Lake Peigneur is the deepest lake in Louisiana. The Shreveport Times puts it at about 200 feet at its deepest point, which is a pretty odd number in a state where most lakes are about as deep as a backyard pool. And it didn’t get that way slowly. It got that way on a Thursday morning.
Before November 20, 1980, the lake covered about 1,000 acres and ran 4 to 15 feet deep, according to the federal Mine Safety and Health Administration (MSHA). Then an oil rig working on top of it ran into trouble, the salt mine underneath flooded, and by late morning the lake was basically gone. I spent a good chunk of today reading MSHA’s investigation of the disaster, and the agency still can’t tell you who caused it.
So what was under the lake?
Jefferson Island, on the lake’s southeast shore, sits on top of a salt dome. If that term is new to you, it’s basically a giant plug of rock salt that pushed its way up from deep underground over a very long time. The one under Peigneur measured roughly 6,300 feet across, and most of it lay under the water.
Salt had been mined there since the early 1920s, and by the time of the accident Diamond Crystal Salt Company’s mine employed 297 people and had workings on levels 800, 1,000, 1,300 and 1,500 feet down. The rooms on the deepest level were 160 feet wide and 75 feet tall, with pillars of salt 240 feet square holding the roof up. You could pretty much stand a seven-story building in one of them, and you’ll want to keep that in mind once you start wondering where a lake could go.
Texaco, meanwhile, was drilling for oil right next door. Its well P-20 was out on the water about 2,150 feet southwest of the mine’s main shaft, drilled from a platform by a contractor called Wilson Brothers.
The rig went first
Wilson Brothers drove a 16-inch steel conductor pipe 91 feet into the lakebed on November 17, and the crew started drilling the next evening with a 14¾-inch bit. For a day and a half it was mostly routine, apart from a couple of balky mud pumps. Then, at about 4:40 a.m. on November 20, the driller found the drill pipe stuck somewhere between 1,228 and 1,248 feet down. The pipe wouldn’t budge in any direction.
The crew had also lost circulation. In plain English, the drilling mud they were pumping down the hole to cool the bit and carry the cuttings back up had stopped coming back. Mud that goes down and doesn’t come up is going somewhere, and one of the classic reasons is a hole that’s run into an open space or a very porous layer.
The gauges got weirder from there. The drill string weighed 78,000 pounds, but the weight indicator kept climbing, first to between 200,000 and 240,000 pounds and eventually past 400,000. Around 5:45, as the next shift showed up, the driller heard popping noises from somewhere under the rig. Then the platform started to lean.
The crew figured some of the pilings under the platform had given way, which apparently isn’t all that unusual, and somebody called a contractor to come out and level it. That plan didn’t last long. Once one corner had dropped 2 or 3 feet, the foreman ordered everyone off. He, the toolpusher and the driller cut the supply barges loose, and a tugboat called Charlie towed them clear. At 7:25 a.m., two Texaco assistant district superintendents watched the whole rig roll over and disappear into water they knew was less than 11 feet deep.
We’ve covered a tunnel borer that came up through the bottom of an Oklahoma lake on purpose and another that chewed 2.7 miles under Lake Mead. This is the version nobody planned.
Meanwhile, 1,300 feet down, nobody knew a thing.
Just before 7 a.m., 48 miners and three visitors from LSU had gone down into the mine. At around 8:10, master electrician Junius Gaddison was gathering equipment on the 1,300-foot level when he heard banging. He looked up the tunnel and saw a muddy stream more than 2 feet deep heading his way, knocking fuel drums into each other as it came.
Gaddison didn’t waste a second. He shouted a warning, grabbed the switch that fed power to the lower level and flicked it off and on three times, which was the mine’s evacuation signal. A maintenance foreman drove a truck out to the far corners of the 1,500-foot level to pick up four men who were working out of sight of the lights. With water already pouring into the 1,300-foot station, the cage was sent to the 1,000-foot level instead, and between 8:40 and 9 a.m. everyone was hoisted out in four trips. Nobody was hurt.
That’s frankly a textbook evacuation, and MSHA’s report credits every person underground and on the surface with following the procedures to the letter.
Then the lake left
The flooding sped up fast. Salt dissolves in water, so every gallon that went down the hole made it a little bigger, and there’s no shutting a valve on that. A whirlpool around a quarter of a mile across opened up on the lake, and MSHA says it caught a tugboat, a string of barges and two Texaco oil rigs. Texaco’s other well near the mine, No. 35, was being drilled on land about 400 feet back from the shore, but the report doesn’t spell out exactly which two rigs went into the crater.
Two fishermen, Leonce Viator and his nephew Timmy Dore, were out on the water when it started. Viator told UPI, “I thought it was the world coming to an end.” The two of them made it to the bank, tied up to a tree and ran, and Viator said they looked back in time to see the tree get pulled into the swirl.
