Up to 50,000 people in Louisiana's Tangipahoa Parish were ordered to evacuate Thursday morning when water from Tropical Storm Isaac threatened to overwhelm a dam across the state line in Mississippi.
The dam at Percy Quin State Park in Mississippi is located at the southern end, seen here with a blue bullet.
Residents were given just 90 minutes to leave, parish spokesman Jeff McKneely told NBC affiliate WDSU-TV.
The parish said "imminent failure" of the dam was expected.
Mississippi officials, however, said they didn't think the volume of water in the 700-acre lake at Percy Quin State Park near McComb, Miss., would add enough flow to threaten communities downstream.
Am I the only person who has no pity for people who don't get the hell out of dodge when a hurricane is announced. It's not like an earthquake where it just happens we get to watch these things gradually come to the US. If you're still there when it gets there it's your own fault.