They are saying that this will affect 50,000 to 60,000 people.

This was at 10:30 AM 08/30/12
Published: Thursday, August 30, 2012, 10:31 AM Updated: Thursday, August 30, 2012, 10:31 AM

By Jeff Adelson, The Times-Picayune



Isaac, dam failure prompts mandatory evacuation near Tangipahoa River

BATON ROUGE -- Tangipahoa Parish officials have issued a mandatory evacuation for communities near the Tangipahoa River because Percy Quin Dam in Mississippi is expected to fail, officials said Thursday. The dam in Pike County is in imminent danger of failure due to flooding from Hurricane Isaac, officials said.
U.S. Rep. Steve Scalise announced that parish President Gordon Burgess called for immediate, mandatory evacuation on his Facebook page, saying the dam on Lake Tangipahoa is in "extreme danger" of failing.
The evacuation area runs from Kentwood to Robert along the river, he said.

Isaac, dam failure prompts mandatory evacuation near Tangipahoa River | NOLA.com