On 20 November 1980, it was a beautiful morning in Louisiana a disaster developed in or rather under lake Peigneur.  The Diamond Crystal Salt Corporation operated the Jefferson Island salt mine next to and under the lake, at the same time at the Surface a Texaco oil rig was drilling down from the surface of the lake hunting for petroleum. Due to a miscalculation, the 14-inch (36 cm) drill bit entered the mine, starting up a chain of events which turned what was back then an almost 10-foot (3.0 m) deep fresh water lake into a salt water lake with a deep hole.

 

It's difficult to determine exactly what took place that day, as many of the evidence was destroyed and washed away in the resulting maelstrom (a very powerful whirlpool). One explanation is that a miscalculation by Texaco regarding their specific location resulted in the drill puncturing the roof of the third level of the Salt mine. This created an opening in the bottom of the lake. The lake then drained into the hole, expanding the size of that hole as the dirt and salt were washed into the mine by the rushing waters, filling up the massive caverns left by the removal of salt over the years since the opening of the mine in 1919 . The resulting whirlpool sucked in the Texaco drilling rig, eleven large barges and a great number of trees including 65 acres (260,000 m2) of the surrounding terrain. Because of the tremendous amounts of water that drained into the caverns the flow of the Delcambre Canal that usually empties the lake into the Gulf of Mexico was reversed, making the canal a temporary inlet. This backflow produced, for a few days, the tallest waterfall ever in the state of Louisiana, at 164 feet (50 m), as the lake refilled with salt water from the Delcambre Canal and the Gulf of Mexico . The water downflowing into the mine caverns displaced air which inturn erupted as compressed air and then later as 400-foot (120 m) geysers up through the mineshafts.

There were luckily no injuries and no human lives lost. All 55 people in the mine at the time of the accident were able to escape thanks to well-planned and rehearsed evacuation exercises, while the crew of the drilling rig fled the platform right before it was sucked down into the new depths of the lake. Three dogs were reported killed however. Several days after the disaster, once the water pressure equalized, 9 of the 11 sunken barges popped out of the whirlpool and refloated on the lake's surface.

 

The lake had salt water after the event, not as a direct result of water entering the salt mine, but from the salt water from the Delcambre Canal and the Gulf of Mexico , which are naturally salt or brackish water. The event permanently disturbed the ecosystem of the lake simply by changing the lake from freshwater to saltwater and increasing the depth of a big part of the lake. After the disaster the mine was closed in early December 1986.