IN AUGUST 2005, Imax director Greg MacGillivray (Everest, Coral Reef Adventure) was putting the finishing touches on a film tentatively titled Hurricane Warning. Its topic: Louisiana's vanishing wetlands and how their damaged condition had left New Orleans particularly vulnerable to storms blowing in off the Gulf of Mexico. Then Katrina hit. Within two days, MacGillivray was in the city, shooting footage for what would become a very different movie. Narrated by Meryl Streep, Hurricane on the Bayou follows four musicians who, in the midst of an ongoing public-awareness campaign to save the wetlands, have their lives irrevocably changed by Katrina. Outside's Anthony Cerretani spoke to MacGillivray as he prepared for the film's premiere, August 29 at New Orleans's Entergy Imax Theatre. Hurricane on the Bayou opens in Imax theaters across the country in December.

Outside: Why were you originally drawn to this area of the country?
MacGillivray: The wetlands in Louisiana are bigger than the Everglades and in far more jeopardy. I wanted to show Americans how magical they are—then explain how they're washing away.

And the wetlands and bayous remained your focus, even after hurricane Katrina?
Other documentarians were doing exposés about who messed up in the evacuation efforts. Our story is still about conservation: Had the wetlands not been depleted over the years, they could have absorbed much of Katrina's water—and helped save the city.

To get aerial shots, we heard you borrowed a helicopter from a movie set.
The only helicopter we could find on short notice was the one from Miami Vice. It said MIAMI DADE COUNTY POLICE on the side, so we had no problem getting into places.

Apparently not—your footage is stunning.
The large format captures the scope of the devastation in a way TV news coverage can't. On a big screen, you see 25 boats lifted onto a freeway—or mile upon mile of flooded homes—and you're blown away. The power this storm had sinks in. It's earth-shattering.

What do you hope people take away from the film?
I hope they'll begin to care about the wetlands enough that they'll want to get involved in saving them. They'll go to a Web site or read a book to become more informed about the region. And they'll realize that this is a problem we can all help solve.