Sacajawea Hot Springs
Sacajawea Hot Springs blasts out at 153 degrees Fahrenheit at 5,000 feet elevation in the Boise National Forest, making it dangerously hot at the source. The spring sits just 135 feet from Grandjean Road, where its steam is impossible to miss even from a moving vehicle.
The setting is classic central Idaho mountain forest near the South Fork Payette River headwaters, east of Idaho City. Annual snowfall averages over 15 feet, and the air temperature averages 43 degrees, creating a 110-degree gap between the water and the surrounding environment. The canyon holds the smell of sulfur and wet granite. Downstream from the source, the scalding water mixes with cold creek flow, and it is in these mixing zones that temperatures become tolerable for soaking.
The 153-degree source temperature and the enormous thermal differential indicate deep fault-guided circulation, likely to depths exceeding a mile beneath the surface. The Grandjean area sits at the edge of the Idaho Batholith where granitic rocks have stored residual heat for millions of years. Bonneville Campground, 11 miles west, offers access to similar geology and its own hot springs along Warm Springs Creek.
Do not touch the source water. At 153 degrees, contact causes immediate burns. Soaking is only possible downstream where cold water mixes in, and temperatures vary unpredictably. The spring is roadside on Grandjean Road, east of Lowman. Bonneville Campground, about 11 miles away, is reservable and has its own nearby hot springs. Roads close with snow, typically November through June.
Is Sacajawea Hot Springs worth visiting?
Best for
- Observing powerful hot springs
- Easy day trips
- Overnight camping trips
Not ideal for
- Casual soaking
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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...