Katrina's environmental costs will be high

The headline of this piece is troubling enough: experts say New Orleans now hazardous waste site.

But not until the end of the piece does it become clear that this is not only an immediate threat to those still trapped by the deluge, but a long-term threat to the already fragile bayou ecosystem. A double whammy of destruction that's the natural result of the levee failure and subsequent flooding of the city.

Getting rid of floodwaters so residents can return to their homes is likely to require pumping the dirty water into either the Mississippi River or Lake Pontchartrain, LSU experts said four years ago.

The lake route would kill several thousand acres of nearby swamps and marshes which have already been rapidly diminishing because of alterations to the Mississippi River. But pumping it into the river means flushing it into the delta and the Gulf of Mexico, already suffering from a "dead zone" due to other upriver contaminants.