Sacajawea Hot Springs

What to expect

Sacajawea Hot Springs is not one pool but a loose chain of them, scattered along roughly 0.2 miles of the north bank of the South Fork Payette River near Grandjean. Hot water seeps and spills out of the bank between Grandjean Road and the river, and soakers have walled off pockets of it with river rock, sand and gravel. How many pools there are depends on the year. Visitor logs have counted three usable pools on one visit and seven on another.

The water at the source is very hot, reported at anywhere from 125 to 160°F52 to 71°C. You cannot soak in that. The pools that work are the ones where the river leaks in and cools things down, so the temperature changes with the river level, the time of year and which rock someone moved last. Expect hot and cold streaks in the same pool. Stirring the water with your hands evens it out. The water is clear, with at most a faint sulfur smell.

The setting is a forested river valley with the Sawtooth Mountains close by to the east. Grandjean Peak shows up in a 1916 photograph of “Sacajawea Hot Springs on the Payette River” held by the Idaho State Archives, so the springs have carried this name for over a century.

There are no facilities at the pools. No toilets, no trash cans, no changing area.

Getting there

The springs are along Grandjean Road (Forest Road 524), a side road off Idaho Highway 21 between Lowman and Stanley.

• From Lowman: Drive northeast on Highway 21 for about 21 miles. Turn right onto Grandjean Road, following signs for the chain-up area. Continue about 5.2 miles. The pools are below the road on the right, along the river.
• From Stanley: Take Highway 21 west and then south about 35 miles to the same Grandjean turnoff, then follow the road east.
• From Boise: Take Highway 21 through Idaho City to Lowman, then continue as above.

Grandjean Road is a Forest Service road that any car can handle in summer when it is dry. There is no real parking lot at the springs. Use the roadside turnouts along the stretch where the pools are, keep your wheels off the road, and walk the short distance down the bank. The bank is steep in places.

If you reach the Sawtooth Lodge, you have gone about half a mile too far. Grandjean Campground is 1.8 miles past the springs.

When to go

Late summer through fall is the window. The South Fork Payette carries heavy snowmelt in spring, and during runoff, usually April through June, the river covers every pool. A visit in mid-May 2007 found them all under water. By July the river is dropping, and people start rebuilding the pools. Late July into October is the most reliable time.

Winter is a different trip. Grandjean Road is closed to normal traffic in winter, and visitors come in by snowmobile, skis or snowshoes. When you can get there, the steam over the river is worth the effort, but plan for cold, deep snow and no services.

Expect company in summer. This is a popular stop for people heading to the Grandjean trailhead and campground.

Before you go, check the Boise National Forest and Sawtooth National Forest alerts pages for fire closures and road orders.

Rules and etiquette

The springs sit right on the boundary between two national forests. Forest Service maps show the pools straddling the line between the Boise National Forest’s Lowman Ranger District and the Sawtooth National Recreation Area. That matters for two rules:

• Swimsuits. A Boise National Forest order (0402-00-64) prohibits public nudity on all Boise National Forest land from August 27, 2025, through August 27, 2030. On the Sawtooth side, Sawtooth National Forest order 0414-00-033 bans public nudity from September 9, 2026 to September 9, 2031, so the rule is the same on either side of the line. The pools are also in full view of the road. Wear a suit.
• No camping by the road. Another Boise National Forest order bans camping within a quarter mile of each side of Grandjean Road on the Lowman Ranger District, except at sites marked with a camping symbol, through June 12, 2030. Camping at the springs themselves is not allowed.

The usual hot spring rules apply too:

• No soap or shampoo, biodegradable or not. These pools have no drains and the river carries anything you add downstream.
• Pack out everything, including food scraps and toilet paper.
• No glass near the pools or in the river.
• Share. If the best pool is busy, help build another one rather than crowding in.

There is no fee.

Where to stay nearby

• Grandjean Campground is 1.8 miles up the road at the edge of the Sawtooth Wilderness. It has 31 first-come, first-served sites in old-growth ponderosa pine, with drinking water, vault toilets and picnic tables, but no trash service. It usually closes around September 21. Sawtooth NRA rules limit stays to 10 days in any 30-day period.
• Sawtooth Lodge, about half a mile past the springs, has cabins, yurts, a few RV spots and a restaurant in season. Its geothermal swimming pool and soaking tanks are fed by hot spring water from the same area, and it is the easy option if the river pools are flooded.
• Bonneville Hot Springs, back west on Highway 21, has a Forest Service campground right by the springs.
• Lowman has a few lodges and cabins, and Stanley has more.

Safety notes

• Scalding water: The source and the uppermost edges of the pools can be hot enough to burn. Test with a hand and keep children close.
• The river: The South Fork Payette is cold and fast, even in summer. Do not let kids wander from the pools into the main current.
• Footing: The bank from the road is steep and loose in spots, and the river rocks are slick.
• Water quality: Keep your head above the water. Warm spring water can carry harmful organisms.
• Wildlife: Deer and elk are common along this road. Bull trout live in the river, so do not dam the main channel or dig into the riverbed.
• No signal: There is usually no cell service along Grandjean Road. Tell someone your plans.

Nearby stops worth adding

The Grandjean trailhead, past the campground, is the western gateway into the Sawtooth Wilderness, with trails up the South Fork Payette and its side canyons. Back on Highway 21, the drive between Lowman and Stanley passes several more hot springs, including Bonneville, and climbs over Banner Summit toward the Sawtooth Valley.