The storm has tested the New Orleans' post-Katrina flood defenses, leaving many roads impassable and creating a storm surge from Louisiana to Alabama. NBC's Lester Holt reports.
By NBC News staff and wire reports
Slow-moving tropical storm Isaac was expected to weaken further as it crawled north toward Arkansas on Thursday, but residents in parts of Louisiana were still being evacuated from rising flood waters amid significant damage across the U.S. Gulf Coast.
Protected by federal levees, central New Orleans appeared to have escaped the worst of the storm, but rural areas of Louisiana and neighboring Mississippi were left devastated by lingering heavy rains and relentless winds.
Flood waters up to five feet deep poured into the city of Slidell, on the north side of Lake Pontchartrain, north of New Orleans, early Thursday, emergency officials said.
"Water is currently backing up into the city through Bayou Pattasat," Mayor Freddy Drennan said in a statement on the city's website. "The water levels in Bayou Bonfouca got so high that it has gone around the pump stations into Bayou Bonfouca, and back up into Slidell through that natural drain.
"The pumps are currently unable to pump the water out as fast as it's coming in. It is anticipated that until Bayou Bonfouca recedes, the city will continue to be inundated with water."
About three-quarters of a million homes and businesses across the two states were without power as of 6:30 a.m. ET Thursday, according to information from energy companies Entergy and Mississippi Power.
Carl Parker, hurricane specialist on The Weather Channel, said: "It is a 45-mph storm moving northwest at 8 mph, so widespread wind damage is becoming much less of an issue. But there's a lot of momentum in this system, and it's very slow to spin down.
The $14 billion spent improving Louisiana's levee system did not include the levees near Plaquemines Parish. Residents who decided to stay behind when Isaac hit the region had to be rescued from their flooded homes. NBC's Gabe Gutierrez reports.
“It's still pulling up all kinds of Gulf moisture, producing a large shield of rain. We'll watch the center of the storm slowly move across the state of Louisiana today, with all those impacts being felt across Mississippi."
Federal emergencies
President Barack Obama declared federal emergencies in Louisiana and Mississippi late Wednesday to supplement state and local recovery efforts beginning on Aug. 26, according to a White House statement.
In Plaquemines Parish, a sparsely populated area of south of New Orleans that is outside the post-Katrina federal levee system, dozens were stranded in flooded coastal areas and had to be rescued on Wednesday. Officials rushed to evacuate more than 100 nursing home residents.
Stories from the storm: 'They were screaming away'
The storm pushed water over an 18-mile levee and put so much pressure on it that authorities planned to intentionally puncture the floodwall to relieve the strain.
Along the shores of Lake Pontchartrain just north of New Orleans, officials sent scores of buses and dozens of high-water vehicles to help evacuate about 3,000 people as rising waters lapped against houses and left cars stranded.
The floodwaters "were shockingly fast-rising, from what I understand from talking to people," Lt. Gov. Jay Dardenne said. "It caught everybody by surprise."
/
A downgraded Isaac floods coastal communities and forces new evacuations, but levees still hold.
Isaac arrived seven years after Hurricane Katrina and passed slightly to the west of New Orleans, where the city's fortified levee system easily handled the assault. But, low-lying areas outside the city were harder hit.
"Hurricane Isaac has reinforced for us once again just how vulnerable these critical areas are," Democratic U.S. Sen. Mary Landrieu said.
New Orleans set a daily record of 7.86 inches of rain on Wednesday, The Weather Channel reported, breaking the previous record for August 29th of 4.50 inches set by Katrina in 2005.
NBC News' Danielle Lee, reporting from New Orleans, said: "After 24 hours of relentless wind and rain we're finally getting break here in the French Quarter, some of the worst damage we're seeing are some downed streetlights, some blown out windows and some damaged signs. ... More than 60 percent of the city is without power.
"We're hearing from stores here that they're planning to open later today. You know this area relies on tourism, and they don't want to miss out on that Labor Day weekend travel.
Isaac stirs up horrible memories for New Orleans residents
"I also know the mayor has been calling other stores who are able to sell emergency supplies, generators, things that may help people without power, asking them to please get open as quickly as possible."
Isaac dumped nearly a foot of rain on its desolate streets, but the system of levee pumps, walls and gates appeared to withstand one of the stiffest challenges yet. One person was reported killed, compared with 1,800 deaths from Katrina in Louisiana and Mississippi. And police reported few problems with looting, after New Orleans Mayor Mitch Landrieu ordered a dusk-to-dawn curfew.
Breaking up on weekend?
Forecasters expected Isaac to move farther inland over the next several days, dumping rain on drought-stricken states across the nation's midsection before finally breaking up over the weekend.
Even at its strongest, the storm was far weaker than Hurricane Katrina, which crippled New Orleans in 2005. Because Isaac's coiled bands of rain and wind were moving at only 5 mph – about the pace of a brisk walk -- the threat of storm surges and flooding was expected to linger Thursday as the immense comma-shaped system crawled across Louisiana.
Related: MSNBC anchor's home lost to Isaac
Related: A resident reports from Mississippi town devastated by Katrina
Related: Mississippi coast sees flood damage
In coastal Mississippi, officials used small motorboats Wednesday to rescue at least two dozen people from a neighborhood Isaac flooded in Pearlington. In addition, the National Weather Service said there were reports of at least three possible tornadoes touching down in coastal counties. No injuries were reported.
Back in New Orleans, the storm canceled remembrance ceremonies for those killed by Katrina. Since that catastrophe, the city's levee system has been bolstered by $14 billion in federal repairs and improvements. The bigger, stronger levees were tested for the first time by Hurricane Gustav in 2008.
As hard wind and heavy rain pelted Melba Leggett-Barnes' home in the Lower 9th Ward, an area leveled during Katrina, she felt more secure than she did seven years ago.
"I have a hurricane house this time," said Barnes, who has been living in her newly rebuilt home since 2008. Her yellow house with a large porch and iron trellis was taking a beating but holding strong. "I don't have power, but I'm all right," said Barnes, a cafeteria worker for the New Orleans school system.
As rains poured, Louisiana Gov. Bobby Jindal warned on Wednesday there was "much more coming." He estimated damages to state and local agencies at $24 million as of Wednesday afternoon, according to Nola.com.
The Associated Press, Reuters, BreakingNews.com's David Wyllie and NBC's Alastair Jamieson contributed to this report.
More content from NBCNews.com:
- Isaac's storm surge floods parts of Louisiana, Mississippi
- From darkness to gold: Blinded Navy swimmer set to race at Paralympics
- New York man sentenced to 40 years to life for grisly murder of boy
- California moves closer to banning 'gay cure' therapy for teens
- Baby bobcat injured by California fire recuperating at wildlife shelter
- Two men reunite with wayward boat Queen Bee that washed up in Spain
- Veterans rely on patchwork safety net during hard financial times
