From the town of Buena Vista, turn west from US285 onto CR306, also known as the Cottonwood Pass Road. Drive 7.7 miles on pavement to an intersection and turn left (south) onto CR344 for Cottonwood Lake. Drive 3.6 miles on graded, gravel road to the east end of the lake where there's a picnic ground. West of the lake, thee's a forest service campground. See details below. From the east end of the lake and the turn off for the picnic area, drive west another 3.35 miles on graded gravel to the Hope Gulch TH. The turnoff can be easy to miss and is on the left (south) side of the road.
The Cottonwood Lake CG sits a little beyond the west end of Cottonwood Lake and is forest service maintained. There are 28 sites. Water and vault toilets are available. As with most such campgrounds, they tend to fill completely on summer weekends. This is a first come, first serve campground.
Beyond the campground, (west) there are several at-large, primitive sites including at the trailhead as well. Be aware there are private property parcels along this road.