The Coast Guard was searching the Gulf of Mexico near the Florida-Alabama state line Tuesday for a man who didn't return home from a water-scooter trip as Isaac was approaching. The search began after the man's wife called the Pensacola, Fla., station about 8:45 p.m. Monday, Chief Petty Officer Bobby Nash said.
North of New Orleans, St. Tammany Parish sheriff's deputies arrested three men accused of looting thousands of dollars of property from boats that had been docked near Slidell to protect them from the storm.
Otherwise, the damage so far in the United States was political: Republicans cut one day off their presidential nominating convention in Tampa, though in the end it bypassed the bayside city. Isaac is also testing elected officials along the Gulf from governors on down to show they're prepared for an emergency response.
Obama said Gulf Coast residents should listen to local authorities and follow their directions as Isaac approached.
"Now is not the time to tempt fate. Now is not the time to dismiss official warnings. You need to take this seriously," Obama said.
In Houma, a city southwest of New Orleans, people filled a municipal auditorium-turned-shelter. However, in the bayou country of Terrebonne Parish off Highway 24, storms pose a perennial dilemma for those living a hardscrabble life.
While some of the homes along Bayou Terrebonne and other nearby waterways show signs of affluence, this section of Louisiana 24 is mostly lined with trailer homes or small, often run-down houses. Staying could be dangerous, but many here who could be in harm's way have nowhere to go and little money to get there, especially given the high price of gasoline.
Monica Boudreaux lives in a trailer on low-lying land but was talking Tuesday morning with a cousin who lived closer to the bayou. They and two friends chatted as the storm approached. Boudreaux laughed when asked what she'll do if the storm hits.
"I'm surrounded by all family," she said, referring to her friends as well as her cousin. "I'll just pick up my little fat feet and run, I guess."
Water may be worse than wind because the storm could push walls of water while dumping rain to flood the low-lying coast in Louisiana, Mississippi, Alabama and the Florida Panhandle.
New Orleans is in much better shape than it was before Katrina with an injection of about $14 billion in federal funds to fix damage done by Katrina and upgrade the system.
The Army Corps of Engineers has spent the last seven years working nearly around the clock to raise levees several feet, install new stronger floodwalls at critical places and strengthen almost every section of the 130-mile perimeter that protects the greater New Orleans area.
The system is built to hold out storm surge of about 30 feet where the city's boundaries meet the swamps and lakes near the Gulf of Mexico.
The improvements include several massive floodgates that are shut when a storm approaches. In particular, a new surge barrier and gate that closes off the Inner Harbor Navigation Canal near the Lower 9th Ward has reduced the risk of flooding in an area long viewed as the city's Achilles' tendon.
Still, there could be problems, especially is Isaac dumps lots of rain on the city.
"I don't really trust the levees," said Robert Washington, who planned to evacuate along with his wife and five children. "I don't want to take that chance. I saw how it looked after Katrina back here."
In Mississippi, beachfront casinos were shutting down late Tuesday morning as beach roads were flooded and residents hurried to shelters.
Farther away on the Alabama coast, Isaac had begun pelting the shore with intermittent downpours — one moment it was dry, and the next brought rain blowing sideways in a strong breeze. Gov. Robert Bentley lifted mandatory evacuation orders for low-lying coastal areas but encouraged residents to remain vigilant nonetheless.
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