So. Many. Alternates.

I’m thinking about hiking the CDT this year, and I’ll probably be going SOBO. It all comes down to Colorado. The state’s snowfall is currently about 140% of normal, and the San Juans have almost 180%. Starting northbound in April would virtually guarantee spending a lot of time trudging through snow. Instead, if I wait until June to head south, there’s a good chance I can still clear Colorado before the first big storms of next winter.

In my experience, it doesn’t need to be end-of-season for weather on the continental divide to turn nasty. Of the four occasions I’ve hiked short sections of the trail, I’ve been caught in a blizzard twice. The first time was a thunder/snow/hailstorm while crossing Pitamakan Pass in Glacier National Park. The second time, in the Wind River Range, I spent an afternoon in white-out conditions, wondering if winter had arrived early. On both occasions, it was late August.

Knapsack Col

This is where I experienced those white-out conditions. Leaving the CDT going north, the trail loops around the southeastern shore of Island Lake, and heads north into Titcomb Basin. After Titcomb Lakes, the trail disappears among the rocks, and you’re on your own. Jonathan Ley’s “Old CDT” track is the first to turn west and begin the climb. Bear Creek Survey’s alternate waits until the last minute to head west. I climbed somewhere between the two, skirting the northern edge of the remains of Twins Glacier. Whichever route you take, it’s steep, rocky, and risky if there’s still a lot of snow.

At the top, you’re looking down at the source of the Green River to the west. The descent is easy compared to the climb, and you’ll be back on trail in no time.

Patches of snow and ice in rocky, Alpine surroundings.

Twins Glacier, from Knapsack Col.

Cirque of the Towers

Another of Wyoming’s CDT alternates starts (for a NOBO) at Little Sandy Lake. I started at the Big Sandy Trailhead, and joined the alternate at Big Sandy Lake. Just beyond North Lake, the main trail heads uphill to the right, and there’s a sign pointing to the “climber’s route” on the left. I took the left-hand route, a detour of less than a mile that follows the western shore of Arrowhead Lake. You’ll scramble over car-sized boulders before the trail resumes for the climb to Jackass Pass.

At the top, the mountains welcome you into their semi-circular huddle, but your job is only half done. There’s a 600 foot descent to Lonesome Lake, and a 1200 foot climb to Texas Pass. The descent after that is steep and slippery at first, even when there’s no lingering snow.

Fluffy clouds, an Alpine cirque and a subalpine lake.

Cirque of the Towers, from Jackass Pass.

Some resources

It’s understandable why the alternates I’ve just described are so popular with CDT hikers. Not only are they spectacular, but they’re not far from the trail and have little influence on a thru-hiker’s resupply strategy. However, there are plenty of other places where deviating from the official route will affect where I resupply. I decided to investigate the alternates before planning further. Here are my top-three results.

  1. A 2019 post by Trek blogger “Sourstraws”. She provides pictures and summaries of the major alternates. She also describes the most popular navigation resources, including those from Bear Creek Survey and Jonathan Ley.
  2. When ‘Straws wrote her article, Bear Creek Survey didn’t have a mapbook for the alternates. Today, from the Bear Creek homepage, if you click on a link for any of the other CDT mapbooks, you’ll also see one called “CDT Alternates 2020”. I’ll be using my phone for navigation, with my Garmin as backup, and the Bear Creek website has a set of files I can use. More on those in a moment.
  3. I’ll be using the Farout and Avenza apps, and I’ve downloaded the Avenza maps from the Continental Divide Trail Coalition and from Jonathan Ley. On Jonathan’s website, I also found a KMZ file from about 15 years ago which contains CDT coordinates and a handful of short alternates in Montana. More on this file in a moment too.

Popular CDT alternates. (Mileages from Bear Creek’s data.)

Let’s get technical

My Garmin GPSMAP 64 has limits related to GPX files and their contents.

  • 5,000 waypoints
  • 200 routes, 250 points per route
  • 200 saved tracks, 10,000 points per track

Bear Creek Survey’s website allows you to download a set of approximately 8,800 waypoints for the CDT in point-of-interest format. Points of interest aren’t subject to the above constraints, but they have limited display options on the GPSMAP 64. As a result, I prefer the GPX version of the waypoint data, which Bear Creek has also made available. By separating the mile-markers from other waypoints, I was able to meet Garmin’s specifications.

I also simplified Jonathan Ley’s old CDT coordinates into a track containing fewer than 10,000 points. This version of the “Old CDT” is a potential source of alternates, especially if I find myself falling behind schedule. It’s about 2572 miles long, compared to today’s CDT of 3129 miles.

I’ve checked all of the files on my GPSMAP 64, and I’ll be taking them with me on the CDT. Maybe they’re of some use to you, even if you only use them in Google Earth to help plan your hike.

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