UN 13,015 (formerly UN 13,020 interpolated) near Maroon Lake and Willow Pass has been determined to be no longer a ranked summit per Lidar evaluation, which gives it 292 ft. of prominence. This has reduced the total number of ranked 13ers from 584 to 583.
From CO135 on the east side of Crested Butte, turn west onto Whiterock Ave. and drive west through town. This street becomes CR12. It's a paved road for several miles as it climbs west out of town, then turns to good quality, graded gravel, then returns to paved again, shortly before the turnoff for Lake Irwin. That turnoff will come in a large, open meadow area and about a half mile east of the summit of Kebler Pass. Turn right onto FR826, at a signed intersection that will indicate Lake Irwin is two miles north, up the road. Almost immediately, a road veers off to the right, though it could get you there, we recommend staying left and continuing on CR12E to the lake. It's about 9 miles from town. Drive to Lake Irvin on a graded, gravel road, passable to passenger cars. The road comes to a parking area with a vault toilet and half a dozen picnic tables lower down. From there, passenger cars may continue by driving across the spillway dam. Go on past the entrance to the campground. Drive uphill, veering right at another junction and continue to an open, flat ridge and another intersection with some cabins. Go right and follow the road down through a couple switchbacks and down to cross the drainage. Then continue following the road as it begins to climb up, now heading in a SE direction. Where the road begins to make this upward climb is where some lower clearance passenger vehicles may encounter some rough spots and rocks. This road continues SE to a switchback, then turns nearly north and continues to climb steadily. Soon, the road terminates at an old lodge, no longer in use. Parking right at the lodge is not permitted. You must park farther back down the road, then hike up to the lodge to locate the trailhead on the west side of the lodge. On the last segment of road after the switchback, you will see pull-offs for parking.
A word of explanation: Most of the land above Lake Irwin on this west side and above the campground is privately owned. We visited here in the summer of 2019. There was a man who patrolled the area on an ATV who would stop hikers who appeared to be heading onto the private land and politely inform them that they could not utilize certain roads. He was also polite enough to direct hikers to where they could go and park and those are the directions we are providing here. The man informed us that the land holders and the Forest Service were presently in negotiations regarding access for hikers, bikers, etc., to this area. Since such negotiations can take up to years, this information may or may not be outdated. If you visit this area and find a different situation, please advise us so we can update here on the website. The map we provide should help ascertain how to get to the trailhead.
Once you turn off from CR12 and along the two mile drive to lake Irwin, there are a couple at-large, primitive sites off the road. At the lake, there is a sizable, National Forest campground. It has both vault toilets and potable water, firewood & trash. Some of the sites may be reserved in advance, others are first-come, first-served. There are 32 sits and just outside the campground, there are a couple other spots where you may be able to set up, but do so at your own risk of being run off. Here is a link to the Gunnison NF website and this particular campground: https://www.fs.usda.gov/recarea/gmug/recarea/?recid=33340.