|Location||Iberia Parish, Louisiana|
|Primary inflows||estimated 8.47 cubic feet (0.240 m3) per second from catchment|
|Primary outflows||unknown to Delcambre Canal|
|Catchment area||10.2 square miles (26 km2) of the Vermilion-Teche Basin|
|Basin countries||United States|
|Surface area||1,125 acres (5 km2)|
|Average depth||3 feet (1 m)|
|Max. depth||200 feet (61 m)|
On November 20, 1980, a Texaco oil rig accidentally drilled into the Diamond Crystal Salt Company salt mine under the lake. Because of an incorrect or misinterpreted coordinate reference system (the drillers thought the coordinates were in the Universal Transverse Mercator coordinate system when they were in transverse Mercator projection) the 14-inch (36 cm) drill bit entered the mine, starting a chain of events which turned the lake from freshwater to salt water, with a deep hole.
It is difficult to determine what occurred, as all evidence was destroyed or washed away in the ensuing maelstrom. One explanation is that a miscalculation by Texaco about their location resulted in the drill puncturing the roof of the third level of the 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 soil and salt were washed into the mine by the rushing water, filling the enormous caverns left by the removal of salt over the years. Another explanation is an underwater stream naturally eroded into the enormous salt plug, inevitably making a sinkhole below the lake, which could have been exacerbated by Diamond Crystal illegally and dangerously mining in certain areas.
The resultant whirlpool sucked in the drilling platform, eleven barges, many trees and 65 acres (260,000 m2) of the surrounding terrain. So much water drained into those caverns that the flow of the Delcambre Canal that usually empties the lake into Vermilion Bay was reversed, making the canal a temporary inlet. This backflow created, 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 Vermilion Bay. The water downflowing into the mine caverns displaced air which erupted as compressed air and then later as 400-foot (120 m) geysers up through the mineshafts.
There were no injuries and no human lives lost. All 55 employees in the mine at the time of the accident were able to escape thanks to well-planned and rehearsed evacuation drills, while the staff of the drilling rig fled the platform before it was sucked down into the new depths of the lake, and Leonce Viator, Jr. (a local fisherman) was able to drive his small boat to the shore and get out. Three dogs were reported killed, however. Days after the disaster, once the water pressure equalized, nine of the eleven sunken barges popped out of the whirlpool and refloated on the lake's surface.
The drilling company, Texaco and Wilson Brothers, paid $32 million to Diamond Crystal and $12.8 million to nearby Live Oak Gardens plant nursery in out-of-court settlements to compensate for the damage caused. The mine was finally closed in December 1986.
Since 1994, AGL Resources has been using Lake Peigneur's underlying salt dome as a storage and hub facility for pressurized natural gas. There was concern from local residents in 2009 over the safety of storing the gas under the lake and nearby drilling operations.
The lake had salt water after the event, not as a result of salt from the mine dissolving into the water, but from the inflow of salt water from the Delcambre Canal and Vermilion Bay, which are naturally salty or brackish. The event permanently affected the ecosystem of the lake by changing the lake from freshwater to saltwater and increasing the depth of part of the lake.
- Lake Peigneyr TMDLS for dissolved oxygen and nutrients EPA 2002 report
- Lake Peigneur - Oil rig disasters - Offshore Drilling Rig Accidents
- "Lake Peigneur Disaster". Archived from the original on 2007-12-30.
- Bellows, Alan. "Lake Peigneur: The Swirling Vortex of Doom". Damninteresting.com. Retrieved 2013-08-26.
- paulwal222. "Jefferson Island Salt Mine Collapse: The REAL story of Lake Peigneur". YouTube. paulwal222. Retrieved 30 June 2015.
- Jefferson Island Storage and Hub Q & A AGL resources, 2007, (map of lake showing current and planned gas caverns)
- AGL Resources Seeking Customer Interest in Project to Expand Jefferson Island Storage & Hub Facility Press Release, 2005-10-27
- "Lake Peigneur Update". WorldNow and KLFY. December 9, 2009. Retrieved November 20, 2013.