Hurricane Ida became a tropical storm as its top winds slowed over Mississippi on Monday, 16 hours after blowing ashore in Louisiana as one of the most powerful hurricanes ever to strike the U.S. mainland. Ida pushed so much water into the mouth of the Mississippi that it reversed the flow of the mighty river and blacked out New Orleans, taking down backup electricity for the city’s crucial pumping system.

Torrential rain kept falling Monday as the storm slowly moved north, with up to two feet (60 cms) expected in places, and reports of flooded roads and homes multiplied. Destructive winds and water already had a catastrophic impact along the southeast coast of Louisiana, and life-threatening river flooding continued well inland, the National Hurricane Center said.

Ida made landfall on the same day 16 years earlier that Hurricane Katrina ravaged Louisiana and Mississippi, and its 150 mph (230 kph) winds tied it for the fifth-strongest hurricane to ever hit the mainland. It was already blamed for one death, someone hit by a falling tree in Prairieville, outside Baton Rouge, deputies with the Ascension Parish Sheriff’s Office confirmed on Sunday.