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Commonwealth Basin Trail

Snoqualmie National Forest, Washington · 3 min read

Distance
10 mi
Elevation Gain
2,800 ft
Difficulty
strenuous
Route Type
Out-And-Back
Best Season
July through October
Est. Time
6-8 hours
Dog Friendly
No
Kid Friendly
No
Difficulty Score
10 / 10

Trailhead Amenities

Restroom
Vault Toilet
Parking
Fee Required
Cell Service
Good Signal
Water
Nearby
Camping
Dispersed
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Conditions, regulations, and fees change frequently. Verify with the local ranger district before your trip. Full disclaimer

At a Glance

  • High alpine basin with a lake below Kendall Peak
  • Above-treeline views across the Alpine Lakes Wilderness
  • Summer wildflower meadows in the basin
  • Kendall Katwalk nearby for an optional exposed ridge traverse
  • Access to the Pacific Crest Trail corridor
lakeviewsalpine meadow

Commonwealth Basin in Snoqualmie National Forest provides access to one of the finer high alpine basins near Snoqualmie Pass, climbing 2,800 feet to a lake below Kendall Peak and the Pacific Crest Trail corridor. The ten-mile round trip is strenuous but delivers the full Alpine Lakes Wilderness experience: above-treeline meadows, mountain lake, and Cascade peak views.

The trail begins at the PCT corridor near Snoqualmie Pass and heads into the wilderness, making it one of the more direct access points to the Alpine Lakes interior from the I-90 corridor.

The Route

The trail begins at the PCT trailhead and follows Commonwealth Creek upstream through dense Northwest forest. Above treeline at approximately 4,500 feet, the basin opens dramatically with views of Kendall Peak and surrounding summits. The lake sits at the base of the basin headwall and is reached at approximately 4.5 miles.

The PCT and the Kendall Katwalk are reachable on a spur from the basin, adding a second attraction for hikers who want a longer day.

What to Expect

Dogs are not allowed. This is firmly enforced in the Alpine Lakes Wilderness.

Summer wildflowers in the basin are excellent from mid-July through August. The basin receives heavy use given its proximity to the I-90 corridor; weekday visits provide a substantially quieter experience than weekends.

The upper trail can be snow-covered well into July in heavy snow years. Microspikes may be useful on early-season visits.

Nearby

Snoqualmie Pass is directly at the trailhead with limited services. North Bend provides full services about 20 miles west on I-90. Seattle is approximately 50 miles west, making this one of the primary wilderness destinations for the Seattle metropolitan area.

Leave No Trace

This trail receives enough use that following Leave No Trace principles is important for preserving the experience for future visitors. Stay on the marked trail to prevent erosion. Pack out all waste. Avoid camping within 200 feet of water sources or the trail. Use existing fire rings only where campfires are permitted, and check current fire restrictions at checking conditions before you go before any visit. The trail and surrounding terrain remain in good condition because previous visitors have respected these norms.

Safety Considerations

The strenuous rating reflects the trail's general character under typical conditions. Weather, seasonal snow, and trail conditions can change the experience significantly. Carry the 10 Essentials on any full-day outing. Inform someone of your plans and expected return time before heading out, particularly on longer or more remote trails. Cell service varies throughout Snoqualmie National Forest and may be unreliable in canyon bottoms or remote terrain.

Trailhead Parking

Commonwealth Creek Trailhead off I-90 at Snoqualmie Pass. Paved lot; Northwest Forest Pass required as of 2026.

← Back to Snoqualmie National Forest

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Frequently Asked Questions

Is a permit required?
Yes. A Recreation Pass is required for trailhead parking as of 2026. Dogs are not permitted in the Alpine Lakes Wilderness. Verify current requirements with the Snoqualmie Ranger District.
What is the Kendall Katwalk?
The Kendall Katwalk is a PCT section about 1 mile beyond the Commonwealth Basin junction where the trail crosses a narrow ledge blasted into a cliff face. It is not on the Commonwealth Basin route itself but is accessible for those who want to add it.
When does Commonwealth Basin open in summer?
The high basin is typically accessible from mid-July. Heavy snow years may push this to late July. Check conditions with the Snoqualmie Ranger District.
Are dogs allowed?
No. Dogs are not permitted in the Alpine Lakes Wilderness.