The situation worsened when levees on four of the city's canals were breached. Storm surge was funneled in via the Mississippi River Gulf Outlet, which breached in multiple places. This surge also filled the Industrial Canal which breached either from the surge or the effects of being hit by a loose barge (the ING 4727). The London Avenue Canal and the 17th Street Canal were breached by the elevated waters of Lake Pontchartrain. Some areas that initially seemed to suffer little from the storm found themselves flooded by rapidly rising water on August 30. As much as 80% of the city—parts of which are below sea level and much of which is only a few feet above—was flooded, with water reaching a depth of 25 feet (7.6 m) in some areas. Water levels were similar to those of the 1909 hurricane; but since many areas that were swamp or farmland in 1909 had become heavily settled, the effects were massively worse. The most recent estimates of the damage from the storm, by several insurance companies, are $10 to 25 billion, while the total economic loss from the disaster has been estimated at $100 billion. Hurricane Katrina surpassed Hurricane Andrew as the costliest hurricane in United States history.