<P> Just as matters were beginning to improve in 2010, the Deepwater Horizon oil spill in the Gulf in April 2010 caused massive amounts of oil to come ashore in the wetlands and marshes in Plaquemines Parish and other areas of coastal Louisiana near New Orleans that had been most heavily damaged by Katrina, and the spill will likely reach other states that were also affected by the storm (the hurricane had caused or exacerbated oil spills on a smaller scale when it hit). </P> <P> Mayor Ray Nagin did not order a mandatory evacuation of the city until August 28, 2005 . Approximately one million people had fled the city and its surrounding suburbs by the evening of August 28, while about 100,000 people remained in the city, with about 10,000 taking shelter at the Louisiana Superdome which had been prepared to accommodate only 800 . Eventually, 30,000 arrived at the Superdome before they were evacuated . </P> <P> By August 31, eighty percent (80%) of the city of New Orleans was flooded by Hurricane Katrina, with some parts of the city under 20 feet (6.1 m), of water . Over 50 breaches in region's levee system were catalogued, five of which resulted in massive flooding of New Orleans . The 17th Street Canal levee was just south of the Hammond Highway Bridge . Levees adjacent to London Avenue breached in two locations: one near Robert E. Lee Boulevard and one between Filmore Avenue and Mirabeau Avenue . Two breaches also occurred in the Industrial Canal adjacent to Surekote Road . Levee repair efforts were undertaken, involving reinforcing the levees with 3,000 pounds (1,400 kg) sandbags deployed by U.S. Army Chinook and Black Hawk helicopters . The 17th Street Canal levee repair was completed by September 5, 2005 and subsequently, the three canals were repaired all the way to Lake Pontchartrain . The Army Corps of Engineers added flood gates to the three canals . </P> <P> Many evacuees were trapped in flooded houses and rooftops waiting to be rescued . The Superdome sustained significant damage and much of the dome's waterproof membrane had essentially been peeled off . On August 30, Louisiana governor Kathleen Blanco ordered the complete evacuation of the remaining people that sought shelter in the Superdome . Blanco instructed the Adjutant General of the Louisiana National Guard, Major General Bennett C. Landreneau to contact Honoré of Northern Command (Honoré arrived on Wednesday, August 31, as the commander of the newly established Joint Task Force Katrina to supervise federal military operations) to arrange for active duty military support of response operations in Louisiana . Additionally, General Landreneau instructed Louisiana National Guard officials at the Superdome to cease planning for the evacuation as Honoré would be "taking charge" of the evacuation project . The evacuees were then transported to the Astrodome in Houston, Texas . The only route out of the city was west on the Crescent City Connection as the I - 10 (twin span) bridge traveling east towards Slidell, Louisiana had collapsed . The Lake Pontchartrain Causeway was also carrying emergency traffic only . </P>

Where did katrina hit the hardest in new orleans