To reach Trail #509 if coming from Ouray: Drive to the summit of Red Mountain Pass on US550. Begin measuring here and continue driving south on US550. The first turnoff of two possible access points will come not long after the big switchback and the section where the highway opens up and heads back south. The turnoff is 4.2 miles down from the summit of the pass. Turn right (west) onto a gravel road that drops down toward Mineral Creek and heads back north following the creek. This is FR820. It does not show on the 1955 Silverton quad, but it does show on the San Juan NF map and the FS Topo 2016 maps. The road will come to an area of avalanche damage and at that point, you must drive a short distance in and across the creek to continue on the road. In lower water conditions, this is no problem even for passenger vehicles, but in runoff season, the flow may be strong enough to discourage use of this access. Once across the creek, the road switchbacks up the hillside, with open, primitive campsites at each of the switchbacks. At the 3rd switchback, the road heads south and climbs very steeply to an area of parking where it crosses an open drainage. Just beyond there, it crosses just below an old mine. There is parking in this area for several vehicles, but the actual trailhead is still .2 miles south along the same road. You could even car-camp here, but there's no privacy. To get to the actual trail, continue south along the road the additional .2 mile and there will be a couple other pullouts, each of which can accommodate two to three vehicles. The trail is marked by one of those brown, flexible fiberglass posts and is identified as Trail #509.
Alternate access: From the summit of Red Mountain Pass, drive south on US550 past the first turn at 4.2 miles and drive another .7 mile to the turnoff for Ophir Pass on the right (west). If coming from Silverton and the "Y" intersection on the west side of town, it's 4.7 miles up to this turnoff. The Ophir Pass Road is marked with a brown sign with writing on either side of the sign. When you turn onto this road, it will drop down and cross Mineral Creek on a good bridge, then will head SW and begin climbing uphill. On the way down to the bridge, you'll pass two possible campsites. It's .2 mile to the bridge, then another .2 mile up the Ophir Pass road to a turnoff to the right for the trailhead road - FR820. This section of the road to the trailhead is a little rougher than the one from the north, but passenger cars carefully driven can likely make either approach successfully. Better clearance vehicles will have an easier time.
For additional information regarding this trail, see this link: https://www.fs.usda.gov/recarea/sanjuan/recreation/hiking/recarea/?recid=42832&actid=50 or read our route description for UN 13,159.
From the north access road, there is room for a vehicle and a primitive camp at each of the first two switchbacks. From the south access, there are two primitive campsite locations; one just after you turn off the highway, and the other a little farther down. We did not see any good tent campsites along the trailhead road. You could also car-camp at one of several pullouts along FR820. The closest campgrounds will be found along the South Mineral Creek Road - but this area is crowded all summer.