The Atchafalaya Basin

From the U.S. Geological Survey (USGS):

Further south along the Atchafalaya River begins the largest wetland and swamp in the country, the Atchafalaya Basin. This is a delicate ecosystem, made up of cypress swamps in the north and saltwater marshes in the south. 

As the floodwaters move in, they stir up the existing system, overflowing banks, lifting sediments from the bottom, adding nutrients and dissolved oxygen to areas that aren't used to them, etc.

The Basin is used to these regular floods. In fact, just like forests in the West needing regular forest fires, the Basin needs regular floods to maintain its healthy ecosystem.

However, also like western forests, human activity has altered the Basin, so the regular flooding can result in unintended side effects, like extra nutrients causing low oxygen zones (hypoxia). This can lead to fish kills.

Image shows a cypress swamp near Bayou Pigeon, Louisiana. Image credit: Alex Demas, USGS, on Thursday, January 14, 2016. #USGS #Science#2015flood #flooding #Louisiana