Residents hunker down in New Orleans

>> us to lester holt , also in new orleans . lester, if we have a storm moving north at eight miles an hour, carrying this much of rain, we're about to see what $14 billion worth of improvements bought there in new orleans ?

>> reporter: you bet, all those pumps, all the strengthened levees, this will are a big test as we see in the coming hours. the mayor of the city believes they've done all the preparations they can, he says we're now in hunker down mode here. there's not a person in this city that doesn't know what's at stake. katrina cost them 1,400 lives. it cost $135 billion in damage. even as a category one, this storm has great potential to put lives at risk. just hours before the rain and wind of isaac 's leading edge rolled into town. engineers for the first time in the face of a real hurricane closed this massive new flood gate , pulling the trigger on a billion dollar post katrina project to protect new orleans from an expected storm surge of up to 12 feet.

>> we feel like we're in pretty good shape. we don't know yet. but we're not out of the hunt. we have to stay in the fight, until we're finished.

>> reporter: the streets of downtown new orleans were virtually empty today, as most heeded the warning to take shelter at home. many confident the city could handle isaac .

>> if you live in a levee protection zone, you're all right. outside of that levee protection zone, then you're all right. outside of that levee protection zone, then you have to worry about the ward.

>> reporter: others fatalistic.

>> mother nature is a tricky thing. i don't care what you do, if she want to come get you, she going to come get you.

>> reporter: a staging ground for some of the thousands of national guards troops ready to assist in rescues and recovery.

>> it's jockeyed a little bit.

>> reporter: just south of new orleans in plaquemines parish , officials are watching the latest storm surge predictions, knowing despite a last minute effort to reinforce earth and levees, it will be a close call .

>> i have five feet here, and eight feet here.

>> it looks like it's going to come in below that.

>> that's where we need it to be. the only threat then, if it continues for a long period of time, we'll see some deterioration.

>> reporter: still, the risk to the levees will be overtop. it was high enough to forsman de tory evacuations for parts of plaquemines and other high risk areas. many evacuees woke up in shelters this morning, hoping their nightmares of 2005 aren't about to be repeated.

>> i'm just hoping it's not bad, and we do have something to go back home to. because i'm not looking forward to going through katrina .

>> reporter: tonight for the people and government of this region, a clock on preparing for isaac has run out. he's here. tonight at least 10,000 people are without power, customers without power here in louisiana, also folks in mississippi and alabama, suffering through this. brian, the coast guard has declared conditions zulu here on the mississippi river . all traffic has been stopped, all ports are closed.

>> all that real estate you showed us, lester, harbors a lot of memories. we'll be thinking of everybody as they go through this long night. lester holt in new orleans .

>>> thanh truong is on the beach in gulfport, mississippi, and