Sourdough Loop (North Cascades)

This past Monday was hot and sunny, and it seemed like a great time to visit the high country in search of views and cooler air. I decided to do the Sourdough Loop, as described on the North Cascades National Park website. This loop wasn’t possible for awhile because the bridge across Diablo Lake was out. But they repaired the bridge this winter, and now you can make a loop by heading up the Sourdough Mountain trail to the Sourdough Lookout, and then dropping down the other side via the Pierce Mountain trail. Eventually the Pierce Mountain trail intersects the Big Beaver Trail, which connects to the Diablo Lake trail and ultimately deposits you back where you started, in the little town of Diablo.

Sourdough Loop: Approx 21 miles and 6300 ft of elev gain

The Sourdough Mountain trail is a steep climb, particularly the first couple miles, but the good news is that it’s currently in great condition. There are zero blowdowns, and the trail is essentially snow-free until the very top, when you hit the ridge. Once on the ridge, there is nearly constant snow. However, I was on the ridge at 900 am on a sunny day and the snow was just about perfect – firm and consolidated but still soft enough that I didn’t need traction.  The views at the top are outstanding, the trail is easy to follow (even when it hits snow), and Sourdough Mountain make a great day hike in and of itself.

Sourdough Camp – there are still some patches of snow, but at least two of the campsites are melted out and ready for use. (I didn’t check beyond the second site.)
Views start just up the trail from Sourdough Camp
Davis on the left
Trails like this make me happy.


Cool view up the Thunder Creek drainage
Still a fair amount of snow on the ridge
Approaching Sourdough Lookout from the west
Happy place

Pierce Mountain trail is a different story. The first mile or so of the Pierce Mountain trail from the Lookout is still buried under snow, but unlike the Sourdough Trail, there is no obvious track. I used a combination of intermittent cairns, a faded set of footprints, and map/GPS to make my way down the east ridge on the Pierce Mountain trail. There were a few steep sections, but the snow was soft enough to plunge-step and the runouts were mostly gentle.

If you say so…
Looking back up at Sourdough Lookout as I descended towards Pierce Mountain Camp


One of the steeper sections  on the Pierce Mountain trail. The run-out was flat and snow-covered, with no rocks or trees. I had trekking poles and trail runners.

At 5400′, the Pierce Mountain trail starts to reappear in places, but it’s not until 4900 ft that it’s completely clear. And by completely clear, I mean clear of snow. Definitely not clear of brush. When I checked my GPS it showed that I was significantly off-route, and the trail was rough enough in places that I briefly wondered if I’d missed a turn. However, I was going in the right direction (down the mountain) and the trail had clearly been maintained at some point, so I stuck with it, and sure enough, eventually I confirmed that I was indeed on Pierce Mountain trail. It’s just not where it’s supposed to be, according to the Earthmate map. Technology – it’ll getcha every time.

The dotted line shows the mapped location of Pierce Mountain trail according to Earthmate (Delorme software). The green arrow was my position, on the actual trail.
Pierce Mountain trail – brushy but passable
Craggy Hozomeen on the left, with Desolation right in front of it.

One of the nice things about this loop is that you get all the hard stuff over at the beginning. There’s 6300 ft of elev gain for the loop, but 5000 of that happens during the first 5 miles up to Sourdough. Even Pierce Mountain ultimately turns into a mellow trail through the woods. Big Beaver and Diablo Lake trails were smooth sailing with minimal blowdowns, no snow, and no route-finding issues.

This little frog made me laugh. As soon as my shadow fell over him, he scurried into the mud and hid… if he can’t see me, he must be safe, right?
Typical Big Beaver trail conditions

One important note… make sure to fill your bottles before you start your descent off Pierce Mountain. The trail is dry as a bone until you hit a small stream just past Ross Lake Resort. I ran this section mid-day, temps in the high 80s, and I was so glad to see that creek near the resort.

The final miles on the Diablo Lake trail are lovely. Shaded, cool, and the perfect end to a run. Unfortunately for me, I had started at the Sourdough trailhead and therefore still had to run a couple miles of road between the Diablo Lake TH and the Sourdough TH.

In hindsight I wish I’d started at the Diablo Lake TH and gotten the road section out of the way first. The road also would’ve made a nice warm-up before you start the steep climb up Sourdough. Which reminds me – you’ll probably want to bring a map that’s detailed enough to show the trails/roads near Ross Dam and Diablo Dam, as things could get a little confusing. I’m sure you could figure it out by wandering around, but why log extra miles on the road when there’s all that trail to explore?

Pyramid Peak as seen from Ross Dam. Just a couple miles to go.
Blueberries in the cooler when I got back to the car. NOM NOM NOM



4 Replies to “Sourdough Loop (North Cascades)”

  1. Great report and glad to see the pics. I’ll have to put this one on my list of to do runs. Keep em coming.

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