Tweedy Mountain

Highest of the East Pioneer Mountains

Tweedy Mountain, 11,154 ft, is the loftiest summit in Montana’s East Pioneer Mountains.

These mountains consist of a granitic core, exposed by uplift and weathering. This is accompanied by a mix of ancient sedimentary and metamorphic rocks that have also been uplifted by plate tectonics.

Glacial activity during the last ice age sculpted the peaks of the mountain range and left behind an impressive number of glacial lakes. South Gorge Lake, North Gorge Lake, and Barb Lake, below Tweedy’s east side, are three of them.

To reach the trailhead for Tweedy Mountain, follow signs for Gorge Lake trailhead once you leave Apex, not a town but a turn off from Interstate Highway 15. Follow an unimproved dirt road to the trailhead. The trail itself, for a short distance, is a dirt road that turns into a well-established track and then becomes a scramble over boulders at the end. There is also a major stream crossing along the trail.

The trailhead provides access to the Gorges Lake and Barb Lake.

Both of these approaches are worthwhile, and the lakes offer good fishing. The Gorge Lakes trail is best in summer, and Barb Lake is possible to reach on skis for a winter ascent.

They are strenuous hikes but enable a climber access to some of the most beautiful lakes in the East Pioneer Mountains.

If you’re planning a round trip in one day, plan for about eight hours. The best guidance for this adventure is to purchase the book Exploring Montana’s Pioneer Mountains by Leroy Friel. It introduces you to many other possibilities in the Pioneers and other ascent lines to climb Tweedy. The USFS map of the Beaverhead-Deerlodge National Forest also clearly shows the route.

The closest town to the summit trail is Dillon, home to the University of Montana Western, as well as lodging and dining options.