Commonwealth Basin

Ascending 900 feet and traveling 5 miles round trip, this is a longer alternative to the Commonwealth Falls route.


From the I-90 take exit 52.  Park at the Summit West lot, carefully crossing the summit access road and walking under the highway overpass to reach the trailhead on the north side of the I-90.  Don't be tempted to park at the cleared area at the top of NF-58 (the old Snoqualmie Pass Road).  Despite appearances, that is a no parking area.


The trailhead begins on the north side of Interstate 90 at the northbound PCT trailhead.  Travel along Commonwealth Creek beyond Commonwealth Falls, heading up into where Commonwealth Basin opens up to views of Red Mountain and Lundin Peak.

Information FOr leaders

scheduling & Permits

  • As of 2017, the Snoqualmie Ranger District considers Mountaineers trips and courses to be "nominal use". Leaders should print and copy this designation letter to show rangers they may see on trail or carry a digital copy on their phone.
  • If you are scheduling this as a non-course related activity, please limit your group size to the recommended party size. The maximum party size is for use by course field trips only, and includes both students and instructors. Group size maximums do not reflect how course field trips are run (in smaller groups of students and instructors), but allow for course leaders to register the course in our system.
  • Please note that this trail enters the Alpine Lakes Wilderness, and trips proceeding into the Wilderness must comply with wilderness regulations. Groups exceeding 12 must divide into physically and logistically separate parties and maintain a minimum distance of one-mile separation. 
  • If you are scheduling a course field trip, please contact our Member Services Team to confirm the field trip and any permitting regulations.
  • Difficulty: Moderate
  • Length: 5.0 mi
  • Elevation Gain: 900 ft
  • 3,900 ft
  • Land Manager: Mount Baker-Snoqualmie National Forest
    Alpine Lakes Wilderness, Snoqualmie Ranger District (MBSNF)
  • Parking Permit Required: None
  • Recommended Party Size: 12
  • Maximum Party Size: 24
  • Maximum Route/Place Capacity: 24
  • Green Trails Snoqualmie Pass Gateway No. 207S
  • Green Trails Snoqualmie Pass No. 207
  • USGS Snoqualmie Pass

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