Backpacking Colorado's Four Pass Loop
Updated: Jul 20, 2022
When I think of what heaven must be like, I see myself standing in the middle of an endless aspen stand with warm sunlight pouring over me as the wind shuffles the leaves in the canopy and effortlessly lifts the beads of sweat forming on my forehead. I look out across the majestic mountain landscape and lose myself in the distant snow-capped peaks sitting in harmony like a string of pearls draped across the horizon. The joyful chatter of a red-crowned kinglet comes from a place unknown and the roaring of a crystal-clear creek can be heard in the valley below. I breathe in the cool mountain air and wonder why it's taken me so long to get here.
This scene is one we had the privilege of enjoying several times on our journey throughout the Maroon Bells – Snowmass Wilderness in Colorado’s White River National Forest. Our four-day, three-night expedition along the famed Four Pass Loop brought us high into the alpine tundra over four 12,000 foot mountain passes and then back down into mountain valleys with sweeping vistas and wildflower meadows. We trekked through subalpine forests cloaked in mystery and peace, forded many rushing rivers and traversed steep hillsides held together by the interconnected root systems of aspen stands. We were subjected to temperamental mountain weather, with mercurial shifts in pressure that resulted in driving hail followed by rolling clouds and then rain drops illuminated by golden beams of sunlight. And finally, stretching out across the sky in all their glory, rainbows appeared in a way that could have inspired even the most discouraged.
On this trip, Angie and I were joined by our friends Clay and Sam. Our journey started at Maroon Lake, a popular and often crowded destination at the foot of the famous Maroon Bells. This area, to me, is the crown jewel of North America. Named for the maroon color of the crumbly sandstone and the bell-like shape of the twin mountains, the Maroon Bells are picture perfect.
Maroon Lake backed by the famed Maroon Bells. The Four Pass Loop begins here
The Bells have become so popular that it is now required to book reservations ahead of time on the $15 round-trip shuttle from Aspen Highlands to the Maroon Lake parking area. This price has nearly doubled since last year due to social distancing requirements that have emerged due to the Covid-19 pandemic. Backpackers can purchase an overnight parking permit for $10 a night, but permits were all sold out when we tried to purchase them. We ended up parking for $6 a night at the Buttermilk parking lot, taking a free RFTD public bus to Ruby Park where we transferred to another free bus that brought us to Aspen Highlands. There is overnight parking at Aspen Highlands for $25 a night, but we decided that this was not worth the extra money.
Once at Maroon Lake, we stopped briefly to talk to one of the Aspen Center for Environmental Studies (ACES) naturalists who took our photo in front of the lake. I was taken aback when realizing that 15 years had passed since I spent a summer in Aspen as an ACES naturalist. I remembered leading free interpretive nature hikes from Maroon Lake to Crater Lake, teaching children’s programs at the Hallam Lake nature center in Aspen, and enjoying the steepest learning curve of my life under the instruction of Jim Kravitz and his colleagues. It was such a throwback to what I would say was the very best summer of my life.
Describing the natural history of the Golden Eagle (Aquila chrysaetos) while interning as a naturalist at
ACES in 2005
Our hike began by walking along a level stretch of shoreline along Maroon Lake. Angie and I spotted our first lazuli bunting (Passerina amoena), a life-lister that got our trip started off on the right foot. We then filled out a backcountry permit at the USFS permit box just beyond Maroon Lake (9,585 ft) and headed up the 1.8-mile rocky trail to Crater Lake (10,076 ft). I should note that backcountry permits are currently free but there is talk about moving to a paid permit system needing reservations in the summer of 2021.
Along the trail we delighted in seeing some of our first wildflowers of the trip, Rocky Mountain penstemon (Penstemon strictus) and the Colorado state flower blue columbine (Aquilegia coerulea). Thimbleberry (Rubus parviflorus), Wood’s rose (Rosa woodsii), and shrubby cinquefoil (Dasiphora fruticosa) were also in full bloom.
