Upper Potosi Hot Springs

Harrison, Montana 59735

Upper Potosi Hot Springs

Upper Potosi Hot Springs Professional Review and Guide

"Two primitive high-country hot springs pools with outstanding views of the surrounding Tobacco Root Mountains. This is one of the few hot springs in Montana on public land. The two primitive soaking pools and the great view of the surrounding mountains make Upper Potosi well worth the easy hike. Surrounding the pools is a lodgepole pine fence built to exclude the cattle that occasionally graze in the creekbed surrounds the pools.

You’ll need to climb over or through the fence to reach the hot water. The kidney-shaped upper soaking pool is about 6 feet by 10 feet and comfortably holds three or four bathers. The hot water enters from the uphill side of the pool and from seeps in the pool’s bottom. Two to three gallons per minute of hot water flow through a plastic pipe from the upper to the lower pool. The smaller lower pool can host one or two soakers. Water temperatures in the pools vary from 104 to 110 degrees F. Swimsuits are optional. Primitive."

Upper Potosi Hot Springs Reviews

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Upper Potosi is a really nice example of a bucolic primitive hot spring. It is a rock-formed hollow about 7x12 feet, water about 104 average, hotter in some upwellings and cooler in others. A cool spring drips into the hill side of the pool through rocks and wild flowers. There's a silky sediment bottom; don’t call it mud. The prior directions are a bit incorrect. Here is the corrected last paragraph of the directions to get to the spring: Follow the road toward the Potosi Creek Campground, but turn left when you see the sign “South Loop.” Do not follow the sign that says “Upper Loop, to Potosi Campground.” Turning left, you should continue straight across a small bridge, then slowly drive straight through the shallow ford and park to the left on the loop. The gate to the southeast marks the entry to the easily discernible Forest Trail 308 to the hotspring a mile down the valley. The hillside spring is in a lodgepole pine enclosure downhill to the left at a point 50 feet after the trail has climbed a small hill. (This is a set of directions to the upper hillside spring; we did not find a second hotspring closer to the creek, if there is one. Across the creek, out of sight of the primitive spring, a private lodge has been built around another hotspring.)
There is no longer a second pool as described in the trail guide. Late June of 2007, I visited the spring when there was an upper pool and a smaller lower pool just below it. The smaller pool was too small for a single adult and the larger pool was not much more than a foot deep to where you had to lay down for a worthy soak. But the pools had a nice rustic feel about them due to lack of human maintenance for many years. I revisited the Potosi Hot Spring about 5 weeks later to find that some industrious folks (Potosi camp host?) had completely re-dug a deeper pool and re-did a lot of the rocks, drainage, fencing, the whole works, including the destruction of the lower "pool." At the time, it was unwelcomed due to all of the suspended sediment in the water. But in the long run, it was much needed and I'm sure it provided for better soaks in years since. Look forward to getting back someday!

Upper Potosi Hot Springs Photos

Trail Information

Nearby City
Summer and early fall
Hot Springs
Beaverhead National Forest
Local Contacts
Montana State Highways Map; USGS Harrison
Local Maps

Activity Feed

Jul 2018