Ida's surge caused the Mississippi River to flow backwards. From a forward flow of ~330,000 to a reverse flow of ~40,000 cubic feet per second.

https://waterdata.usgs.gov/nwis/uv?cb_00060=on&cb_00065=on&cb_63160=on&cb_63680=on&cb_72255=on&format=gif_default&site_no=07374525&period=&begin_date=2021-08-23&end_date=2021-08-29