Snowmelt and a healthy dose of rain last weekend flooded the Middle Fork of the Popo Agie River with more water than the limestone cavern it flows into could contain.
The famed Sinks of the Popo Agie is a cavern entrance where the Middle Fork goes underground, flowing into a series of cracks and fissures in the limestone. The water reappears just down the canyon in a pool called the Rise — tranquil on its surface compared to the boiling mountain stream up canyon. But a closer look shows a constant upwelling of water as the Middle Fork of the Popo Agie bubbles back up from beneath.
When streamflow is low, visitors can see well into the cave at the Sinks. But on Wednesday, only a small gap still appeared between the top of the boiling stream and the roof of the cavern. With the Sink full, water flowed into an overflow channel that only becomes active when the flows are too high for the Sink to contain.