NEW ORLEANS (AP) — Isaac soaked Louisiana for yet another day and pushed more water into neighborhoods all around the city, flooding homes and forcing last-minute evacuations and rescues. New Orleans itself was spared, thanks in large part to a levee system built after Katrina.

As the storm slogged its way across the state and windy conditions calmed, the extent of some of the damage became clear. Hundreds of homes, perhaps more, were underwater, thousands of people were staying at shelters and half of the state was without power. About 500 people had to be rescued by boat or high-water vehicles, and at least two people were killed.

And the damage may not be done. Waters continued to rise and a dam at a lake near the Louisiana-Mississippi border was under a lot of pressure and power lines and trees were felled as Isaac moved into Arkansas.

Farther south, evacuations were ordered in a lot of places ahead of the storm, but Isaac's unpredictable, meandering path and the amount of rain — as much as 16 inches in some places — caught many off guard.

"I was blindsided, nobody expected this," said Richard Musatchia, who left his home in LaPlace, northwest of the city.

Musatchia said 5 feet of water filled his home before a neighbor passed by with a boat and evacuated him and his 6-year-old boxer, Renny.

He piled two suitcases, a backpack and a few smaller bags onto the boat and said that's all he has left. He left a brand-new Cadillac and a Harley-Davidson behind.

"People have their generators, because they thought the power would go out, but no one expected the water," he said.

Others trickled into a parking lot of the New Wine Christian Fellowship church, delivered by National Guard vehicles, school buses and pickup trucks.

Daphine and David Newman fled their newly decorate home with two trash bags of clothing. They have lived in their subdivision since 1992, and they never had water in their home from previous storms, including Katrina. The comparison was common one since Isaac hit on the seventh anniversary of the devastating 2005 storm, though the differences were stark.

Katrina was more powerful, a Category 3 at landfall, while Isaac was a Category 1 at its peak. Isaac wobbled around; Katrina barreled into the state and quickly moved through.

David Newman was frustrated the government spent billions reinforcing levees for New Orleans and Jefferson Parish after Katrina and now he had the water.

"The water's got to go somewhere," he said. "It's going to find the weakest link, and with the wind directions, we was ground zero."

As officials called for impromptu evacuations, a debate started about whether anyone was to blame.

Jefferson Parish Council president Chris Roberts said forecasters at the National Hurricane Center needed a new way of measuring the danger. Many second-guessed evacuation orders, he said.

"The risk that a public official has is, people say, 'Aw, it's a Category 1 storm and you guys are out there calling for mandatory evacuations,'" Roberts said.

Hundreds of people in lower Jefferson chose to ride out the storm — and many of them had to be rescued, he said.

Eric Blake, a hurricane specialist at the National Hurricane Center in Miami, said although Isaac's cone shifted west as it zigzagged toward the Gulf Coast, forecasters accurately predicted its path, intensity and rainfall. He did say the storm crept ashore somewhat slower than anticipated.

Blake also said local officials and residents shouldn't use Katrina as a guide for what areas were at the greatest risk of flooding during Isaac.

"Every hurricane is different," Blake said. "If you're trying to use the last hurricane to gauge your storm surge risk, it's very dangerous."

Along the shores of Lake Pontchartrain near New Orleans, officials sent scores of buses and dozens of high-water vehicles to help evacuate about 3,000 people as rising waters lapped against houses and left cars stranded. Floodwaters rose waist-high in some neighborhoods, and the Louisiana National Guard was working with sheriff's deputies to rescue people stranded in their homes.

A Coast Guard helicopter hoisted a couple and their dogs early Thursday from a home in LaPlace, between the Mississippi River and Lake Pontchartrain, after storm surge poured into their neighborhood and local authorities called for help. The couple was taken to New Orleans and reported in good condition.

"The husband and wife and their two dogs were in an area where a lot of houses washed away," said Lt. Cmdr. Jorge Porto. "They used a flashlight inside the house as a signaling device, which made all the difference in locating them effectively."

To the east, evacuations were ordered in a sparsely-populated area as a lake dam threatened to break near the Mississippi-Louisiana border. Officials in Tangipahoa Parish, La., feared the water it would pour into the already swollen river would flood low-lying areas downstream. Louisiana Gov. Bobby Jindal said officials there would release water at the dam.

A tow truck driver was killed Thursday morning when a tree fell on his truck in Picayune, Miss., just across the state line from Louisiana. In Vermilion Parish, a 36-year-old man died after falling 18 feet from a tree while helping friends move a vehicle ahead of the storm. Deputies did not know why he climbed the tree.

President Barack Obama declared federal emergencies in Louisiana and Mississippi late Wednesday, allowing federal aid to be freed up for affected areas.

In southeast Arkansas, winds gusted to more than 40 mph and heavy rainfall fell, knocking down trees and power lines in Chicot County. The small farming town of Eudora lost power. In neighboring Ashley County, a handful of dead trees were scattered across roadways, according to County Judge Emory Austin, who said he was worried about flooding.

"We need the rain, I just don't need a lot," Austin said.

Isaac arrived seven years after Hurricane Katrina and passed slightly to the west of New Orleans, where the city's fortified levee system easily handled the assault.

"Unfortunately, that's not been the case for low-lying areas outside the federal system, in particular lower Jefferson and Plaquemines parishes," said Louisiana Democratic U.S. Sen. Mary Landrieu. "Hurricane Isaac has reinforced for us once again just how vulnerable these critical areas are. We must re-engage the Corps of Engineers on this."

In Plaquemines Parish, a sparsely populated area south of the city that is outside the federal levee system, dozens of people were stranded in flooded coastal areas and had to be rescued. The storm pushed water over an 18-mile levee and put so much pressure on it that authorities planned to intentionally puncture the floodwall Thursday to relieve the strain.

Louisiana's Public Service Commission said 901,000 homes and businesses around the state — about 47 percent of all customers — were without power Thursday. Utility company Entergy said that included about 157,000 in New Orleans.

Officials rushed to evacuate more than 100 nursing home residents Wednesday from Plaquemines Parish, an area with a reputation for residents hunkering down to weather storms and perhaps the hardest hit by Isaac. In this hardscrabble, mostly rural parish, even the sick and elderly are hardened storm veterans.

"I don't think we had to evacuate to begin with," said Romaine Dahl, 59, as he sat in a wheelchair. "The weather was a hell of a lot worse last night than it is now. And I got an idea that after all this is said and done they're going to say everything is over with, go on back home."

Isaac's maximum sustained winds had decreased to 40 mph, and the National Hurricane Center said it was expected to become a tropical depression by Thursday night, meaning its top sustained winds would drop below 39 mph. The storm's center was on track to cross Arkansas on Friday and southern Missouri on Friday night, spreading rain as it goes.

Forecasters expected Isaac to move farther inland over the next several days, dumping rain on drought-stricken states across the nation's midsection before finally breaking up over the weekend.

Isaac came ashore late Tuesday as a Category 1 hurricane, with 80 mph winds near the mouth of the Mississippi River. It drove a wall of water nearly 11 feet high inland.