NEW ORLEANS -- Several viewers have asked us why the big pumps by Lake Pontchartrain weren't turned on during the Aug. 5 flood or any time the streets have flooded in New Orleans.

Investigative reporter Katie Moore explains that those pumps are only used when storm surge forces the Army Corps. of Engineers to close the flood gates. Those pumps then push the water being pumped into the outfall canals OVER the flood gates and into the lake.