the Shadow Mountain Road, off the east end of Dillon Reservoir, easily accessible from I-70 heading toward Keystone and Arapahoe Basin. It's well-managed, with the plentiful toilets getting twice-daily service from the genial hosts. Like most National Forest campgrounds, reservations can be made on line, a good idea during busy summer weekends. In addition to the gorgeous scenery, what was impressive about Prospector is the size and spacing of the campsites … you're not right on top of your neighbor, but you're still on a level pad with a fire ring at every spot.