Slate Creek Hot Spring
Slate Creek Hot Spring surfaces at 122 degrees Fahrenheit at 7,020 feet in the Challis National Forest — one of the highest-elevation accessible thermal springs in Idaho. USGS analysis shows 352 mg/L total dissolved solids, 81 mg/L sulfate, and 270 micrograms per liter of iron, giving the water a distinct mineral signature.
A short walk of roughly a quarter mile from the nearest forest road leads to the spring, which emerges in high mountain terrain where average annual air temperature is just 37 degrees. Custer County's rugged landscape stretches in every direction — bare ridgelines, scattered subalpine fir, and wide sky. The iron-bearing water stains surrounding rock in rust and ochre tones. Over 100 inches of snow falls here annually, and the spring steams steadily through the cold months.
The spring rises along fault lines in the Challis Volcanic Group, where ancient volcanic activity created fractured pathways for deep groundwater circulation. The elevated sulfate and iron concentrations distinguish it from the cleaner sodium-dominant springs elsewhere in central Idaho, suggesting contact with mineralized volcanic deposits. The area's mining history, visible in nearby ghost towns, followed the same mineral-rich geology.
Access requires a short walk from the road, making this more accessible than many backcountry springs despite its high elevation. Water at the source needs cooling before contact. Pole Flat Campground is 17 km away with vault toilets and drinking water, no reservations needed. The iron content may stain clothing and skin temporarily. Road access is typically open July through September.
Is Slate Creek Hot Spring worth visiting?
Best for
- Hot spring soaking
- Overnight camping trips
- Winter soaking with dramatic temperature contrast
The water at Slate Creek Hot Spring is alkaline (pH 8.8) with 352 mg/L total dissolved solids.
This campground is away from the main road and up the hill overlooking the river and the dredge ponds. Campsites include picnic tables tent pads fire rings with cooking grills. Campground amenities include a vault toilet and drinking water. Sites accommodate trailers and motorhomes up to 32 feet long.