While visiting Grand Teton National Park, we chose to stay in the small town of Alpine, Wyoming about an hour south of Jackson. Have you been to Jackson? What a mess. Bumper to bumper traffic, nowhere to park, people everywhere. And, outrageously expensive. So, we took ourselves to Alpine where we found a lovely AirBnB with a fantastic porch with wonderful views of the Star Valley. Thankfully, we did, as otherwise we would have never heard of the Periodic Spring.

What is the Periodic Spring you ask? Well, let me tell you. The Periodic Spring, also called the Intermittent Spring, is located in Swift Creek Canyon, near the town of Afton (where you will find the world’s largest arch made of elk antlers — 3000 antlers in fact). From approximately September until May, the spring runs up to 100 cubic feet per second of water. It is loud. Well, for a bit.

Then, it stops for 10-20 minutes (or 12-18 minutes or other time intervals, depending on who you believe).

And gets quiet. Then, it starts again.

From what I’ve read, nobody is really sure why this happens. The going theory is that there is an underground lake with a passage out to the spring that acts like a siphon. When there is lots of water (e.g., in the spring and summer), the spring runs continuously. But, when there is less water, the spring stops running when the lake gets low and while the lake refills. Once the level of the underground lake gets high enough, a siphon like structure pulls water out of the lake until the lake level drops too low for the siphon to work, and the whole process starts again.

Apparently, there are only a handful of springs like this in the entire world, and Periodic Spring is thought to be the largest. That alone would make it worth a stop, but the short hike there and back (only 1.5 miles round trip) was beautiful.

If you are ever in the area, a visit is highly recommended.