we've given a shit for the past 25+ years.
no one has cared until recently, and they still don't for the most part.
Basically after the 192X flood of New Orleans, the Army Corps built levees all the way to the mouth.
They've kept the river from shifting channels (to the Atchafalaya River) and have forced it's rich waters off the continental shelf. These waters used to replenish marsh, but they can't do that when that's the case.
Then when oil drilling became big in the 50s down here, canals were cut all over the marshes and basically exposed them to saltwater intrusion and increased erosion (more areas exposed to open water).
It's really, really really sad.
We've lost some 3,400 sq. miles of coast over the past century.