Isaac's drenching rains and cooling winds are drifting north of the Gulf Coast, leaving in their wake thousands of people displaced by floodwaters.

In Louisiana, more than 400,000 sweltering electricity customers are still without power, days after the storm dragged through the state.The number without power is down from more than 900,000.

However, John Young, president of heavily populated Jefferson Parish, near New Orleans, has been highly critical of Entergy Corporation's restoration efforts. The company says it's doing the best it can while ensuring the safety of workers.

The beginning of the U.S. Labor Day holiday weekend began what was certain to be a slow recovery for Louisiana, though there were signs of life getting back to some sense of normalcy Friday. The Mississippi River opened to limited traffic, the French Quarter rekindled its lively spirit and restaurants reopened.

Isaac dumped as much as 41 centimetres of rain in some areas, and about 500 people had to be rescued by boat or high-water vehicles. More than 5,000 people were still staying in shelters.

The remainder of the storm was still a powerful system packing rain and the threat of flash flooding as it headed across Arkansas into Missouri and then up the Ohio River valley over the weekend, the National Weather Service said.

Farther south, the storm victims included a man and a woman discovered late Thursday in a home in the hard-hit town of Braithwaite, south of New Orleans; a man killed in a restaurant fire; two men killed in separate car accidents and a man who fell from a tree.

'So far operations seem to be proceeding as expected, and they seem to be working.'—Louisiana Gov. Bobby Jindal

Isaac's death toll is now at least seven — five in Louisiana and two in Mississippi. It includes a 75-year-old Slidell, Louisiana man who drowned after his car fell from a flooded highway up-ramp into almost three metres of water Thursday evening. Mississippi authorities have confirmed that the death Thursday of a 62-year-old woman whose car was hit by a tree has also been attributed to Isaac.

Presidential candidates head to flood-hit areas

Newly-nominated Republican presidential candidate Mitt Romney visited flood-ravaged communities, and President Barack Obama said he would arrive Monday, appearances this part of the country is all too familiar with after Katrina and the Gulf oil spill.

Meanwhile, the leftovers from the storm pushed into the drought-stricken Midwest, knocking out power to thousands of people in Arkansas. At least six people were killed in the storm in Mississippi Louisiana.

In Lafitte, a fishing village south of New Orleans, Romney saw soaked homes, roads covered with brown water and debris-littered neighbourhoods. The Republican-friendly community is outside of the federal levee system that spared New Orleans and it lay on an exposed stretch of land near the Gulf.

John Henry, a biologist with the Louisiana Department of Wildlife and Fisheries, rescues a fawn after Hurricane Isaac in La Place, Louisiana on August 31, 2012. John Henry, a biologist with the Louisiana Department of Wildlife and Fisheries, rescues a fawn after Hurricane Isaac in La Place, Louisiana on August 31, 2012. (Jonathan Bachman/Reuters)

Crown Point, Lafitte and other nearby settlements that jut inland from the Gulf are accustomed to high water driven by hurricanes. But Isaac, a relatively weak storm by the standards of Betsy and Katrina, pushed in much more water than expected after it stalled after landfall.

To the east, officials pumped and released water from a reservoir, easing the pressure behind an Isaac-stressed dam in Mississippi on the Louisiana border. The threat for the earthen dam on Lake Tangipahoa prompted evacuations in small towns and rural areas.

"So far operations seem to be proceeding as expected, and they seem to be working," Gov. Bobby Jindal said.

More than 15,000 utility workers began restoring power to customers in Louisiana and Mississippi, but officials said it would be a couple of days before power was fully restored.

Crews intentionally breached a levee that was strained by Isaac's floodwaters in southeast Louisiana's Plaquemines Parish, which is outside the federal levee system. Aerial images showed the water gushing out. Gov. Jindal said officials expected 70 per cent of the water on the east bank to disappear because of the release and changing wind direction.