Water levels at Yellowstone Lake in Wyoming dropped 11 feet between Sept. 26 and 27, 2026.
In late September 2026, social media posts began sharing a fictional story claiming that Wyoming’s Yellowstone Lake had experienced a dramatic overnight drop of nearly 11 feet.
A widely shared Facebook post from late September stated:
YELLOWSTONE NATIONAL PARK – Scientists are investigating after portions of Yellowstone Lake reportedly dropped nearly 11 feet overnight when an unknown underground channel opened beneath the lake bed.
Rangers first noticed the change Sunday morning after several docks were found sitting completely above the waterline. Geologists believe shifting rock beneath the lake may have opened a previously sealed underground passage, allowing millions of gallons of water to drain into Yellowstone’s extensive subterranean geological system.
The narrative quickly spread across other platforms, including X and Threads.
The story originated from a Facebook page named Casper Planet. The page explicitly identifies its material as fictional, stating in its “About” section that it publishes satirical content and uses entirely fabricated names and locations.
Aside from the publisher’s own disclaimers, no mainstream news outlets or official monitoring agencies reported any such event at Yellowstone Lake. Furthermore, the fictional story featured a fabricated quote attributed to a nonexistent geologist named Dr. Aaron Keller.
The accompanying image used in the viral posts was also found to be entirely artificial. Analysis by AI detection tools, including Pangram and OpenAI’s Verify scanner, confirmed that the visual was generated using artificial intelligence.
While Casper Planet acknowledges its satirical nature on its primary profile, the specific posts shared across platforms like X and Threads lacked any context indicating they were fictional.
Official water monitoring data from the United States Geological Survey (USGS) for the Yellowstone River inlet at Yellowstone Lake contradicted the online rumors entirely. Measurements taken between Sept. 26 and Sept. 27 showed standard fluctuations of only a few inches, with no sign of a sudden drop.
The same satirical page has previously generated other fictional regional rumors, such as claims regarding an ancient city hidden beneath Wyoming’s Horse Peak Mountain or fictional wildlife encounters involving wolves.