(CNN) -- A weakened Isaac moved over Arkansas Friday, leaving weary residents in Southern states digging out of its muddy mess and hundreds of thousands without power.
The weakened storm, now a tropical depression, is expected to move over southern Missouri later in the day after slamming the Gulf Coast as a powerful Category 1 hurricane Tuesday.
Isaac packed a punch as it crawled inland. At three people were dead and more than 827,000 customers were without electricity across Arkansas, Alabama, Louisiana and Mississippi as of late Thursday, utility companies said.
It made landfall on the anniversary of Hurricane Katrina, which devastated Louisiana seven years ago. That deadly hurricane churned through the Gulf of Mexico and overwhelmed levees, resulting in 1,800 deaths.
"This is unbelievable. Deja vu, man," Billy Nungesser, the president of Plaquemines Parish, Louisiana, said Thursday as he surveyed Ironton town, which was inundated by floodwaters and sludge. "There is more water here than Katrina."
Parish officials intentionally breached a levee in the parish to help drain floodwaters in nearby communities.
The bodies of a man and woman were found in 7 feet of water in the kitchen of a home in the parish, officials said late Thursday. An autopsy will determine the cause of the death of the couple, described as being in their 40s, Nungesser said.
In Tangipahoa, Parish President Gordon Burgess called for a mandatory evacuation for those living within a half-mile of the Tangipahoa River. Louisiana Gov. Bobby Jindal said the move was a precaution because if the dam were to break, it would only take 90 minutes for floodwaters to get to Kentwood, a town of about 2,200 residents.
Twenty-eight Louisiana parishes were under a boil-water advisory, health officials said.
In Mississippi, the storm had a "major impact," Gov. Phil Bryant said. A tow truck driver attempting to clear debris on a road was struck and killed by a falling tree, officials said.
An earthen dam on Lake Tangipahoa in Mississippi was holding its own and not leaking late Thursday, despite significant damage, according to the Pike County Emergency Management Agency.
Agency director Richard Coghlan said a "controlled breach" or spillway will be created at Percy Quin State Park's lake to relieve pressure and drain it.
Crews were working carefully overnight, moving in equipment to prepare for the operation expected to commence later Friday.
As Isaac moved into southern Arkansas, it brought the possibility of flash flooding and tornadoes.
"It's looking more disorganized, but it is still putting out quite a bit of rain," said Charles Dalton, a National Weather Service meteorologist in Little Rock.
Rainfall around Little Rock could total 5 inches by Friday, he said. Higher amounts were expected in southeastern Arkansas. Emergency crews are also trying to restore power to many.