Through my work in coastal zone management, as a founding member of the Gulf of Mexico Alliance, and now in the private environmental and engineering sector, I have been involved with this issue since the late 90's. I am actually working as a senior ecologist on a large project over there now.
The habitat loss in Louisiana is mindboggling. The resources, planning, environmental studies, engineering, sediment sourcing, modeling, etc., that has gone into "fixing" the issue is larger than just about any other habitat restoration issue in this country. The causes are pretty clear and have been known for years: loss of sediment supply caused by levees and dams, combined with subsidence and sea level rise. Salinity changes caused by oil and gas exploration canals as well as the loss of barrier marshes and island is also greatly exacerbating the issue.
Other than whole scale removal of levees and allowing the river to "breathe" and pulse like it did for millions of years, sediment diversions, active marsh building and the beneficial use of dredged materials from navigation projects are the best solutions. Like noted, oystermen and shrimpers don't like the freshwater influx from diversions, but the alternative is, in the long term, we continue to lose thousands of acres of marsh and end up with an ecosystem crash at some point.
No easy answers but LCPRA, LADNR, USFWS, NOAA, EPA, USGS, CRCL,TNC, DU, GOMA, and firms like ours are all working together to come up with projects and get them implemented to slow the loss. But sadly, given the rate that sea level rise is accelerating in the Gulf, I am not sure anything we can do will work in the long run. At some point, many of these low lying areas all around the Gulf will become untenable.
Going to one these conferences is eye-opening:
https://www.stateofthecoast.org/