Bonneville Hot Springs

What to expect

Bonneville is a busy, easy-to-reach soak on the Ponderosa Pine Scenic Byway. The hot water comes out of the hillside above Warm Springs Creek and runs down the slope in small channels. Over the years, visitors have stacked rocks into a series of soaking pools along that runoff, from shallow bathtub-sized pools to a larger main pool. The bottoms are sand and silt. One pool sits below a small waterfall of spring water.

The feature most people remember is the soak shack: a small wooden bathhouse with a cast-iron bathtub inside. Hot water is piped straight to the tub and you plug the drain with a wooden stopper. The walls are covered in carvings from decades of visitors. It is a private soak for one or two people, which makes it popular, so expect to wait your turn on busy days.

Because the pools are hand-built, there is no fixed temperature. The water near the source is very hot, and pools farther from it are cooler, so you move around until you find one that suits you. Rock walls shift, so what was a perfect pool last month may be lukewarm now. Test every pool with your hand before you get in.

There are no facilities at the springs themselves. The campground below has vault toilets, drinking water and trash collection when it is open.

Getting there

Bonneville Campground is just off Idaho Highway 21 at about milepost 91.5, roughly 19 miles east of Lowman.

• From Boise: Take Highway 55 north to Banks. Turn east onto the Banks-Lowman Highway (Highway 17) and follow the South Fork Payette River to Lowman. In Lowman, turn left onto Highway 21 toward Stanley and continue about 19 miles to the signed Bonneville turnoff. You can also take Highway 21 the whole way from Boise through Idaho City, which joins the same road at Lowman.
• From Stanley: Take Highway 21 west over Banner Summit and down toward Lowman. The Bonneville turnoff comes after the Grandjean junction.

Both routes are paved to the campground. Inside the campground, the trailhead is at the northwest end and is signed. The trail follows Warm Springs Creek for about a quarter mile. It is mostly level and well worn, but hot runoff crosses it in places and the ground there is muddy and scalding.

When the campground is closed for the season, use the Warm Springs Trailhead, a small lot just before the Bonneville turnoff, and walk in. That adds about a mile. Snowshoes or skis help once snow sets in.

When to go

Summer is peak season. From about May to September the campground has a host, the sites are often full, and the springs see heavy use. Midday on a summer weekend you may be sharing every pool.

September and October are the sweet spot. Nights are cold, days are clear, and most of the summer traffic has gone. The campground typically closes in October or November, depending on weather.

Winter is quiet and much more work. The campground is gated, so you walk in from the Warm Springs Trailhead. Highway 21 is a mountain road and can be slow or closed during storms, so check the Idaho Transportation Department’s 511 road report before you go.

Spring depends on snow. The campground usually opens in mid to late April or in May. Warm Springs Creek runs high and cold during runoff.

Rules and etiquette

• Fees: Non-campers pay a $5 day-use fee during the open season. Extra vehicles at a campsite are $5 each, with a limit of two vehicles at single sites and four at the double site.
• Swimsuits are required. A Boise National Forest order prohibits public nudity on all national forest land in the forest from August 27, 2025, through August 27, 2030.
• Camping only where marked. Another forest order bans camping within a quarter mile of Highway 21 on the Lowman Ranger District except at sites marked with a camping symbol. Bonneville Campground is the legal place to stay.
• Share the bathhouse. Keep your time in the tub reasonable when people are waiting outside.
• No soap or shampoo in the pools, and no glass on the trail or around the pools.
• Firewood: Buy it locally and burn it on site.
• Pack out trash. Bins are in the campground, not at the springs.

Where to stay nearby

• Bonneville Campground is right at the trailhead. It has 22 sites, including four tent-only sites and one double site, each with a picnic table and fire ring. There are vault toilets, drinking water and a campground host, but no hookups. Sites are reservable on Recreation.gov, and holiday weekends need a three-night stay.
• Other Forest Service campgrounds line Highway 21 between Lowman and the Grandjean turnoff. Several sit near other hot springs.
• Lowman, about 19 miles west, has a few lodging and food options. Idaho City and Stanley are the nearest towns with more choice.

Because camping is restricted to marked sites within a quarter mile of Highway 21 in this district, do not plan on pulling off at a random spot along the highway for the night.

Safety notes

• Scalding runoff: The water near the source and in the channels that cross the trail is far too hot to touch. Keep children and dogs on the trail and away from those channels. This is the main reason the springs are not a good bet for small children.
• Pool temperature: Every pool is different. Test with your hand, keep soaks short and get out if you feel dizzy. Do not put your head under the water.
• Footing: Rocks around the pools are slick and the trail is muddy where hot water crosses it. Wear shoes with grip and take them off at the pool edge.
• Winter travel: Highway 21 is a mountain highway with storms, ice and occasional closures. Carry chains, warm clothes and a headlamp, and expect no cell signal.
• Wildlife: Deer and elk wander through the campground. Store food properly.

Nearby stops worth adding

Highway 21 between Lowman and Grandjean has several more soaks. Kirkham Hot Springs is closer to Lowman, with pools and hot waterfalls on the South Fork Payette right by the road. Sacajawea Hot Springs sits on the river a little farther east, near the Grandjean turnoff. The South Fork Payette across the highway is also popular for whitewater rafting, kayaking and trout fishing.