Rocky Mountain penstemon (Penstemon strictus) can be identified by the two lobes on the top part of the flower that hang over the three lobes of the bottom
Thimbleberry (Rubus parviflorus) belongs to the raspberry family. The name refers to the shape of the berry. It is a favorite seasonal food of birds and black bears. Hikers also enjoy snacking on these berries along the trail
The backcountry bums pose for a photo in front of Crater Lake (10,076 ft)
Beyond Crater Lake, we followed the trail in the clockwise direction along the West Maroon Pass Trail. If you are considering attempting the loop and are deciding on which direction to go, I would highly recommend going clockwise. This way, the first day is relatively mellow, approaching 7 miles, stopping just shy of the first pass: West Maroon. It also saves what I would consider the most spectacular scenery of the hike for the last two days. Contrarily, the counter-clockwise direction forces you to immediately ascend Buckskin pass (12,462 ft) with all of your weight on your back. It is also an 8.5-mile hike to Snowmass Lake from Maroon Lake. This is typically where the first camp is made on the counter-clockwise approach.
Ascending the West Maroon Trail, we passed through wet meadows filled with white marsh marigold (Caltha leptosepala), Lewis Flax (Linum lewisii), Virginia strawberry (Fragaria virginiana), owlsclaws (Hymenoxys hoopesii), and wild geranium (Geranium maculatum). Looking back down the valley towards Crater Lake, we noticed several alleys of felled aspen trees where avalanches had plowed down anything in their path. We marveled at the sheer power of nature. Several of these avalanches had formed seemingly barren scree fields Looking more closely, we found that this habitat was filled with life. Dozens of blue columbines (Aquilegia coerulea) poked their spurred heads above the boulders along with Western sweet-vetch (Hedysarum occidentale) and red-berried elder (Sambucus racemosa). We also heard the high-pitched chirps of the American Pika (Ochotona princeps), a cute member related to rabbits (Family: Leporidae; Order: Lagomorpha) that dwells above the tree line in rocky burrows. Despite the harsh winters, the Pika does not hibernate. It survives by feeding on grasses and forbs that it collects throughout the summer and hoards in its burrows.
White marsh marigold (Caltha leptosepala) grows abundantly in the wetter areas along the West Maroon Pass trail
Lewis Flax (Linum lewisii) is one of the more common species growing along the trail. It is named after the explorer and naturalist Meriwether Lewis, who collected the first specimen of this species in the Rocky Mountains
Virginia strawberry (Fragaria virginiana) is one of the many edible species that can be found along the Four Pass Loop. Its berries are much small than the domestic variety but they are often much sweeter. The berries can be harvested in August and September
Blue columbines (Aquilegia coerulea) poke their spurred heads above the boulders along with the pink blossoms of Western sweet-vetch (Hedysarum occidentale)
Red-berried elder (Sambucus racemosa) can be seen growing in scree fields like this one above. Its roots, flowers, foliage and fruits are toxic if ingested raw. The fruits are reportedly edible if they are cooked before consuming
The American Pika (Ochotona princeps) is a denizen of rocky scree fields near and above timberline. They do not hibernate. Instead, they forage herbs and forbs throughout the summer and dry them on the rocks to later hoard them in their burrows for their winter food supply
We were momentarily delayed by our first river crossing that required us to remove our shoes and wade thigh deep through a swift-moving current. We were glad we had purchased hiking poles before the trip. I was uncertain whether or not I would even use the poles. I can affirm that these are an essential item at this time of year, even if used for nothing else but the river crossings. The last thing you want to do on your first day of a backpacking trip is fall into a river and get all of your gear wet. It was nice to have these extra “two feet.”
About four hours into our hike, we found the perfect camping spot in a copse of subalpine fir (Abies lasiocarpa) and Engelmann spruce (Picea engelmannii). There were a number of campsites just off the trail, so we had to hike off the trail a few hundred yards to find some solitude. It’s important to note that camping is prohibited within 100 feet of all water sources and hiking trails and campfires are prohibited within 100 feet of water sources and above 10,800 feet. It is also a requirement to have enough bear cannisters to store all the food for the trip. We encountered forest service rangers that were giving out citations for not storing food in bear cannisters. Hanging a bear bag was not enough. Many of the trees on the loop do not have branches that extend 6 feet from the trunk and if they do, they are likely to be dead and break when forced to bear the weight of your bag. Take this seriously. Bear cannisters do seem like a pain to carry, but they can be packed efficiently and you will be glad you have it when are tired and about to retreat to your tent for the night. Angie even used ours as a makeshift laundry machine to wash our socks with biodegradable soap.
Not long after we assembled our camp, the skies began to darken, thunder rumbled in the distance, and before long a cold, driving rain had us headed for shelter in our tents. Sam had planned on sleeping in his hammock but quickly retreated to Clay’s tent went he somberly realized that his rain fly wasn’t going to keep out the horizontally driving rain.
