What compelled you to make a documentary about Katrina? I just knew that this was going to be an important story in American history. I'm not saying that I have a crystal ball, but when I look back at it … I just think that this is a very important story that Americans want to see. It was very important for me to let the people from New Orleans tell their story, and I'm also very grateful that Sheila Nevins and HBO have given me the platform for it. It's a four-hour documentary, and we're dealing specifically with the Crescent City. We acknowledge that Hurricane Katrina affected all of the Gulf Coast states, but we're dealing with the most unique city, in my opinion, in the United States of America.

We've obviously been bombarded with images of the aftermath of Katrina. How will you provide us with a different perspective than what we've already seen? The media, for the most part, focuses on something and then they let it go. But the people in New Orleans are still living with this today. One of the things that we hope with the broadcast of this film is to get the nation's attention back to New Orleans and the other Gulf states. August 29 marks a year [since this happened]. How much has changed? How much progress has been made? These are questions that I think people would like to have answered.

The outpouring of generosity from the American public was unprecedented, but at the same time, America's attention span is very fickle. I don't want these American citizens to be forgotten. I don't want a great American city to be forgotten. These are not refugees, as they have been called. These are American citizens. There is a big difference between evacuees and refugees. The thing that has really come across to me is the spirit of the people who faced great devastation, great loss of property, and even greater loss of life. Somehow they're able to find humor in it sometimes. In New Orleans, you just stay there. You don't leave your neighborhood. Some people might see that as a negative, but that's how particular people are about their beloved city. These are all the things that we want to convey with this film, this spirit of the people.

What is the one event or situation that you documented that touched or affected you the most during the making of this film? For me, this is a very hard documentary to make. The main reason is that the story changes all the time. 4 Little Girls happened in 1963. This is a living, changing story, so even when we're done and it's delivered to HBO, the story is still not done. This is "to be continued."

Are there going to be images in this documentary that people haven't seen before that might shock them? I think so. We're very frank in showing the devastation. We're not pulling any punches, and because we are on HBO, we can show a lot of stuff that network television can't show.

When the Levees Broke is your 20th feature film in 20 years. Looking back, are you surprised at the longevity of your career? No, it doesn't surprise me because that was a goal from the, beginning - to build a body of work. And you build a body of work by hanging around and learning and growing. When Akira Kurosawa was 80-­something years old, he said there was still a world of cinema that he had yet to learn. And I never want to be in the position where I think I've learned everything and there's no need to learn anything more. I don't want to be like that, that's for sure.