Trail Flat Hot Springs

Trail Flat Hot Springs is a small, undeveloped soak at the edge of the Middle Fork of the Salmon River, at Trail Flat camp in the Frank Church River of No Return Wilderness. It is the first hot spring on the river below the Boundary Creek launch, and for a lot of Middle Fork trips it is the first night’s soak: a rock-walled pool on the gravel bar just below the camp bench, close enough to hear the river running past it. The Forest Service’s river guide states the terms plainly: the spring “is washed out at high water, but is usable at lower water.”

Everything about Trail Flat follows from that sentence. Come during spring runoff and there is no spring to find, just river.

Come from mid summer on, as the flows drop, and the pool emerges at the waterline, clear and hot, rebuilt by the river and by the hands of the parties who camp here.

Soak Stats

Location	Left bank of the Middle Fork of the Salmon River at Trail Flat camp (river mile 6.9), at the river’s edge below the camp bench, Frank Church River of No Return Wilderness, Valley County
Coordinates	About 44.609, -115.269 (published point for Trail Flat camp; the spring is at the water’s edge immediately below the bench)
Soak type	Undeveloped natural spring: one main rock-walled pool on the gravel bar at the waterline, sometimes with smaller satellite pools
Water temperature	No inventoried figure in the sources consulted. The pool is fed by the spring and rimmed by the river, so its temperature follows the river level; test it before you settle in
Access	Permitted float trip on the Middle Fork, or the Middle Fork Trail from Boundary Creek (about 7 miles). No road access
Season	Mid summer into fall, as river flows drop. At high water, including all of spring runoff, the river covers the spring completely
Fee	No fee for the spring. Floating the Middle Fork costs a $4 per person per day recreation fee, plus a $6 lottery or reservation application fee in season
Reservations	A Forest Service float permit is required year-round. Control season launches (May 28 to Sep 3) are allocated by the Four Rivers Lottery on Recreation.gov
Clothing policy	Swimsuits required: Forest Service rules for the permitted river corridor prohibit public nudity
Facilities	None. Trail Flat is an undeveloped assigned river camp on a large rocky bench, and everything, including the portable toilet and fire pan every permitted group must carry, comes by boat or backpack

Place Information

Address	No street address. The spring is on the Middle Fork of the Salmon River at Trail Flat camp, river mile 6.9 measured from the Boundary Creek launch (outfitter guides mark the spring itself at mile 7.3)
County	Valley County
Land manager	U.S. Forest Service, Salmon-Challis National Forest, Middle Fork Ranger District
Website	Recreation.gov: Middle Fork of the Salmon River (4 Rivers) permits

Location, Map & Directions

There are no driving directions to give. Float trips launch at Boundary Creek, below Dagger Falls, and river miles are counted from there. Trail Flat camp is on the left bank at mile 6.9, a large rocky bench that will accommodate a large party, in the Forest Service guide’s words. The spring is at the river’s edge below the bench: one well known trip account describes it as “just below the bank we camped on,” and the photograph at the top of this listing, taken from the camp, shows the pool sitting on the gravel bar with the river beyond it.

There is no reliable eddy at the spring itself, so boaters who are not camped here should be ready to catch the bank decisively.

On foot, the Middle Fork Trail follows the river from the Boundary Creek trailhead and reaches the camp at roughly 7 miles. Camps on this stretch are assigned to each party at launch, and a soak stop does not require the camp to be yours for the night.

The Soaking Experience

What is here, when the river allows it, is one main pool ringed with rocks right at the waterline, fed by the spring and trimmed by the river itself, with smaller satellite pools appearing in some seasons as the bar dries. The water runs unusually clear for a riverbank spring: more than one account calls it crystal clear, and the photographer whose picture illustrates this listing, camped on the bench above, called it “a really nice, deep pool” and his favorite kind of first night.

Depth and heat both follow the river. At moderate flows the pool is a proper soak with the cold river a step away for a plunge; as flows fall further the pool warms and shallows; and at high water it simply ceases to exist, which is why the outfitters who run this river describe Trail Flat as a sometimes stop, worth it when the flows and the timing line up.

Most soaks here happen in the evening of the first day out of Boundary Creek, with the whole river still ahead.

Fees, Hours & Reservations

The spring itself is free: no fee, no ticket, no reservations for a soak. Reaching it is what is regulated. A Forest Service float permit is required to float the Middle Fork at any time of year, and launches during the control season, May 28 to Sep 3, are allocated through the Four Rivers Lottery on Recreation.gov. Floating costs a $4 per person per day recreation fee, plus a $6 application fee for a lottery or reservation.