Our tent at our first night's campsite in the West Maroon valley
The storm passed quickly, as they often do in the mountains, and the skies cleared mercifully. Despite the wet wood, Angie was determined to get a fire started. She spent some time collecting the driest wood she could find and after several frustrating attempts we were ultimately successful in starting a fire.
Angie and I emerged from our tent under a beautiful rainbow
Angie was our fearless wood collector
Bedtime comes early on backpacking trips and so does rising time. We were out of our tents by 6:30 am, awaiting the sun to warm us with its blissful rays. Breaking down camp does not happen quickly and we weren’t leaving the site until around 9:30 am. Our goal was to be hiking by 9:00 am. It is important to be over the high mountain passes before noon in the summer when afternoon thunderstorms roll in like clockwork. One of the greatest dangers in the mountains is being struck by lightning. According to the National Weather Service, on average, 3 people are killed, and 12 are injured by lightning strikes in Colorado every year (9news 2020).
The river closest to our camp in the West Maroon Valley
Group photo at campsite #1
With this in mind, we set out with a pep in our step, heading up towards our first pass: West Maroon (12,490 ft). I was the group’s main impediment to getting over the passes by noon. Of course, I was distracted by the showy displays of wildflowers along the trailside. The bright yellows of alpine false springparsley (Pseudocymopterus montanus) and glacier lily (Erythronium grandiflorum) complemented the white of American bistort (Bistorta bistortoides) and the red and neon green of giant red Indian paintbrush (Castilleja miniata). The gray willow (Salix glauca) carrs were frequented by trilling white-crowned sparrows (Zonotrichia leucophrys) and flitting Wilson’s warblers (Cardellina pusilla), which I often struggled to see through my binoculars.
Glacier lilies (Erythronium grandiflorum) often bloom in areas where the snow has just melted
Giant red Indian paintbrush (Castilleja miniata) is site to behold. All paintbrush species are hemiparasites, meaning that although they can photosynthesize on their own, they often tap into the root systems of neighboring plants to steal nutrient reserves
Vast colonies of white marsh marigold (Caltha leptosepala) and Ross's avens (Geum rossii) blanket the mountainside on the approach to West Maroon Pass
A white-crowned sparrow (Zonotrichia leucophrys) gleans a caterpillar from a branch of a gray willow (Salix glauca)
Cresting West Maroon Pass, we were greeted by a vocal yellow-bellied marmot (Marmota flaviventris) and were overwhelmed with the beauty of the open vista that revealed itself on the other side. The bright verdant green of the valley meadows almost jumped up and hit us in the face. The ridge and the rocky slopes around us were a bright red or maroon in the right light, aptly living up to its name.
Yellow-bellied marmot (Marmota flaviventris) hibernate for nearly half of their lifetime. Known colloquially as "whistle pigs" for their sharp alarm call, these ground squirrels return to their burrows in late September and don't emerge again until late April or early May
The view of the West Maroon Valley from the top of West Maroon Pass (12,490 ft). Note the maroon color of the sandstone, which gives the pass and the Maroon Bells their name
We descended West Maroon along a rocky switchback dotted with the blooms of purple sky pilot (Polemonium eximium) and a solitary Colorado ragwort (Senecio soldanella). As we made our way into lush montane gardens crossed by rippling creeks, we stopped to have a snack and pop an electrolyte tablet to energize us for the ascent to our next pass: Frigid Air (12,415 ft). Some of the more notable wildflowers along this stretch of the hike were hairy valerian (Valeriana edulis), American yellowrocket (Barbarea orthoceras), ballhead waterleaf (Hydrophyllum capitatum), Western roseroot (Rhodolia integrifolia), and Western Indian paintbrush (Castilleja occidentalis).
