Yellowstone National Park‘s geology team has a problem that never quite seems to go away. Visitors keep throwing rocks, sticks, coins, and just about everything else into the park’s hydrothermal features, and cleaning them out is an exhausting, never-ending job.
The objects thrown into these features can have real consequences. Minute Geyser in Norris Geyser Basin once shot water 60 feet into the air before a single thrown rock plugged its vent in 1947. It hasn’t erupted since.
Morning Glory Pool, one of the park’s most photographed features, has cooled and changed color after decades of visitors tossing in coins and debris. More than 6,574 coins have been pulled from the pool so far. Handkerchief Pool stopped functioning entirely in 1927 after visitors spent years dropping linen into its vent, and it took two decades to recover.
The clean up efforts to revive these features are truly enormous. A small hot spring near the Grand Prismatic Overlook was fully remediated in 2020, then completely filled back up with debris by 2025. That summer, the geology team pulled more than 6,000 objects from the feature alone.
At Solitary Geyser in 2021, crews removed 15 logs, some weighing up to 90 pounds, along with basketball-sized rocks and hundreds of smaller pieces cemented in place by silica sinter. Other springs that same year gave up 16 entire trees, 5 stumps, and a bizarre assortment of objects including religious figurines, a crystal ball, a football, and an unopened beer.
The tools required for the cleanup range from shovels and strainers to 16-foot extendable hooks. After each remediation, water flow and temperatures typically rise again, confirming the damage the debris had caused.
With over 4 million visitors annually and more than 10,000 hydrothermal features to protect, Yellowstone staff have just one simple ask. Leave rocks and sticks where they are, and throw nothing into the springs.
