Colorado's best training runs: Mosca Pass Trail

<h3 style="text-align: center;"> When you just want to get away from all the usual places, find a trail, and run your heart out...</h3>

The Mosca Pass Trail brings the runner a stiff climb rate and challenging trail conditions. All photos by Alan Versaw.

The idea of the Colorado's best training runs series is to identify and describe some of Colorado's finest trail runs with easy accessibility. The trails described in this series will vary in many respects. Some of the routes are difficult and others are easy, but they will all be scenic, they'll all be trail runs, and they will all be easily accessible. This installment in the series covers the trail between the Montville Nature Trail in Great Sand Dunes National Park to the top of Mosca Pass, 3.5 grueling miles and 1400 feet of elevation away. Better still, in a state where wide open spaces prevail, you can almost imagine yourself in a place where deep forests are the norm as you enjoy this trail.

Most people who visit Great Sand Dunes National Park make a quick visit to the visitor center and then make a beeline for the main dunes parking lot. From there, the more energetic will wade through Medano Creek (in season) and head out in a northwesterly direction to the top of the dunes. And, there is no small amount of exercise involved in doing that. At about 8000 feet elevation and through all the challenges inherent in moving through loose sand, you will challenge both lungs and legs before reaching the top. As a matter of fact, running on the dunes was deemed ideal training for the United States distance runners leading up to the 1968 Mexico City Olympic Games.

Most visitors to the dunes pay little attention to the small parking lot and trailhead on the right just past the visitor center on your way to the main dunes lot. The few who do venture into the lot and on the trail that starts from that parking lot, however, are handsomely rewarded. 

For most who do visit, the parking lot serves as the point of departure for the Montville Nature Trail, a roughly half-mile loop through montane and riparian habitats. While the nature trail has a few rewards of its own for the environmentally curious, it is scarcely long enough or challenging enough to satisfy any self-respecting trail runner. 

If you're a trail runner, you would likely come here with something different in mind. And the Mosca Pass Trail can provide that element of something different that you seek.

As you start out on the trail, it will boggle your brain to realize that what is now a trail was once one of the primary roads into the San Luis Valley from the east side of the Sangre de Cristo range. The route served as a wagon road starting in the 1870s and lasting until a flash flood in rearranged the local rocks in 1911. The route was later rebuilt as a rough motor vehicle road and saw intermittent use from the 1930s through the 1950s. 

None of that is apparent today. Rather, in the narrow canyon through which Mosca Creek flows it is difficult to imagine the possibility of anything more than a single track through many portions.

After the part of the route shared with the Montville Nature Trail, the Mosca Pass Trail crosses a wooden bridge and starts climbing steeply to the east. For the next mile or so, the gradient is roughly 10% and rocky enough in places to qualify as technical trail running. Keep your eyes on the trail ahead, as there are many rocks, both large and small, and numerous exposed tree roots to negotiate. Occasionally, rockfall from the slopes on the north side of the canyon supplement the obstacles already in place:

In most sections, the Mosca Pass Trail is only wide enough for a single runner. The good news, however, is that you, or you and a friend or two, are likely to have the trail entirely to yourself. As I hinted before, this is an underappreciated part of the national park. 

At times, the gradient may be such that a shift from running to power hiking is the prudent decision. The gradient is relentlessly upward, with only very brief level or slightly downhill sections. In my experience, those sections are barely long enough to allow for even the slightest decrease in heart rate. You must measure you pace carefully, or the early section of the trail will beat you down. 

Throughout the first half of the ascent to Mosca Pass, the sounds of water in Mosca Creek are your constant companion, helping to divert your attention from the oxygen deprivation and calf burn. Other sounds might include territorial flights of Broad-tailed Hummingbirds, and the singing of Cordilleran Flycathers and Mountain Chickadees. In season, the wildflower displays can be stunning:

Throughout almost the entire ascent, the trail has a very deep-woodsy feel, as narrow-leaf cottonwoods, aspens, and firs come right to very edge of the trail. A quick glance to the slopes on the north side of the trail will reveal, however, that the lushly wooded feel of the trail does not extend far above the creek.

After about 1.5 miles from the trailhead, the trail itself becomes decidedly less rocky and the gradient relents a little. After careful pacing through the lower sections, if you have anything left, you can open up a little here. The trail winds its way in a consistently eastward direction but stubbornly hides from you any clear views of your destination almost until you have arrived at the top of the pass. 

The last little portion before the summit is one of the most open sections of the entire trail. To the north, the Sangre de Cristos climb, eventually toward the peaks of the Crestone group. To south south, the northern slopes of the Blanca group rise before you. The end of the Mosca Pass Road from the east greets hikers and runners who make the full trip to the top of the pass. The road from the east is only slightly more traveled than the trail from the west.

There is water along almost the entire route, but you should not attempt to drink unfiltered water from the creek. This run is demanding enough that you should bring your own water. Sunscreen is optional, but most of the route is shaded.

The trail can be run in conventional trainers, but trail running shoes are likely a superior option, if you have a pair. If you are running alone, let someone know where you're going and when you plan to be back. If something happens along the way, it could be a long time before a Good Samaritan happens by.

On your way down, you'll want to pay close attention to the trail ahead, but you'll also want to glance up every so often in the last mile for stunning views of the mass of the Great Sand Dunes below and rugged rocky outcrops above the trail to your right. 

If you camp at the dunes, or if you simply want to extend your run, the one-mile Wellington Ditch trail runs a mostly level course between Pinyon Flats Campground and the Mosca Pass Trail. 

Be warned that this is not an easy run. I confess, though, that I found it much easier in my early 30s when I was spending a lot of time in Alamosa completing my masters degree than I found it now in my 50s. It is not brutal; it is merely difficult. In addition to the technical factor through some of the lower sections of the canyon, there is also the average climb rate of 400 vertical feet per mile. That's difficult running under any circumstances, but somewhat more so at eight or nine thousand feet of elevation. The pass tops out at about 9700 feet.

As a final note, "mosca" is Spanish for fly, and biting flies can be common in parts of the San Luis Valley. On the worst days, biting flies and mosquitoes are a minor nuisance along the Mosca Pass Trail, mostly in the lowest portions where the trail is still part of the Montville Nature Trail loop. On the best days, you would never even know they are there.

National Park Service map of main portion of Great Sand Dunes National Park