Sky pilot (Polemonium eximium) is a high alpine species in the Phlox family. Wildflower enthusiasts consider it to be a highly rewarding find
Colorado ragwort (Senecio soldanella) is an easily identifiable species, as no other species looks quite like it. The anthocyanins that create the purple color of the leaves are believed to be an adaptation to protect the plant from the harsh UV rays of the sun that are regularly endured at such high altitudes
Hairy valerian (Valeriana edulis) is also known as tobacco root. Belonging to the family Caprifoliaceae, it is actually more similar to elderberry and honeysuckle than it is to tobacco
American yellowrocket (Barbarea orthoceras) belongs to the mustard family, Brassicaceae. Plants can easily be identified as belonging to the mustards if the flowers have 4 petals, usually in the shape of an "X" or an "H," 4 sepals that are usually green, and 6 stamens: 4 tall and 2 short
Ballhead waterleaf (Hydrophyllum capitatum) can be easily identified due to its flower hanging lower than its leaves. The inflorescence is a tight cluster of flowers with protruding stamens and anthers
Western roseroot (Rhodolia integrifolia), or King's Crown, belongs to the stonecrop family, Crassulaceae. Natives of northern Alaska chew the roots and spit out the juice to ease the discomfort of mouth sores and sore throats
Western Indian paintbrush (Castilleja occidentalis) can be seen growing throughout high alpine meadow. In the autumn, its leafy bracts will turn purple, giving it a distinct bi-colored appearance
About 20 minutes shy of Frigid Air Pass, we encountered a gorgeous colony of alpine sunflower (Hymenoxys grandiflora). This plant is sometimes referred to as the “old man of the mountain” due to a silver-looking pubescence on the stem and leaves. It is a member of the Aster family and is not a true Helianthus sunflower. It differs from true sunflowers by not exhibiting heliotropism, where the face of the flower follows the sun from east to west throughout the day. There is some speculation that this is due to an adaptation to avoid damage from afternoon summer thunderstorms that regularly blow in from the west (National Park Service 2012).
An abundant display of alpine sunflowers (Hymenoxys grandiflora) just before Frigid Air Pass
The approach to Frigid Air was short and steep and before we knew it we were looking down into the Fravert Basin with spectacular views of North Maroon peak in front of us. It was quickly being shrouded by ominous clouds and frigid winds blew in from the same direction. As we did our best to quickly descend the switchbacks from the top of the pass, I stopped to take this picture of a beautiful Parry’s primrose (Primula parryi).
Sam, Clay, and Angie (from left to right) at the top of Frigid Air Pass (12,415 ft)
Angie in her rain gear with North Maroon Peak and the Fravert Basin in the background
Parry’s primrose (Primula parryi) is North America's largest and showiest member of the primrose family (Primulaceae). In contrast to its beauty, it has a rank, skunky odor that can be smelled for years after pressing for collections
Within minutes, the storm moved in on top of us and doused us in driving hail pellets. We stopped to change into our rain jackets and protected our packs with rain covers.
About a mile down the trail, we had descended enough to re-enter the subalpine forest, which provided us a canopy from the continual precipitation. Gradually, the clouds moved off again and rays of sunlight began to peer down into the understory. The flute-like song of a hermit thrush (Catharus guttatus) welcomed the heavenly rays of sun that illuminated dripping evergreen branches. An American three-toed woodpecker (Picoides dorsalis) flew into my view and began chipping sideways and flaking off bark of a dying spruce. Its bright yellow crown made its identification easy, as it is the only woodpecker in Colorado with this field mark. Unlike other woodpeckers, over time this species has lost its fourth toe, perhaps allowing the bird to lean farther away from the tree and deliver stronger blows than other species (Cornell Lab of Ornithology 2019).
Farther down the trail, the forest opened up at the crest of a magnificent waterfall, plummeting down into a montane valley braided in crossing streams. It was at the base of this waterfall in a sheltered grove of spruce where we made our camp for the night. It had taken us a little over 5 hours to reach this spot, 7 miles down the trail from our previous night’s camp spot.
Our second night's campsite (left) with Crystal Falls to the right
Although we did our best to take advantage of the momentary sunshine and set up camp without getting all of our things wet, the clouds rolled back in and doused us with afternoon showers. Before the rains came, Angie was able to wash our dirty clothes and I was able to fish the banks of the Crystal River. The banks were mossy and muddy and covered in one of my favorite wildflowers: elephant’s head lousewort (Pedicularis groenlandica). I caught four small brook trout (Salvelinus fontinalis), all too small to consume (about 6 – 8 inches in length), and released them where they were caught.
Elephant’s head lousewort (Pedicularis groenlandica) is named for the flower that resembles the ears, forehead, and trunk of an elephant
One of four brook trout (Salvelinus fontinalis) I caught on the Crystal River near our campsite
Later, the rain chased us into our tents where we ate our dinner, snuggled in the warmth of our sleeping bags. After the rain blew through, we emerged from our tents to admire a torched sky as the sun sank into the mountains to the west of us. The four of us backcountry bums reunited and set out on the nearly impossible task of starting a campfire with wet spruce wood. We were determined, however, and finally managed to incite a blaze that kept us warm until around 9 pm, when we returned to our tents.
