On Monday, August 29, 2005, the Gulf Coast of the United States was hit by the sixth most destructive Atlantic hurricane on record, Hurricane Katrina. Katrina formed in the Bahamas on August 23 and entered the Gulf of Mexico two days later, on the twenty-fifth (Knabb 2005). Twelve hours after entering the gulf, Katrina grew from a Category 3 to a Category 5 storm on the Saffir-Simpson scale, with winds up to 160 miles per hour. Katrina made landfall on the twenty-ninth as a powerful Category 3 storm with winds up to 145 miles per hour. However, once Katrina made landfall she maintained a storm surge equivalent to a Category 5 storm. For the city of New Orleans, the greatest threat without question was to be from the storm surge. Lake Pontchartrain—which normally sits at one foot above sea level—was elevated to eight and a half feet above sea level. On Tuesday, August 30, the city's levees broke in three places—along the Industrial Canal, the 17th Street Canal, and the London Street Canal (Mihelich 2005). As a result, 80% of the city was flooded, in some places with water as high as 20 feet above sea level (Knabb 2005).