On the morning of 20 November 1980, what began as a calm day in southern Louisiana escalated into one of the most extraordinary industrial accidents in U.S. history—beneath Lake Peigneur.

At the time, Diamond Crystal Salt Company operated the Jefferson Island salt mine, which extended underneath the lake. Simultaneously, Texaco was drilling for oil from a platform positioned on the lake’s surface. Due to a critical miscalculation of drilling coordinates, Texaco’s 14-inch (36 cm) drill bit penetrated the roof of the mine’s third level, initiating a catastrophic chain of events.

The breach created an opening in the lakebed, allowing water to rush into the mine. As freshwater poured into the underground caverns, it rapidly eroded salt and sediment, enlarging the hole and collapsing additional mine passages. What had been a nearly 10-foot (3 m) deep freshwater lake transformed into a violent maelstrom.

The resulting whirlpool swallowed the drilling rig, 11 large barges, and vast amounts of surrounding land—approximately 65 acres (260,000 m²)—along with countless trees. The immense outflow of water caused the Delcambre Canal, which normally drains the lake into the Gulf of Mexico, to reverse direction. For several days, the canal became a temporary inlet, refilling Lake Peigneur with saltwater from the Gulf.

This reversal produced what was briefly the tallest waterfall ever recorded in Louisiana, plunging 164 feet (50 m) into the mine caverns. As water displaced trapped air underground, compressed air erupted through mineshafts, creating geysers reaching up to 400 feet (120 m) high.

Despite the scale of the disaster, no human lives were lost. All 55 miners underground escaped safely due to well-planned evacuation procedures, and the drilling crew abandoned the rig moments before it was consumed. Tragically, three dogs were reported killed. In the days following the event, once pressures equalized, nine of the eleven sunken barges resurfaced and refloated on the lake.

The lake’s salinity changed permanently—not directly because water entered the salt mine, but because salt and brackish water from the Delcambre Canal and the Gulf of Mexico flowed inward during the reversal. The ecosystem was irreversibly altered as the lake shifted from freshwater to saltwater and gained significant depth in large areas.

The Jefferson Island salt mine was ultimately closed in December 1986, marking the end of operations beneath Lake Peigneur and cementing the incident as a lasting lesson in geological risk and industrial oversight.