Isaac to test levees in area hit by Katrina

>> bit. nbc's lester holt 12 miles outside of downtown new orleans in belle chasse , louisiana . good morning to you.

>> reporter: savannah, good morning. dozens of families spent the night in the auditorium behind me, one of the shelters put in place here for those part of a limited mandatory evacuation. here is why. if you look at the map of louisiana that finger that sticks out in the gulf, that's where we are, plaquemines parish . the mississippi river runs up the middle. the levees on the side, some built up since katrina . the others simply aren't strong enough to hold back the storm surge they expect here later today. the approaching storm is called isaac, but it's the legacy of katrina that sent many fleeing to higher ground .

>> that's why i'm leaving, me and my grandbaby. i can get another house, vehicle but i can't get another life.

>> reporter: plaquemines par ickes where katrina came ashore seven years ago. vulnerable then and parts of it vulnerable for now. cars lined up for the ferry to cross to the east shore of the mississippi to relatively safer ground just hours after a mandatory evacuation order took effect.

>> they are on edge. this is a big storm. nothing like katrina . but the whole south end of this parish was under water and people were kept out for months.

>> in new orleans, devastated lower ninth ward, the scene of bitter misery in 2005 and where a slow rebirth had finally begun to take hold. many of those new homs built by actor brad pitt and residents boarded up. it now sits behind stronger and higher levee walls along with flood gates and better pumps. this time the system will hold.

>> we've rehearsed, "we've checked out our systems and we're comfortable with our preparations.

>> but lisa haywood would be comfortable sitting out the storm elsewhere. she and her family decided on her own to evacuate.

>> i have faith in god. i don't have faith in those walls.

>> reporter: the uncertainty of isaac's landfall has left them uncertain. states of emergency from louisiana to florida. you'll be hard pressed to find water or batteries this morning in places like gulf shores , alabama and equally hard pressed to find someone in mississippi who doesn't have a harrowing tale of hurricane katrina .

>> the day before katrina i owned three houses. the day after katrina i was homeless.

>> for hundreds of miles the rituals of impending disaster, boarding up homes, topping off gas tanks and waiting.

>> the message for our citizens is not to take this lightly.

>> and around here, that is the enduring lesson of katrina .

>> yeah i fear all storms. you never know what you're going to get.

>> about 7,000 people here in plaquemines parish are part of that limited mandatory evacuation. but the city of new orleans , they have great confidence in that new system of levees. no mandatory evacuation there. savannah, they told folks to shelter in place and hunker down. as al said, this one is going to take a while to pass.

>> lester holt , so many bad memories. thank you so much.