The storm that had been Hurricane Isaac swirled into the central US on Friday, leaving behind a soggy mess in Louisiana.
Neighbourhoods were underwater and even homes that stayed dry didn't have lights, air conditioning or clean water.
It will be a few days before the soupy brown water recedes and people in flooded areas can return home.
New Orleans itself was spared, thanks in large part to a levee system fortified after Katrina devastated the Gulf Coast in 2005.
The city lifted its curfew but was hardly back to normal.
"I have a battery-operated fan. This is the only thing keeping me going," said Rhyn Pate, a food services worker who sat on a porch with other renters. "And a fly swatter to keep the bugs off me - and the most important thing, insect repellent."
The heat was getting to Marguerite Boudreaux, 85, in Gretna, a suburb of New Orleans.
"I have a daughter who is an invalid and then my husband is 90 years old, so he's slowing down a lot," she said, red in the face from the lack of air conditioning in her house.
Isaac dumped as much as 16 inches of rain in some areas, and about 500 people had to be rescued by boat or high-water vehicles. At least two deaths were reported.
Crews intentionally breached a levee that was strained by Isaac's floodwaters in southeast Louisiana's Plaquemines Parish.
At the same time, water at a dam farther north in Mississippi was released in an effort to prevent flooding there. Aerial images showed water gushing out of both.
In Louisiana alone, the storm cut power to 901,000 homes and businesses, or about 47% of the state.
That was down to 39%,or about 821,000, by Thursday evening, the Public Service Commission said.
More than 15,000 utility workers began restoring power to customers in Louisiana and Mississippi, but officials said it would be at least two days before power was fully restored.
On Grand Isle, a barrier island on the Gulf, the town pumped away water and sections of the only road in had washed out.
On a street turned river in Reserve, on the east bank of the Mississippi River, two young men ferried neighbors to the highway, using boards as paddles.
Lucien Chopin, 29, was last to leave his house, waiting until his wife and three kids, ages 7, 5 and 1 were safely away. His van was underwater and water flowed waist-high in the house he'd rented.
"It's like, everything is down the drain. I lost everything. I've gotta start all over," he said.
Cisco Gonzales, a heating and air conditioning business owner, said he got his boat and truck and headed for higher ground when he heard the water was rising quickly, to 6 feet (2 meters) of water in five minutes.
"I've never seen so much water in my life," said Gonzales, who built a home in Braithwaite, southeast of the city, after his previous home was damaged by Katrina in 2005.
He rode out the storm at a ferry landing and when the weather calmed, he went out and rescued about a dozen people.
Isaac hit on the seventh anniversary of Katrina, a hurricane that devastated New Orleans.
The two storms had little in common.
Katrina came ashore as a Category 3 storm, while Isaac was a Category 1 at its peak. Katrina barreled into the state and quickly moved through.
Isaac lingered across the landscape at less than 10 mph and wobbled constantly.
Because of its sluggishness, Isaac dumped copious amounts of rain. Many people said more water inundated their homes during this storm than during Katrina.
Both storms, however, caused the Mississippi River to flow backward.
And both prompted criticism of government officials - in the case of Isaac, officials' calls for evacuations so long after the storm made landfall caused some consternation.
Eric Blake, a specialist at the hurricane center, said although Isaac's cone shifted west as it zigzagged toward the Gulf Coast, forecasters accurately predicted its path, intensity and rainfall.
He did say the storm came ashore somewhat slower than anticipated.
Blake cautioned against using Katrina as a benchmark for flooding during other storms.
"Every hurricane is different," Blake said. "If you're trying to use the last hurricane to gauge your storm surge risk, it's very dangerous."
In Mississippi, several coastal communities struggled with all the extra water, including Pascagoula, where a large portion of the city flooded and water blocked downtown intersections.