A New Orleans fireman helps evacuate a man out of floodwaters as a home burns in the 7th Ward of New Orleans during the aftermath of Hurricane Katrina, Aug. 6, 2005. The toxic brew of chemicals and human waste in the New Orleans floodwaters will have to be pumped into the Mississippi River or Lake Pontchartrain, raising the specter of an environmental disaster on the heels of Hurricane Katrina, experts say.