Post-rain sunset near our campsite on the Crystal River in the Fravert Basin
Warming up our feet by the campfire after the rain
The following day, we cleaned up camp and set out on a 6-mile journey towards Snowmass Lake via Trail Rider Pass. This was, in my opinion, the most physically demanding leg of the trip. In the morning, we hiked through mellow rolling meadows alongside the Crystal River. Wildflower blooms stunned the senses around every corner: the pale violet-blue of mountain bluebells (Mertensia ciliata), the white and yellow corolla of heartleaf bittercress (Cardamime cordifolia), purple-brown clusters of Whipple’s penstemon (Penstemon whippleanus), elegant clusters of pretty Jacob’s-ladder (Polemonium pulcherrimum), and a solitary Western red columbine (Aquilegia elegantula) nodding in the dappled light of the understory. A broad-tailed hummingbird (Selasphorus platycercus) dashed in to drink nectar from the drooping flowers of twinberry honeysuckle (Lonicera involucrata).
Group photo at campsite #2
Mountain bluebells (Mertensia ciliata) are one of the more common wildflowers we saw in the understory of subalpine forests
Heartleaf bittercress (Cardamime cordifolia) was growing by the hundreds along the trail along the river in the Fravert Basin. The flowering stalks shoot up from underground runners
Pretty Jacob’s-ladder (Polemonium pulcherrimum) is very abundant in the dry shade of spruce forests. This plant exudes a strong skunk odor when touched
The scarlet bloom of Western red columbine (Aquilegia elegantula) always catches the eye
I stopped to spend some time noticing the remarkable spikes of several monument plants (Frasera speciosa). The flowering spikes of these plants can reach heights of 7 feet! Monument plants have a monocarpic life history, where they can live up to 30 or 40 years without flowering, only to flower in the last season of its life (Colorado’s Wildflowers 2018). This is different from polycarpic biennial and perennial plants that flower each growing season of the plant’s life. I remember these plants growing in abundance near Maroon Lake during the summer of 2005.
A field of flowering monument plants (Frasera speciosa) near Maroon Lake in 2005
Stopping to put our shoes back on after a river crossing forced us to take them off
About 1.5 miles down the trail, we reached a junction where we started our 2,540-foot ascent to Trail Rider Pass. We passed through dreamy stands of quaking aspen (Populus tremuloides) and wound our way up what seemed like endless switchbacks to a small lake where we refilled our camelbacks with filtered water. Rivers flowed in every direction through fields of striking magenta-colored Rhexia-leaf Indian paintbrush (Castilleja rhexifolia). Snowcapped cornices draped the highest peaks.
Quaking aspen (Populus tremuloides) form clonal stands that are interconnected by a singular root system. This is an adaptation that allows this species to grow on steep mountainsides, contributing to soil stabilization
Rhexia-leaf Indian paintbrush (Castilleja rhexifolia) in a meadow of slender cinquefoil (Potentilla gracilis)
Finally, after what seemed like an eternity, we crested the 12,415-foot pass at Trail Rider. Spreading out on the rocks to eat a lunch of canned oyster sandwiches, we drank in sweeping views of Pyramid and North Maroon Peaks to the east and Snowmass Lake to the north. The rest of our day’s hike would be downhill into the glacial cirque that is home to Snowmass Lake. The North face of the mountain still had quite a bit of snow. In places, we traversed rapidly-melting snow bridges and muddy embankments. The hillsides were carpeted with the yellow blooms of Ross’s Avens (Geum rossii) and I stopped to admire the elegant flowers of moss campion (Silene acaulis) and mountain death camas (Anticlea elegans).
Wearing our best miner's faces at the top of Trail Rider Pass (12,415 ft)
Ross's avens (Geum rossii), also known as alpine avens, is one of the most common forbs in the alpine tundra. It turns a burnt orange-red in the autumn, turning entire swaths of tundra into vibrant autumnal landscapes. This plant is one of the favorite forages of American Pikas (Ochotona princeps)
Moss campion (Silene acaulis) occurs in almost all alpine and arctic habitats in the northern hemisphere from as far south as Arizona to as far north as Greenland
Mountain death camas (Anticlea elegans) is a highly toxic plant that caused the deaths of many early pioneers who settled in the mountain west. The plant was often confused for edible species like onion and camas. It is also a known killer of livestock
As we continued onward,