MSHA’s timeline says the whole lake was gone within three hours. The air trapped in the mine had to go somewhere, too, and it blasted out of both shafts hard enough to twist the cage in the air shaft and damage the enclosure over the main one. Around 1 p.m., the air shaft threw a shower of mud and water across the site.
On the surface, about 65 acres along the southeast shore, including part of the island’s Live Oak Gardens, slumped below the lake’s normal level. Greenhouses were demolished. A Texaco gas well on the shore had its casing damaged by the ground movement, and the escaping gas caught fire and burned on the water roughly 200 feet out.
Where did the water to refill it come from?
Normally, water flows out of Lake Peigneur through the Delcambre Canal toward Vermilion Bay and the Gulf of Mexico. With the lake empty, the canal ran backward for two days, pouring water from the bay side into the crater until the lake was full again. About 30 shrimp boats tied up along the canal ended up sitting on the mud as the level dropped, and they had to be floated off later.
That backward flow made a waterfall where the canal met the crater, and you’ll find plenty of articles telling you it was 164 feet tall, the tallest in Louisiana’s history. I can’t find that number anywhere in the federal report. The only measurement MSHA gives comes from an aerial survey the next morning, when the water in the crater sat 40 to 50 feet below the normal lake level and the canal was still pouring in. Funnily enough, 164 feet is almost exactly 50 meters, so I’d guess somebody converted that 50 the wrong way at some point. The waterfall was real. I just wouldn’t bet on the 164.
The barge count has a similar problem. A local radio news director who flew over that evening told UPI she could see 10 barges, at least one rig and a tugboat at the bottom of the hole. Most later retellings say 11 barges went down and nine popped back up once the water evened out. MSHA only calls it a string of barges, so take the exact figures with a grain of salt. Which, given the setting, seems fair.
So who actually caused it?
I expected the federal report to settle that. It doesn’t.
Theories showed up within hours. A patrol commander at the Iberia Parish sheriff’s office told UPI the drilling wasn’t responsible, then admitted in the same breath that nobody was sure yet. Texaco said its bit had reached 1,228 feet and seemed to have broken through the ceiling of a cavern, but a company spokeswoman also said Texaco had never been told the mine shaft was there. Diamond Crystal said the drill hole plotted just inside a mined-out section on its map of the 1,300-foot level.
MSHA’s investigators couldn’t go down and look, because the mine was flooded and there wasn’t a way in. In August 1981, the agency laid out three possible causes. The first was the mine itself: engineering studies going back a decade had warned that the salt dome above the 1,300-foot level wasn’t stable, and a study from 1980 flagged a zone of excessive creep, which is salt slowly deforming under load, in the same general area where the water came in. The second was the drilling, since the stuck pipe sat at roughly the depth of the 1,300-foot level and the timing was hard to ignore. The report even noted the bit wouldn’t have had to break through, because getting close enough might have been enough to trigger a collapse. The third possibility was both at once.
Its conclusion fits in one sentence. MSHA said it was “not possible to determine the exact cause of the inundation.”
If you’re asking me, the third option sounds the most like how these things usually go: a structure that’s been getting weaker for years, and something that gives it a push. That’s my read, though. MSHA never made a finding either way, and nobody ever got to look inside to check.
The lawyers settled it instead. The Louisiana Endowment for the Humanities’ 64 Parishes encyclopedia cites a Baton Rouge Morning Advocate story from July 1983 headlined “Salt Firm Settles for $32 Million,” and notes that the hundreds of mine workers who lost their jobs were left out of the deal. The Jefferson Island mine never reopened as a salt mine.
The salt dome still has a job
You’d think a salt dome that swallowed a lake would get left alone after that. It didn’t. Since 1994, the dome under Peigneur has held natural gas in two caverns the operator has described as sitting about 4,000 feet below the lake’s surface. They’re made on purpose, by pumping fresh water down a well to dissolve a pocket in the salt and then pulling the brine back out. Salt’s pretty much gas-tight, which is why the Gulf Coast leans on it so heavily for storage.
The site, Jefferson Island Storage & Hub, has changed hands a few times. It now belongs to ONEOK, which finished buying EnLink Midstream in January 2025. Before that deal closed, EnLink approved an expansion to grow the site’s working gas capacity from 2 billion cubic feet to 10 billion cubic feet. Working gas is the gas you can actually pull back out and sell. The rest stays down there as a pressure cushion.
Residents around the lake have fought earlier expansion plans in court and at the state Legislature, and if I lived on that shoreline, I’d probably want to read every page of the permit file too.
EnLink’s third-quarter report to the SEC, filed after ONEOK had already bought control of the company, said the company expected to finish the Jefferson Island expansion in 2028, which would leave the dome that drank a lake holding five times its current working gas.
