The road for the last 200 yards is badly potholed. I hope my parking fee helps pay for some roadmending.
A Ranger Booth at the start of the trail leading to the pools is manned in the Summer, but empty in January. There is a $5 fee which goes towards maintaining the pools and parking lot (and the potholed road, please). When the Ranger isn't there you are supposed to put the money in an envelope and down a chute, but there were no envelopes either, so I wrote a description of my car and the date on a $5 bill and put that down the chute.
I had forewarning of potential nudity at the springs, having checked out the website. I packed swim trunks with my towel anyway. There were a couple of other vehicles in the car park, so I didn't expect to have the pool to myself.
The air is so clean at 2000 ft in the mountains that the trees are draped with moss and lichen. The path to the spring is much like any other trail through the woods, and maybe 1/4 mile long. As I approached the spring I could see water vapor rising through the trees, and a small changing hut. I could also see a young couple in their mid-20s bathing naked in the pool. Respecting their privacy I took one quick photo of the pools and then put my camera in my backpack.
There are a series of pools at Terwilliger, each lower one cooler than the one above, as water spills down the rocks. I stripped to my birthday suit and went initially to a lower pool, but it was no more than tepid so I soon came back up and joined the couple in the top pool.
This was my first experience of shared public nudity, so I wasn't sure what to expect. I said good morning but left it at that, and that was all the conversation as it turned out. The pool was slightly cooler than a bath might initially be run, but with hot water pouring in continuously from the spring at the top end, which came out of a small cave mouth. It was very relaxing, lying looking up at the vapor rising through the trees, absolute silence apart from running water and occasional birdsong. I hadn't brought any refreshments or entertainment, but the young couple had bottles of water which they occasionally sipped.
One problem with a natural spring is that there are bits of leaf, moss, and wood floating around in the pool, so every movement stirs up a cloud of debris which then settles on your body. This is at first fun, but makes it desireable to swish off the detritus before exiting the pool.
After maybe 3/4 of an hour I was wrinkling, and starting to feel light-headed as if I had spent too long in a sauna, so I called it a a day, got out and dried off quickly as it was chilly out of the water. While I was dressing a middle-aged man came along and joined the couple in the pool. I dressed rapidly before I cooled off, and still slightly damp, headed back to my car.
I stopped off at a couple of interesting places on the route back, including the nearby Cougar Dam.
This concrete tower, which reminded me of nothing more than a WW2 German bunker, is actually a temperature control station built in 2005, ensuring that warm water from the top of the reservoir is vented downstream. The reason for this is explained below.
Looking over Cougar Dam towards a small hydroelectric power station, a relatively green way Oregon can generate electricity.
At a small viewpoint next to the temperature station I learnt about the measures taken to ensure that water released downstream is at the correct temperature to encourage salmon. As you can see from the logo, the dam was built and is maintained by the US Army Corps of Engineers.
The reservoir level above the dam was much lower than I expected, and the highwater mark is shown by the twigs and branches that escaped the catch net.