Isaac strains New Orleans defences
HURRICANE ISAAC howled through Louisiana and Mississippi yesterday, sending flood waters surging over a rural levee and straining New Orleans's defences on the anniversary of Hurricane Katrina. However, the US National Hurricane Centre said it had weakened to a tropical storm by 3pm east US coast time yesterday.
Earlier, Isaac unleashed sustained deluges and winds of 121km/h as it moved slowly towards New Orleans, knocking out power to more than 600,000 homes and stoking concern about flooding in the city overnight.
Families in Plaquemines parish, a low-lying district just south of New Orleans, were evacuated from rooftops and attics after water poured over a 2.5m levee and smashed its way into homes.
The state governor, Bobby Jindal, said the levee may have to be "intentionally breached" to drain the rising waters.
Rachel Rodi, an army corps spokeswoman, said the city's levees, fortified after the 2005 catastrophe, were withstanding Isaac's battering.
"The system is performing as intended, as we expected. We don't see any issues with the hurricane system at this point."
However, Isaac's crawl - it wobbled inland at 10km/h - dumped torrents of rain on to the same area, in some places more than 20 inches.
"We're down to a differential of 7ft between the levee and the tide," said Windell Curole, manager of the levees and flood gates in Lafourche, just south of New Orleans.
"If the storm continues moving so slowly we could be down to a differential of two or three feet and that's way too close for comfort; that's when all sorts of bad things can happen."
The problem was not so much Isaac's ferocity but its dawdling pace, said Mr Curole. "Because it's stalled it's become more of a problem than we anticipated."
The Hurricane Centre later downgraded Isaac to a tropical storm after it gradually weakened as it moved further inland.
Isaac was crueller to the fishing community of Plaquemines, Louisiana, where it flooded a 29km stretch of one levee - not part of the New Orleans system - triggering the rescue of about two dozen people who had defied a mandatory evacuation order.
The US National Guard mobilised to rescue hundreds more as water levels rose.
"If that's a category 1 storm, I don't want to go through anything stronger," the parish president, Bill Nungesser, told a press conference. "We've had a breach, 12-14ft of water in homes and businesses over there, and there's a lot of people that need to be rescued.
"There's over 25 people that have called into the fire department that are in their attic, on their roof, waiting to be rescued. No one thought this storm was going to do what it did to Plaquemines parish.
"I myself have more damage from this storm than Katrina," he said.
There were no initial reports of casualties.
The levees in New Orleans - part of a $14.5 billion (€11.6 billion) flood defence system erected after Katrina, which caused some of the worst structural damage in US history - were last night withstanding the onslaught which began after Isaac made landfall on Tuesday night near the mouth of the Mississippi river.
- (Guardian service)