Periodic Spring-"The Spring That Breaths"
North edge of Afton on U.S. Highway 89

What Is It? The Periodic Spring is North America’s only cold water geyser and is the largest of the three known fluctuation springs in the world. Its name is descriptive of the periodic flow, which during the fall and winter, turns on and shuts off every 12-20 minutes. These periodic flows are less noticeable during high water months in spring and summer.

The water at Periodic Spring has given life to the land, the wildlife, and the people of Star Valley. Historically, Native Americans traveled great distances to cure their ills by bathing in “the spring that breathes.” Since 1958, the spring’s water has been piped to the City of Afton for its municipal water supply, and is used for drinking, irrigation, and generating electricity.

No one knows for certain what makes the Periodic Spring start and stop. One theory is that underground streams carry melting snow and rain water to a lake deep in the Salt River Mountains. When the lake level gets high enough, a natural siphon draws the water from the lake to the surface like a faucet being turned on and off. The water then gushes out of a sheer ledge and cascades down a wild, moss-covered ravine to join Swift Creek. The flow continues until the water level in the lake drops below the siphon’s intake level, allowing air to enter the siphon from the lake cavern. The flow stops until the lake rises again and the cycle repeats.