The flood gates in New Orleans' were closed Tuesday morning for the first time since they were built after Hurricane Katrina seven years ago. The Army Corps of Engineers shut down the inner harbor canal to protect against rising water and anticipated storm surge from incoming Hurricane Isaac. The gates are part of a one-point-eight mile barrier designed to protect New Orleans and St. Bernard Parish. Isaac is heading northwest through the Gulf of Mexico towards the mouth of the Mississippi River. It's expected to make landfall Tuesday night as a Category One hurricane with winds exceeding 74 miles per hour.