By Matt Williamson, APFirefighters pump water out of Lake Tangipahoa in an effort to relieve pressure on Percy Quin Dam, which faced the threat of flooding after being inundated with rains from Hurricane Isaac.
By Matt Williamson, APFirefighters pump water out of Lake Tangipahoa in an effort to relieve pressure on Percy Quin Dam, which faced the threat of flooding after being inundated with rains from Hurricane Isaac.
A few phone calls later, amid National Weather Service and media reports that the dam would fail, the Tangipahoa, La., parish president Gordon Burgess, just over the state line and downstream of the lake, called for nearly half of the rural parish to evacuate. Louisiana Gov. Bobby Jindal sent 200 buses to fetch evacuees and helicoptered with Burgess over Mississippi to survey the earthen dam himself.Now, 10 days later, the dam still holds and the crisis has ended. Evacuees — the few thousand that there were — have returned to their homes. Tangipahoa is $6 million in the hole for its disaster response and evacuation.And Burgess, parish president for 26 years, says he'd make the same decision all over again."I'd rather say we wasted our efforts than have someone lose a life," Burgess says. "What if we lost one person? It was worth it not to lose a life."The near-disaster has prompted Mississippi to push forward with long-delayed plans to rebuild the 1930s-era dam, but it also raises questions about when officials should order evacuations and whether anyone will listen."You're erring on the side of caution," says Barry Scanlon, president of Witt Associates, a disaster management consulting firm founded by former FEMA administrator James Lee Witt. "A few more hours of stalled Isaac and it may not have turned out so well."Evacuations are costly, disruptive and wearying. New Orleans, bolstered by a new levee system, told its residents to stay put, while south of the city the parish president of Plaquemines told most of the parish to get out ahead of the storm surge. In coastal Mississippi, Biloxi Mayor A.J. Holloway said after the storm inundated the city that he wishes he had ordered a mandatory evacuation."These are not decisions that a governor or mayor make lightly," Scanlon said. "They understand how much it will disrupt the community. They understand the cost."Burgess of Tangipahoa is still tallying the costs, but he estimates the parish of 120,000 spent about $6 million. About 1,300 people evacuated to local shelters at schools and churches. Some residents sought refuge with friends and relatives on higher ground."In 26 years, no, I've never ordered an evacuation to this magnitude from the Mississippi line to Lake Pontchartain — 54 miles. That'll make you sit up and take notice," Burgess says. "We didn't know exactly how many people would be affected, whether it would be 1,000 or 10,000. It's a tough call, a tough call."To the south, New Orleans wrestled with the fraught possibility of not calling for a mandatory evacuation during a hurricane for the first time since Hurricane Katrina broke the city's levees and flooded 80% of the city in 2005.An evacuation order in New Orleans now triggers a hurricane plan that directs residents to 24 pickup points across the city, sends buses to fetch them and transports them to shelters, Mayor Mitch Landrieu said in an interview. A similar evacuation before Hurricane Gustav in 2008 moved thousands of residents out of the city and more than a million out of southern Louisiana.New Orleans requires mandatory evacuation if a storm reaches Category 3 status, with 111 mph or greater winds, five days before it is expected to hit land. Hurricane Isaac clocked in as a weak Category 1 storm with winds churning at 80 mph. But the categories measure only wind and don't factor in rainfall and storm surge. So on Monday, Aug. 27, less than 24 hours before Isaac struck, Landrieu was still weighing a mandatory evacuation."It's a very difficult call to make," Landrieu said. "The unpredictability of this storm's path and (storm) surge made it that much more difficult."Ultimately, New Orleans battened down and weathered the storm, closely monitoring its newly refurbished $14.5 billion hurricane protection system of levees, barriers and floodgates. That system was incomplete when Gustav struck.Ordering an evacuation — or not — is an imprecise science, Landrieu said."Some of it is guess work. Some of it is good planning. Some of it is making the best call with the best science you can get," Landrieu said. "But sometimes storms don't present themselves that cleanly."Evacuating each time a storm threatens can be economically and psychologically crippling to a city, especially after taxpayers spent billions on protection system, said Richard Campanella, a Tulane University geographer who has studied the improvements."If we're going to build this infrastructure to such high degrees and put all this money into it, we need to have enough faith in it that it's going to hold," Campanella said."The right decision was made."On the Mississippi/Louisiana border that Thursday morning, nothing about the situation was clear.Geologist and dam safety engineer Mike Meadows, of Mississippi's Department of Environmental Quality (DEQ) told the park manager Thursday morning to call the local emergency manager and notify the National