( a chronic issue to the health of the ci...)Toxic flood lifts lid on common urban pollution problem

He said the contamination in New Orleans also highlights the need for other cities nationwide to do more to remove the toxins in urban runoff before, rather than after, it gets washed into waterways. There are several good strategies, he said. Increasingly affordable "permeable pavements" allow runoff to be stored, evaporate or percolate through pavement and into the ground, where soil and microorganisms can help filter the contaminants. Planting vegetation and especially trees also creates aesthetically pleasing buffer zones, providing storm water flooding control and other benefits. Finally, cities can use high-tech street sweeping equipment that is very effective at capturing pavement contaminants.

"If you pick up this potentially toxic material before it gets into the hydrological cycle, it is far more economical than if you try to take it out of the water after the fact," he said.