Bonneville Hot Springs
Bonneville Hot Springs pushes 185-degree Fahrenheit water from the earth in the Boise National Forest, feeding constructed soaking pools a quarter mile downhill at Bonneville Campground. USGS data records the source at 88 degrees Celsius with a pH of 9.3, among the hottest and most alkaline springs in the state. The campground-to-spring trail makes this a rare walk-in soaking experience.
The spring emerges at 4,880 feet elevation on a forested slope above Warm Springs Creek in Boise County. The trail from Bonneville Campground climbs through mixed conifer forest, with the sound of the creek below. Annual snowfall exceeds 176 inches, burying the area in winter but feeding lush summer vegetation. The soaking pools are rock-and-log constructions where the superheated source water has cooled enough for bathing. Steam rises through the trees on cool mornings.
Bonneville Hot Springs sits along the same fault system that produces several other thermal features between Lowman and Idaho City. The water chemistry, with 77 mg/L sodium and negligible calcium and magnesium, mirrors the deep granitic circulation pattern seen throughout the Idaho Batholith. Sulfate levels at 50 mg/L are higher than neighboring springs, suggesting the water passes through a zone of sulfide mineralization before reaching the surface.
Bonneville Campground, 19 miles east of Lowman off Highway 21, is reservable and sits just a third of a mile from the springs. The quarter-mile trail gains modest elevation. Source water is dangerously hot, so soak only in downstream pools where temperatures have dropped to comfortable levels. Warm Springs Creek nearby offers trout fishing. Winter access depends on road conditions along Highway 21.
Is Bonneville Hot Springs worth visiting?
Best for
- Observing powerful hot springs
- Overnight camping trips
Not ideal for
- Casual soaking
The water at Bonneville Hot Springs is alkaline (pH 9.3).
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Overview Bonneville Campground is 19 miles east of Lowman, Idaho just off Highway 21 at an elevation of 4,700 feet. Warm Springs Creek runs alongside the campground and the South Fork Payette River lies across the highway. Visitors enjoy soaking at Bonneville Hot Springs a short distance above the campground, and fishing in the creek and river.Recreation A 1/4-mile hiking trail leads from the campground to Bonneville Hot Springs, where a soaking pool awaits. Warm Springs Creek offers good tro...