Weather Service. Then he drove the two hours from Jackson to Pike County with dam safety engineer Natalie Sigsby, to inspect the dam, said James MacLellan, director of dam safety for the Mississippi DEQ.Before Meadows and Sigsby arrived around 9 a.m., the National Weather Service in New Orleans warned of flash floods in southwestern Pike County, downstream of the Tangipahoa River after local emergency management and law enforcement officials reported that the Lake Tangipahoa Dam is "expected to fail."Meadows and Sigsby surveyed the 2,300-foot long, 25-foot high dam and concluded "all we can do is monitor the situation" until the rain stopped and the river crested, MacLellan said. Once the water stopped rising, the engineers could use pumps to lower the water level to relieve pressure and dig a channel to direct water around the dam."If the dam was going to breach, there was nothing that could have been humanly done to stop it," MacLellan said.But, he said, early signs indicated the dam would hold."A slide is a nervous situation. We don't like to see it because there's not much we can do," he said. "But there was still 50 feet of clay between the water and the slide. It's a serious concern, but there are scarier situations."Col. Jeff Eckstein, commander of the Vicksburg District of the U.S. Army Corps of Engineers and a civil engineer, arrived that afternoon with two engineers. The real danger, Eckstein said, would come if the water overtopped the dam and washed away more of the earthen dam."The water was rising. You could see the two slides. It did not look good, but you could tell it was not about to fail," Eckstein said.MacLellan called media reports an overreaction."CNN was saying the dam had failed and there was a huge wall of water heading to Louisiana," he said. "Next thing we knew, there was a helicopter from Louisiana flying overhead of the dam."In Tangipahoa, Burgess and other parish officials were dialed in to the state's daily emergency briefing when they saw media reports that the dam was about to fail. Not long after, the governor's office called and told Burgess to order a mandatory evacuation for people living a half-mile on either side of the river — an order that the parish estimated would affect 30,000 to 40,000 people.The governor promised to send 200 buses, 39, Humvees, 27 high-water vehicles, 19 boats, 14 ambulances and 300 National Guard troops."Good gracious. It took me about 10 minutes to get my bearings," Burgess said. "In 12 hours, my parish might be inundated with water."Tangipahoa Parish had experienced flooding before. In 1983, the raging river had taken out the two-lane bridge in Amite that connects one side of the parish to the other, said parish spokesman Jeff McKneely.Burgess and his staff began calling local mayors, media and community organizations to spread the word. Parish offices filled with media from around the nation."My phone was ringing off the wall. We've got 100 or 200 lines. Seems like they all lit up at the same time," he said. "People would say, 'My place didn't get any water in the 1983 flood so I'm not going to leave.' And we would plead with them to get out of harm's way."The updates on the parish website on Aug. 29 between 9 a.m. and 1 p.m. offer a glimpse of the quickly changing information that spread among the states, the emergency managers, local officials and the media.The first alert warns of "imminent failure" of the dam at Lake Tanipahoa. A second alert says Mississippi's emergency management agency had notified the state and parish government that the dam "is failing." The third alert notes that the dam "is damaged but has not failed."When Jindal arrived, he took Burgess in his helicopter to see the dam."Looking at the dam, it was close to breaching. It had about 100 feet of slough. I was thinking, gosh, that could happen any minute," Burgess said.At a press conference after the flight, Jindal said Mississippi officials had told him the dam was still sound, but he urged residents to evacuate anyway "because we don't know that for a fact."Meanwhile, MacLellan had asked the U.S. Army Corps of Engineers to draw up new inundation maps that would show how far the water would go if the dam broke, so Louisiana would have an accurate way to determine which communities should evacuate. A National Guard combat engineer unit was dispatched to clear a forest and dig down through 30 feet of hillside to create a 600-foot long channel that would divert water around the dam arrived Thursday afternoon.On Friday morning, dam engineers decided they needed to drop the lake at least eight feet below to lift pressure and make repairs on the dam, MacLellan said. Since then, huge pumps on loan from the Army Corps of Engineers pumped 140,000 gallons a minute, dropping the lake about a foot a day. A week later, MacLellan said, the dam was stable and ready for reconstruction.Even without the dam breach, Tangipahoa suffered from serious flooding and 1,500 homes were damaged, McKneely said. The parish did not overreact, he said."I don't think you'll ever hear anyone say this was 'just' a Category 1," McKneely said.For more information about reprints & permissions, visit our FAQ's. To report corrections and clarifications, contact Standards Editor Brent Jones. 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