A colorized satellite image shows Tropical Storm Isaac over the gulf states.… (NOAA )
Thousands of residents north and south of the Mississippi-Louisiana border were ordered to evacuate Thursday because of the possible failure of an Isaac-battered dam.
Officials are considering breaching the Lake Tangipahoa dam in order to direct water into a forested area and prevent massive flooding to low-lying residential communities downstream.
"If you live in these areas, leave immediately for higher ground,’’ the National Weather Service warned Thursday.
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Gordon Burgess, president of Tangipahoa Parish in Louisiana, called for the mandatory evacuation -- believed to be about 40,000 to 60,000 residents -- along the Tangipahoa River.
The Mississippi Emergency Operations Center called the evacuation "precautionary.’’
"The dam at the 700-acre lake has NOT been breached,’’ the emergency operations center said in a statement. Engineers were assessing the damage.
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Louisiana Gov. Bobby Jindal called the situation “very, very fluid.”
Although the dam is in southern Mississippi, Louisiana officials say communities in their state would be hard-hit if the dam fails. “Once it breaks, it will take 90 minutes to reach the city of Kentwood in Louisiana,” said a Louisiana state spokeswoman.
Jindal said officials were thinking about breaching the dam, but nothing has been decided. Mississippi officials would likely make the decision, according to Louisiana officials.
Jindal said state officials would be taking the parish president up in a helicopter to survey the river after the briefing so that “he can see the dam himself.” Jindal and Burgess planned to hold a news conference this afternoon to provide an update.
The governor said the slow-moving storm threatens other areas of the state as well.
“Even though the water is beginning to recede, we will see high tides in those areas throughout the weekend,” he said.
“Evacuation efforts continue this morning," he added, saying emergency responders were assisting approximately 30 evacuees an hour. With the Tangipahoa evacuation, he added, “those numbers are about to increase dramatically.”
Already, more than 6,000 people were in shelters across Louisiana Thursday, he said.
In Plaquemines Parish to the south of New Orleans, where more than 130 people were evacuated due to flooding over the east bank levee Wednesday, Jindal said officials planned to breach a levee between 2 to 3 p.m. Thursday to allow floodwaters to recede.
Also, more than 3,200 people were evacuated overnight from St. John the Baptist parish due to rising flood waters, Jindal said.