From Westcliffe, head south out of town on SH69 as though going to the South Colony Lakes area by the Crestones. Drive 4.4 miles south from the intersection of highways 69 and 96 in town, then turn right onto CR119 (Colfax Lane) and drive 5.5 miles to the junction where if you turn right, you'd be heading for the Crestones and South Colony Lakes. But instead of turning right, turn left, to the east, then in a few hundred yards, (quarter mile) the road again turns abruptly south and in about 5 miles comes to a trailhead parking area where passenger cars should give it up. This is the Rainbow trailhead here. Coordinates for this lower parking area at 9300 ft. are: N37° 55' 49.07" W 105° 27' 26.52".
If you have 4WD with good clearance, then proceed up the steepening 4WD road to the south and west for another 2.5 miles (appx.) to the upper trailhead at the coordinates and elevation given above. Our first drive up this road in 1995 was made in a Jeep Cherokee Sport. We found the road in surprisingly good shape, even though it was a steep single-track type road. In 2005 we returned to the same area in a Toyota T-100 pickup. In those 10 intervening years, the road condition had deteriorated considerably. It proved more of a challenge in our longer-bed vehicle, but we still made it okay. In any event, be prepared for a rough ride on a steep, narrow road with difficult rocky stretches. Reaching this upper parking area will greatly shorten the suggested backpack.
Primitive camping is available at both the upper and lower trailheads. There are no close by National Forest Service campgrounds.
A short and sweet backpack over Music Pass and into upper Sand Creek can set you up for access to the numerous 13ers that surround this basin. In fact, there are 10 accessible summits that could all be climbed in as little as 3 - 4 days depending on your pace and endurance.
From the upper trailhead parking, hike 1.35 miles on Trail #1337 to the summit of Music Pass at just below 11,400 ft. The trail starts out through forest where in early summer you may still find, patches of snow, snowbanks and resulting muddy spots. As the trail approaches the pass, it climbs more steeply and ascends out of the forest. At the top of the pass, you'll enjoy an expansive and very impressive view of the upper Sand Creek Basin and all the surrounding 13ers. Once you cross the pass, you'll be entering the "Great Sand Dunes National Preserve."
Once you've soaked in the view, follow the good trail as it drops NW into the Sand Creek drainage. There's a large meadow that extends for over a mile mostly on the east side of the creek. At the upper end of that meadow, just before the trail enters the forest, there are good campsites at approximately these coordinates: N 37° 56' 06.97" W 105° 31' 20.53" Elev. 11,060 ft. This location can serve as an excellent base camp if you don't want to move your campsite. It's 2.6 miles to here with no more than 750 feet of gain, some of which you lose. As trail #1337 drops into this meadow, it will intersect trail #743 coming in from the San Luis Valley side. So in a little over an hour, you can be in a great wilderness location and setting up your tent. Don't be surprised however, if you're sharing this location with some other groups. This seems to be a popular destination, especially weekends and long weekends.
If you desire a campsite closer to your peaks of choice, then there is also good camping at both Lower and Upper Sand Creek Lakes. We have camped at the lower lake and found several good campsites on the east side of the lake and on the north side of the outlet. To get there, you'll need to cross Sand Creek near where the trail enters the forest. There may be more than one trail in this area and crossing the creek can be difficult in runoff conditions. Once across, the trail heads NW along the creek for a ways before branching and turning SW and winding its way to the lower lake over a distance of about one mile and 430 feet of gain.
The main Sand Creek trail also continues up valley to Upper Sand Creek Lake which can serve as a good camp location for accessing Milwaukee and Pico Aislado. This trail may or may not go as indicated on the USGS topo map. When we climbed here in 1995, that summer followed on the heels of a heavy snow winter and most everything above 11,000 feet in this valley was still covered in snow. To gain Upper Sand Creek Lake will add 1.55 miles of hiking and another 700 feet of gain.
There is camping as described above at 11,060 ft. at the upper NW end of the long meadow and at both Lower and Upper Sand Creek Lakes.
There are two difficulties in describing our route to Milwaukee Peak. The first has to do with the 1967 Crestone Peak quad which shows a trail that leads from near Upper Sand Creek Lake to a pass (Milwaukee Pass) just north of the Milwaukee summit and between it and a northern sub-summit. On that quad, that trail is in a drainage separated from the headwaters of Sand Creek by a prominent ridge. This trail does not seem to actually exist any longer. It appears that a trail route now follows more in the Sand Creek headwaters and comes out at the Milwaukee/Marble saddle. In addition, when we did this climb, as mentioned before, there was so much snow, locating any trail was impossible anyhow. So you might want to supplement our description with the G&M description of Pico Aislado and a report by Ryan Schilling on SummitPost here:
We have sequenced Milwaukee with Pico Aislado and also Marble Mountain. Leaving Marble for another day can easily be done if this 3-peak sequence is too much for one day or weather forces a discretionary retreat, which is what we SHOULD have done. As for our route, because we wanted to avoid snow and willows as much as possible, from a camp location at the end of the long meadow at 11,060 ft., we headed north, first cutting through forest, then hiking along the edge of the forest and took a wide-swinging arch path to the NW, gradually ascending on mostly tundra. At one point we had to cross some talus slopes with rocky rubble, after which, there was a steeper gain into the head of Sand Creek, followed by more tundra hiking (we assume) to the saddle between Marble Mountain and Milwaukee Peak. This route is shown on the Google Earth image by a red line. On the map we supply, we show both possibilities, though most everyone seems to use the trail to the Milwaukee-Marble saddle.
From this saddle, head SSW following the steepening ridge crest on tundra and rock. We crested the false summit north of Milwaukee and picked up the trail coming up from the Cottonwood drainage which we were able to follow for about 100 yards, but then left it to continue along the ridge to a saddle (13,300 ft.) followed by a notch mentioned by G&M and Ryan. Drop (i.e. - downclimb) into the notch and then the challenge begins. It's not that far to the summit, but it won't be easy. Literally climb a short section of rock wall (4th class) and then locate the ramp/ledge that goes south along the east face of the peak. It's very obvious. The ledge is narrow and exposed and can be intimidating for some. This is the crux. We found this ledge to be similar to the ledge you follow on the east side of Pyramid Peak, before you begin the final, more vertical ascent to the summit, but far less extended. The ledge led to an obvious trail that switchbacked up about 20 feet onto steeply pitched rock and tundra ledges. We climbed upward another 30 feet or so before finally reaching terrain where it felt safe to stand and walk. That's the end of the 4th class section. Regaining the summit ridge, from here, stroll/clamber on to the true summit.
Many if not most climbers, once they top Milwaukee will want to continue on over to Pico Aislado. From Milwaukee, you have a clear view of the route over, so as you rest and munch on your lunch, plot your ascent over. From this perspective, Pico Aislado is very impressive and a little intimidating. To descend Milwaukee, return as you came, but keep in mind that from the Marble-Milwaukee saddle, it's easily possible to hike all long the ridge over to Marble Mountain and then drop back down to the camp location at 11,060 feet.