Potosi Hot Springs
Potosi Hot Springs flows at 122°F at 6,069 feet elevation in Madison County, Montana, making it one of the higher-elevation thermal sources in the state. The alkaline water registers pH 8.3 with 88 mg/L sodium and 98 mg/L sulfate, while calcium and magnesium are minimal. The spring sits just 17 meters from Willow Meadow Road with roadside access near Virginia City.
The spring emerges in the Tobacco Root Mountains at 6,069 feet, where subalpine meadows and dense conifer forests cover steep terrain above the Madison Valley. Annual precipitation reaches nearly 26 inches with about 65 inches of snow, and the average annual air temperature is just 38.8°F, among the coldest settings for Montana thermal springs. Willow-lined meadows occupy the drainage bottoms, giving the road its name. The surrounding country is rugged and sparsely populated.
The Potosi name references the mining legacy of Madison County, echoing the famous Potosi silver mines of Bolivia, a naming convention common in 19th-century Western mining districts. Virginia City, the nearest town, served as Montana's territorial capital during the 1860s gold rush. The spring's proximity to these historic mining camps suggests it was known to early prospectors and settlers working the Alder Gulch placer deposits.
The 6,069-foot elevation means cool temperatures year-round, with an average of 38.8°F annually. Snow closes many area roads by late fall; confirm Willow Meadow Road is passable before driving in. The 122°F source water requires caution. Red Mountain Campground on the lower Madison River, reservable May through mid-September, sits about 26 km away. Virginia City's preserved ghost-town buildings make a worthwhile side trip.
Is Potosi Hot Springs worth visiting?
Best for
- Hot spring soaking
- Easy day trips
- Overnight camping trips
- Winter soaking with dramatic temperature contrast
The water at Potosi Hot Springs is slightly alkaline (pH 8.3).
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Overview The Dillon Field Office is unable to make reservations for you. Please call Recreation.gov (877-444-6777) to book a reservation or book online. Campsites are available for reservation for the Peak-Season times of May 1st through September 15th. From September 16th through April 30th, all sites are first-come-first-serve. Red Mountain Campground is adjacent to the lower Madison River and provides good access for camping, fishing and floating. The campground has 19 camp sites, 11 ava...