While Isaac lost its hurricane status Wednesday afternoon, officials warned of continued life-threatening hazards from storm surges and local flooding.
Earlier Jindal said a first estimate from local officials in the parish showed as many as 800 homes may have received significant water damage. The U.S. Army Corps of Engineers reported significant storm surge in the parish, scene of many rescues.
One involved National Guard troops who moved 112 residents from the Riverbend nursing home to another facility.
Dozens of Louisiana families that had ignored mandatory evacuation orders in a low-lying area retreated to their attics and roofs and sought rescue amid the howling wind and pounding rain.
Mississippi Gov. Phil Bryant said Wednesday that 34 people were rescued by boat in Hancock County, on the coast northeast of New Orleans, and 15 others were picked up by National Guard troops in trucks. CNN affiliate WWL reported major flooding in LaPlace, west of New Orleans.
Isaac threatened to keep churning over the region for another day.
The punishing storm conditions will persist "all day today, into tonight, into tomorrow," said Richard Knabb, director of the National Hurricane Center.
A volunteer in the St. John the Baptist Parish sheriff's office said more than 200 residents in LaPlace, about 25 miles northwest of New Orleans, had been rescued from rising water coming from Lake Pontchartrain.
The region's largest power provider, meanwhile, told customers to prepare for "extended power outages." Overall, power companies said more than 817,000 customers were without power in Louisiana, Mississippi, Alabama, Florida, Texas and Arkansas. More than three-fourths of the outages were in Louisiana.
Sixty road segments in Louisiana were closed as of Wednesday afternoon, officials said, including the Lake Pontchartrain Causeway.
"We are trying to keep priority routes open as much as safely possible," said spokeswoman Amber Leach of the Louisiana Department of Transportation and Development.
As of 7 p.m. CT, Isaac's maximum sustained winds were at 60 mph.
The storm's center was about 30 miles south of Baton Rouge and about 60 miles west of New Orleans, the hurricane agency said. Police officers said the city will be under a dusk-to-dawn curfew beginning Wednesday evening.
Isaac was creeping to the north at only 5 mph, giving it a long time to inflict damage.
Jindal said there was a report of a fatality in a fire early Wednesday, but officials had not confirmed the report.
Officials were quick to emphasize that the huge federal investments in recent years to avoid a repeat of Hurricane Katrina's horror had worked in New Orleans.
"The system that the country invested in is absolutely paying off," said Louisiana Sen. Mary Landrieu.