Officials issued warning for residents in Washington Parish which were followed by nearby Bogue Chitto River was expected to rise by 14 feet overnight. In the meantime, National Guard troops looked for people stranded in St. John Parish after thousands were forced to flee when the surge forced water over the banks of Lake Pontchartrain.
"What we're doing is we have got law enforcement and fire personnel who are going door to door to notify people," Tommy Thiebaud, the Washington Parish director of emergency services, told CNN early Thursday.
The National Weather Service's latest report spotted the eye of the storm 55 miles southeast of Alexandria, Louisiana, early Thursday, moving slowly at about 8 mph with maximum sustained winds of 45 mph.
Isaac reportedly produced a total of three tornadoes overnight in Mississippi and Alabama, the weather service added.
According to CNN, Tornadoes are suspected to be behind the damage in Gulfport and Jackson, while a twister in Geneva, Alabama, is believed to be responsible for damaged homes and knocked down power lines.
President Barack Obama has declared federal emergencies in areas of Louisiana and Mississippi hit hard by Isaac, moving to speed federal aid and recovery efforts to the hurricane-battered Gulf Coast.
Obama signed the orders late Wednesday covering 35 parishes in Louisiana and 34 counties in Mississippi, according to a statement released by the White House.
As of Thursday morning, Isaac Some 840,000 people in Louisiana, Mississippi, Arkansas, Texas and Alabama were without power. Water boiling advisories were also being issued in a number of towns and cities along the Gulf Coast, according to CNN.
Reports from the Louisiana governor's office indicate that about 1,500 people were evacuated from the St. John parish with another 1,500 were expected to leave their homes. In addition, Dozens of buses were used to move residents out of flooded portions of the parish, while authorities worked to rescue others trapped by up to six feet of water.
"We're continuing to rescue people from different areas throughout the parish," Paige Falgoust, communications director for St. John Parish, said early Thursday. "Our main focus right now is getting people out of their homes."
An initial estimate by local Plaquemines parish officials showed as many as 800 homes may have received significant water damage due to a levee in the area that was breached early Wednesday.
With great amounts of water putting pressure on the breached levee, officials were considering intentionally breaching it again downstream to allow some of the floodwater to flow back out of the inundated area, Jindal said.
The intentional breach could happen as early as Saturday, Billy Nungesser, the parish president, told CNN. A report, though, in The Times-Picayune said digging could begin as early as Thursday.
"We are still looking for stranded residents," Nungesser said Wednesday night. "We will resume a double check tomorrow on the homes on the east bank (of the Mississippi River). We're checking the west bank for anyone who may have been trapped," he added.
Reports surfaced late Wednesday afternoon of rescue missions executed In Mississippi's Hancock County, near the Louisiana border. National Guard troops reportedly rescued dozens of people stranded on their roofs and in their attics, by the storm surge.
All roads in and out of St. John Parish were reportedly cut off Wednesday after Isaac's torrential rain and storm surge made the area inaccessible.
CNN reports that Parish officials were cross-matching records to make sure no residents were overlooked as they continued rescue efforts.