Approaching the summit boulders
This is a short route to the summit of this nice, lower peak. The route starts by gaining very little elevation then rapidly gains elevation on grassy slopes to the rocky summit area. Visibility is good and the navigation is very straightforward.
Threemile Mountain from meadow On the southeast slopes, looking at summit
From Hartsel, Colorado, near the intersection of US Hwy 24 and CO Hwy 9
• Follow CO Hwy 9 south for approximately 15 miles.
• Turn left / northeast on Park County Road 116.
• Follow CO Rd 116 about 1 mile northeast to the turnoff for Forest Service Road 270.
• Turn right on FS 270 and park.
• From your parking area on the east side of CO Rd 166, carefully cross CO Rd 166 and head northwest across a pasture for less than ½ mile toward the base of the southeast slope of Threemile Mountain.
• Enter the southeast facing drainage and begin your ascent. The going becomes quite steep as the route begins to curl toward the summit, but the footing on prairie grasses is solid.
• Reach the high saddle between summits and turn sharply east toward the true summit.
• The highpoint is marked by a summit cairn and, at the time of my visit, a simple summit register is contained in a jar.
• Enjoy the views from the summit of nearby mid-elevation mountains along with high-country in the distance before retracing your steps back to your vehicle.
• WINTER - Flotation (snowshoes would be ideal given that much of the route travels steep, densely-timbered slopes).
• Trail Map (Either the USGS Castle Rock Gulch quad or a custom map will be necessary)
• Colorado Gazetteer or similar roadmap illustrating minor/dirt roads.
• Compass or GPS
• Water and snacks
• WINTER - Insulated, water-proof boots
• First aid kit