NEW ORLEANS — Tropical Storm Isaac, downgraded from a hurricane about 19 hours after making landfall, drove water over a levee in a lightly populated part of Plaquemines Parish, flattened sugar cane 50 miles west in Terrebonne Parish, forced evacuation of a neighborhood in St. John the Baptist Parish and knocked out power to more than 700,000 households and businesses statewide.
State officials were debating whether to make a hole in the low levee at Braithwaite, where dozens of people who had ignored an evacuation order needed rescue, to relieve pressure on the earthen structure, Gov. Bobby Jindal said Wednesday.
Garret Graves, head of the Coastal Protection Restoration Authority, said if a breach occurs it would be in a section of the levee between Braithwaite and Scarsdale so water could flow back into the bay.
"Until those conditions stabilize, it's way too dangerous" to breach the parish levee, Graves said. But he added of the breach, "right now it looks like it will happen."
Parish spokeswoman Caitlin Campbell said an 18-mile stretch from the St. Bernard Parish line at Braithwaite south to White Ditch was taking water and homes were flooding as storm surge piled up against levees between the Gulf of Mexico and the Mississippi River. Civilian volunteers in boats, Louisiana National Guard troops in high-water vehicles and boats and sheriff's deputies from St. Bernard and Plaquemines parishes were going house-to-house.
The Louisiana National Guard brought in 14 high-water vehicles and 10 boats.
"This is a local levee. They knew it's prone to flooding. That's why it was under a mandatory evacuation order. About 20 people or so didn't leave," said Col. Mike Edmonson, superintendent of Louisiana State Police.
"We're going to get out there to them. We're going to do everything we can to get them out of there. But we're not going to put further people in harm's way," Edmonson said.
With the storm expected to be moving across the state for hours, if not days, he said, "This is something we're going to be in for the long haul. This is not anywhere anytime soon."
Wednesday afternoon brought some good news: the storm was weakening more quickly than expected, with peak winds of 50 mph.
Worry about storm surge in Plaquemines Parish prompted a mandatory evacuation Wednesday for the west bank of the Mississippi River below Belle Chasse, where about 3,000 people live.
In St. John the Baptist Parish, the River Forest subdivision was evacuated. The water rose quickly Wednesday, and higher than it ever has, said Brittney Reid. By noon it was creeping into her family's driveway. "Our street will flood, but it's never been in the driveway before," she said. As she was driving her car from the driveway to the higher back yard, "the sheriff came down in a big rescue truck like a paddy wagon," she said.
Isaac bounced off the mouth of the Mississippi River Tuesday night, making its first landfall. It then stalled over Grand Isle, Louisiana's only inhabited barrier island.
Jesse Delcambre, who stayed in the town hall because her fiance is a town employee, said 2 to 5 feet of water covered the island Wednesday morning, and had fallen about 12 to 18 inches by late afternoon.
"The houses over here are all 12, 14 feet above ground on pilings," she said. The few on slabs are flooded, she added.
Jefferson Parish President John Young said 30 to 40 people stayed on Grand Isle, and all were safe. In the rest of the parish, the drainage system kept up with the storm, averting street flooding in all but the usual flood-prone areas, he said.
Grand Isle, a resort prized for its sandy beaches — a rarity in marshy coastal Louisiana — is still recovering from the impact of the 2010 BP oil spill. There were no reports of remnant oil washing ashore.
Still, Young said, he was worried about his communities of Lafitte, Crown Point and Barataria. "We're waiting to see what happens with the Intercoastal Waterway. If it rises 5 to 6 feet we may have challenges there with coastal flooding and tidal flooding."
He wasn't aware of any floods there. "If the wind shifts to the south as expected, we're going to have some challenges."
Plaquemines Parish President Billy Nungesser said part of his roof blew off, leaving his home on the parish's west bank "like standing in a light socket with a fire hose turned on."
Elsewhere, the storm drove sheets of rain through the nearly deserted streets of New Orleans as a population mindful of the powerful punch dealt by Hurricane Katrina seven years ago waited for the storm to get out of their lives. Isaac had stalled along the coast early Wednesday before resuming a move to the northwest several hours later.
Forecasters said the storm could drop up to 20 inches of rain, though city of New Orleans spokesman Ryan Berni said only minor street flooding and fallen trees were reported overnight.
He had no immediate reports of injuries or looting though he said one unoccupied structure had collapsed and there was a fire in a home caused by a candle. "Someone was reading by candlelight and the curtains caught fire," he added.
Thousands of law enforcement officers and Louisiana National Guard troops were poised for possible rescue efforts. Roadways in the city's eastern sector were reported flooded and trees were down.
Across Lake Pontchartrain in Slidell, Public Operations Director Mike Noto asked city residents to flush toilets as little as possible. Sewage tanks were about halfway full without anywhere to pump them, he said.
"This will not affect our drinking water, which we anticipate will remain available throughout the storm," said Noto.
Slidell Mayor Freddy Drennan said most of the city was without power, and conditions were still too dangerous for standby Cleco utility crews to attempt to restore power.
Floodgates were closed on area waterways to block Isaac's storm surge, part of the flood protection system rebuilt with billions of dollars of federal aid after Hurricane Katrina struck seven years ago. Large pumps designed to remove any floodwater from the low-lying level city on the Mississippi River were functioning as planned, Berni said. But he urged residents to remain vigilant and sheltered as long as the winds and rain bands were lashing New Orleans.
"We fully expect people to stay inside and not impede any efforts by our first responders," Berni said.
Entergy Corp. and Cleco Corp. said the 708,000 customers without power included more than 400,000 in the metro New Orleans area, including 47,000 in St. Tammany Parish. More than 83,000 were without power in East Baton Rouge Parish.
"Isaac is testing everyone's patience with its slow movement through south Louisiana," said Bill Mohl, Entergy Louisiana, LLC president and CEO. "We are ready to mount a counterattack to Isaac's onslaught just as soon as the weather conditions allow us to do so."
Though Isaac wasn't packing Katrina's punch, evacuations were mandatory in about a half-dozen parishes.
Coastal communities were largely abandoned after evacuation orders.
Houma, an oil patch community about 30 miles inland, was in darkness after power failed. The center of Isaac was expected to pass over the city as the storm slowly moved inland. Traffic signals swayed amid sheets of wind-driven rain as Isaac lurked nearby. Debris littered roadways.
Associated Press writers Michael Kunzelman contributed to this report from New Orleans, Kevin McGIll from Houma and Melinda Deslatte, from Baton Rouge.