A form of undeveloped hot springs spa that is not common in other states but is common in Oregon, and it is paid for.
It was in a national forest and reasonably well managed.
On top of a hill of tufa
A four-hour drive from Portland and eight hours from the Bay Area, Umpqua Hot Springs is hard to reach for most travelers.

I found many similarities with the Terwilliger Hot Springs in the same state.
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Reference:Terwilliger (Cougar) Hot Springs - Hot Springs in Oregon
Hot mineral water with faint sulfur smell flows down along the series of rock walled pools. Terwilliger is one of the most popular clothing optional natural hot springs in the State of Oregon. Near hippie town One of Eugene's many ...
Both are located in national forests, require a fee, require light hiking, and are popular spots.

There was a parking lot at the end of a dirt road in good condition.
This was a day use only area and camping was not allowed.

The fee was only $5.00 per car/day (as of this writing).
There was no attendant present at the time of my visit, so I put the money into the box.

After crossing the rainbow-colored bridge, I climbed 0.8 miles round trip.
Although the distance was short, it was steep.

Once you find a graffiti-colored vault toilet, the hot springs are just around the corner.

Reddish-brown tufa was deposited in the form of hills, and a stream flowed far below.

The hot springs consisted of roughly six pools, all of which were primitive and were made by volunteers who hollowed out the precipitation.
The rule is clothing optional, and some people were seen naked.

Covered by a crumbling roof was the main pool.
It was large enough to accommodate five soakers.

There was no gush at this location, and all the hot water was drawn from the source above it.

The water temp in the main pool was 106 degrees F.

The hose could be manipulated to prevent it from getting too hot.


Mitchell Friedman – Umpqua Hot Springs, Oregon (2011) CC BY 2.0
The overflowing water flowed down the slope over a wide area.

In places, I found hollowed-out hot pools.

The tufa mound was a natural cooling system as well as a natural art form.
The lower one went, the more lukewarm the water became.

A pool surrounded by rocks could be seen down to the riverbank.
The naturally flowing thermal water was being used to its fullest by taking advantage of the difference in elevation.

Hot water straight out of the ground
Now that we have enjoyed the unparalleled full view of the Umpqua Hot Springs, it is time to take a long soak in the water.
The hot water from the source, which is the highest, flowed into all the other pools.

At first glance, it looked like muddy water, but don't worry.
The bottom surface was soft soil, but the muddy water was of hot spring origin and clean enough.

Gushing straight out of the ground with occasional bubbles.
A little hot, 111 degrees F.

When I sink my body into the pool after enduring the heat, I strongly felt the metallic smell.

I have the impression that the paid wild hot springs found in Oregon are usually nice.
They are reasonably well manned, reasonably well left alone, and wonderful.

Summary
Umpqua Hot Springs, Umpqua National Forest, Oregon, U.S.
My rating
Type: Undeveloped (fee required)
Rule: Clothing optional
Chemical use: No
Water temp: Up to 111 degrees F