The excessive rainfall drenching Mississippi from Tropical Storm Isaac has prompted a flash flood emergency and the evacuation of thousands ahead of a potential dam break.
The National Weather Service issued a flash flood emergency for southwestern Pike County for a potential dam failure along the Tangipahoa River, just east of McComb.
The river is forecast to rise rapidly to nearly one foot above its record flood stage of 18.7 feet by Friday afternoon. NWS says the river could hit 19.4 feet.
Officials believe this will likely cause the 700-acre Lake Tangipahoa earthen dam, also known as the Percy quin dam to break, causing widespread and significant flooding downstream of the river.
Pike County Emergency Management Director Richard Coghlan said they may make a cut on one side of the lake to relieve pressure and drain it over the next several days.
Residents of 19 houses and seven mobile homes, along with three businesses, below the lake were asked to evacuate in the local area.
The Mississippi Emergency Management Agency does not expect a catastrophic event, said spokesman Greg Flynn.
McComb Mayor Whitney Rawlings said there was a 50 percent chance the dam would fail. He said it was currently holding, but the concern is that it would eventually give.
“What they’re doing now is saying, ‘OK, this thing might go. People need to be moving now in case it does go.’ And lord only knows if this thing holds or not,” Rawlings said.
Downstream in Louisiana, Tangipahoa Parish President Gordon Burgess called for a mandatory evacuation within a half mile of the Tangipahoa River.
A mandatory evacuation was called for residents living within a half-mile along the Tangipahoa River in Kentwood, an area that would affect up to 2,200 people.
Louisiana Gov. Bobby Jindal said the move was a precaution because if the dam were to break, it would only take 90 minutes for flood waters to swept through the town.
Jindal had ordered buses to be sent to the area to immediately help evacuate residents.