The Mississippi River runs through Ascension Parish where the sinkhole is located. To give a perspective of how the land lies and the number of people being affected:

Following the Mississippi River, it "is 569 mi from the Arkansas/Louisiana line to the Gulf by river, but only half that in a straight line distance. Over this 569 mi length, its elevation drops 115 ft, or 2.5 in/mi. Rufus LeBlanc, an early expert on the geology of coastal Louisiana, said “No pool (billiard)table is that flat.” "

[link to www.americaswetlandresources.com]