Licensed outfitters run permitted trips all season for anyone who does not draw or does not boat. Hikers on the Middle Fork Trail need no float permit, but the river camps are managed for permitted river parties during the season, so plan overnight stops accordingly.

Facilities, Lodging & Nearby

There are no facilities of any kind: no toilet building, no drinking water, no trash service, and no cell coverage. Trail Flat camp is a bench and a bar used by assigned float parties, who carry in everything, including the portable toilet and fire pan the permit requires, and carry everything back out. The nearest services of any kind are in Stanley, on the far side of a float or a hike.

The neighboring camps are Big Bend at mile 6.5 on the right bank and the Boy Scout camp upriver, and the first rapids of consequence, the Chutes, wait at mile 8 the next morning.

History

Trail Flat belongs to the oldest layer of this river’s story. The Forest Service’s river guide records that bone chips, tools, and mussel shells in the rock shelters along these canyon walls confirm people were living along the Middle Fork more than 8,000 years ago, and a warm pool at the edge of a fish-rich river would have been known to every one of those generations.

In the modern record the flat appears as one of the established camps in the Forest Service’s river guide, its hot springs noted in a single practical sentence that has not needed updating since: washed out at high water, usable at lower water. Generations of float trips have made it their first camp and their first soak, which is a quieter kind of fame than the big springs downriver get, and the regulars seem to prefer it that way.

Safety & Health

Never count on this spring being there. At high water the river covers it completely, and the Middle Fork at runoff is cold, fast, and unforgiving; if the pool is not visible on the bar, it is not a soak that day. When the pool is in, test the water before you get in: a riverbank pool can run hotter than it looks near the spring vent, and its temperature shifts with the river. The bar is loose rock and the bottom is silty, so move carefully.

Red spider mites have been reported at this hot spring, so keep clothing and towels off the rocks and ground around the pools; our red spider mite guide covers what they are and how to avoid taking them home.

Beyond the pool, this is deep wilderness: help is a long way in either direction and every party travels self-supported. Soak sober, and leave the pool ring tidy for the next camp.

Best Time to Visit

Mid summer through fall, as the river drops. June trips often find the spring still buried or just emerging, and spring runoff is out entirely. By July in most years the pool is formed, and late summer and early fall bring the best combination: a clear, hot pool, cold river beside it, and camps that shake out the first-night crowds.

If you arrive on an early trip and find only river where the pool should be, the next reliable soak is Sheepeater, about 6 miles downriver, whose terrace pools sit above the high water line.

Nearby Hot Springs

The Middle Fork strings six named hot springs along its first 52 miles. Sheepeater Hot Springs, about 6 miles downriver at mile 13, is the next soak: several pools on a terrace above the river that stay usable when this one is washed out.

Far downriver, the run ends at Hospital Bar Hot Springs at mile 52.1, the last hot springs camp on the river. More East-Central Idaho hot springs →

Frequently Asked Questions

Where is Trail Flat Hot Springs?

At the edge of the Middle Fork of the Salmon River at Trail Flat camp, river mile 6.9 from the Boundary Creek launch (outfitter guides mark the spring at mile 7.3), in the Frank Church River of No Return Wilderness in Valley County. The pool sits on the gravel bar just below the camp bench.

How do you get to Trail Flat Hot Springs?

By river or by trail. Nearly everyone arrives on a permitted Middle Fork float trip launched at Boundary Creek, usually as the first night’s camp. The Middle Fork Trail from Boundary Creek also reaches the camp at about 7 miles. There is no road access.

When can you soak at Trail Flat Hot Springs?

From mid summer into fall, when the river has dropped. The Forest Service guide is blunt about the spring: it is washed out at high water and usable at lower water. During spring runoff the pool is under the river and does not exist as a soak.

How hot is Trail Flat Hot Springs?

No agency or survey figure for this spring was found in the sources consulted. The pool is spring water rimmed by the cold river, so its heat follows the river level: warmest and clearest at moderate to low flows. Test it before you get in.

Do I need a permit for Trail Flat Hot Springs?

The spring has no permit of its own, but floating the Middle Fork requires a Forest Service permit year-round, with control season launches (May 28 to Sep 3) allocated by the Four Rivers Lottery on Recreation.gov. Floating costs $4 per person per day plus a $6 application fee.