(CBS/AP) NEW ORLEANS - A state official says the levee in southeast Louisiana's Isaac-flooded Plaquemines Parish will be breached to relieve pressure on it.
State Coastal Protection and Restoration Authority head Garret Graves says the levee won't be breached Wednesday because of weather conditions but it will happen as soon as they can get equipment to the site.
In hard-hit Plaquemines Parish, officials rescued dozens of people by boat after they became stranded by floodwaters. Flooding has plagued the area after Isaac sloshed ashore Tuesday evening as a Category 1 hurricane.
Earlier, Isaac was losing some of its strength Wednesday afternoon and had been downgraded to a tropical storm as it rained down on Louisiana. The slow-moving storm, however, has caused severe flooding in many parts of lower Louisiana and coastal Mississippi.
According to a 4 p.m. ET National Weather Service advisory, Isaac had top sustained winds of 70 mph, just below the hurricane threshold of 74 mph, and the storm was about 50 miles west of New Orleans. Thus far, more than 700,000 area residents had lost power due to the storm, and officials say the outages could last for days.
City officials imposed a dusk-to-dawn curfew in New Orleans - as are most of the surrounding local governments - beginning Wednesday because of the downed power lines and generally unsafe conditions.
Forecasters are warning there are still life-threatening hazards from the storm surge and inland flooding.
Earlier, Louisiana Gov. Bobby Jindal had said officials may cut a hole in a levee on the east bank of Plaquemines Parish to relieve pressure on the structure.
The levee officials were considering breaching is on the east bank of the Mississippi River in Plaquemines, reports NOLA.com. That levee runs dozens of miles along the river, and holds it back for a few thousand scattered and mostly poorer residents of the parish.
Jindal said as many as 40 people are reportedly in need of rescue in the area. CBS affiliate WWL-TV reports that 75 people were rescued from flooded homes and rooftops from Braithwaite, La., and that dozens people were still reportedly awaiting rescue on the parish's east bank on rooftops and in attics.
Plaquemines Parish has also ordered a mandatory evacuation for the west bank of the Mississippi River below Belle Chasse, worried about a storm surge. The order affects about 3,000 people in the area, including a nursing home with 112 residents.
Officials said the evacuation was ordered out of concern that more storm surge from Isaac would be pushed into the area and levees might be overtopped.
Earlier, water driven by the large and powerful storm flooded over an 18-mile stretch of one levee in the parish. The levee, one of many across the low-lying coastal zone, is not part of the new defenses constructed in New Orleans after Katrina.
"When this is over, I think we need to check the wind speeds because I lost a good portion of my roof, my fence is down, and water is blowing through the sockets in my house from the back wall," Nungesser said in a phone call to CBS New Orleans affiliate WWL-TV. "That only happened in Katrina."
Plaquemines Parish resident Gene Oddo called CBS affiliate WWL-TV while riding out the storm with his wife and baby girl in their attic Wednesday morning in Braithwaite, La. He said the water level was up to his house's doorframe.
"The water came up so quick," Oddo told WWL-TV. "It looks like we lost everything. If I have to, I may have to shoot a hole in my attic here to get out on our roof, but it looks like the water's not coming up anymore."
Oddo said authorities told him about storm surge going over the levee at around 2 a.m.
"The threat was for flood, which I knew that, and I'd rather be here to save what I can because the insurance doesn't cover all that much," Oddo said.
The first confirmed death attributed to Hurricane Isaac in Louisiana was reported in Vermilon Parish.
Sheriff Mike Couvillon says a 36-year-old man had gone to help two friends move a vehicle from under a tree to prepare for Isaac on Tuesday, and fell to his death after climbing 18 feet up the tree.
Deputies don't know why Carlos Medellin-Guillen of Erath climbed the tree.
He was identified Wednesday after his family was notified.
The accident occurred Tuesday evening shortly before Isaac made landfall to the east on the Louisiana coast.
In Mississippi, the main highway that runs along the Gulf, U.S. 90, was closed in sections by storm surge flooding. At one spot in Biloxi, a foot of water covered the highway for a couple of blocks, and it looked like more was coming in. High tide was likely to bring more water.
In Pass Christian, a Mississippi coastal community wiped out by hurricanes Camille and Katrina, Mayor Chipper McDermott was optimistic Isaac would not deal a heavy blow.
"It's not too bad, but the whole coast is going to be a mess," he said.