New Orleans may be the victim of a one-two punch as Hurricane Isaac threatens to strengthen over the Gulf of Mexico and the ongoing effects of this summer’s drought continue to trickle down to the Delta. The record temperatures and lack of rain that have devastated crops in America’s heartland upstream also have weakened the once-mighty Mississippi River’s defenses against saltwater intrusion.
Freshwater flowing south from the Mississippi and salty water from the Gulf are constantly arm wrestling for territory in the Mississippi River Delta, where the river dumps into the sea (see map). But as dry weather shrinks the Mississippi, the Gulf is gaining ground, pushing more saltwater inland. At risk is New Orleans’ freshwater supply.