The 1915 hurricane is thought to have been a category 4 storm that crossed over Grand Isle and missed New Orleans by 20 miles to the west. The surge up the river overwhelmed the river levees downstream from the city. Catastrophic flooding extended as far up river as Myrtle Grove.

New Orleans experienced 80-90 mph sustained winds with gusts to 120. Surge in the lake caused flooding across the entire lakefront particularly along the navigation and outfall canals. Water flooded into the central city bowl. However in 1915 there wasn't much development along the lakefront and the central bowl was still mostly undrained swamp. St. Bernard, and the lower ninth were unaffected. Water remained in the city for four days until power could be restored to the pumps.

As a result of this storm levees were built along the outfall canals and along the lakefront. Pumping station investment intensified as the Wood Screw Pump proved reliable and capable of draining the city.


Sewerage and Water Board Report

Wikipedia report

Another storm in 1909