There has been no shortage of filmed analysis of Hurricane Katrina and its aftermath during the last three years. And much of it has been quite good, particularly Spike Lee's sprawling (and riveting) four-hour documentary, When the Levees Broke, which also screened at SILVERDOCS this year. But one doesn't really realize what's missing from these other films until watching Trouble the Water, Carl Deal and Tia Lessin's take on the material, which is both harrowing and inspiring. And while it's Deal and Lessin's film, the special ingredient isn't something that the pair brought to the project themselves: footage from the ground and on the rising waters from the heart of New Orleans' Ninth Ward in the midst of the catastrophe.

For the reels and reels of news footage and professional camera crews roving the streets and newly formed canals of the city in the days following the storm, the most affecting footage comes from an amateur camcorder bought on the street for twenty bucks. The purchaser, Kimberly Roberts, a former small-time drug dealer and aspiring rapper, simply wanted to document family events, but when the storm started to roll in, and she and most of her neighbors were too poor to leave, she had an inkling that the gathering storm might have some historical significance. And, as she said at the Q&A after Friday night's screening, she figured maybe she could sell the footage to the news for some cash after the fact. What she didn't figure on was that she'd end up filming the storm from the perspective of those hit hardest by it at their most desperate moments.

The result is the sort of visceral gut-punch that a movie like Cloverfield aspires to, only without the wealthy and polished youths documenting the disaster. Roberts interviews neighbors as clouds grow thicker in the skies, establishing characters that we'll meet again as circumstances grow dire. The streets begin to fill up with water. It reaches over the tops of stop signs and threatens the residents effectively trapped in her attic after she took in people from the surrounding homes. Roberts continues to film as they float across the street on a heavy bag being controlled by a resident of the taller building next door. Then they run through their meager food supply and eventually having to make an escape to higher ground.

Roberts' footage provides the heart for the film. Deal and Lessin bring to it a pointed commentary (both are veterans of Michael Moore's crew) about the government's reaction, interspersing news footage of Bush and Michael Brown offering empty promises about future relief and pathetic excuses for slow response with footage of what Roberts and her neighborhood were experiencing in real time while the administration was engaged in their PR exercise. It's a damning juxtaposition.

There's more to the story than just the storm and these first life or death moments, though. And the bulk of Trouble the Water deals with the thornier issues of the protracted aftermath faced by so many poor New Orleans residents. Deal and Lessin document the story of Roberts and her husband for months after the tragedy. There's the return to the neighborhood to survey the damage (and to see their eviction notice, present on many neighborhood houses, for repairs). Their interactions with National Guardsmen inspecting the houses in the neighborhood. Trying to rebuild their lives in Memphis, and then again back in New Orleans. The friends and family who didn't make it through the storm, whose departures are sometimes particularly dramatic, and always heartbreaking.

For all the political ramifications of the storm's fallout, the story of Katrina is a human one, and no documentary on the subject yet has hit that point as squarely as Trouble the Water. Kimberly Roberts, her husband, and everyone who comes into their orbit during the course of the movie tell a story that is both entirely unique, and also representative of hundreds of similar stories that could be told by the often ignored members of New Orleans' poorer classes. Their stories are the enduring legacy of the storm and of the great failure of the government to help them in their time of greatest need; a need that is placed squarely in center frame in Roberts' video footage, and that no one who sees this film will ever be able to forget.

SILVERDOCS awarded Trouble the Water with a special jury mention, and has added another screening of the film tonight at 10 p.m. (other award-winning films are also screening tonight as well). The film will begin a theatrical run at the Landmark E Street Cinemas in September.