In the Gulfport Biloxi area you aren't actually in the Gulf until you are beyond the barrier islands. Mississippi Sound is the body of water between the shore and the islands and it is brown from the local rivers that empty into it. The Gulf waters beyond the barrier islands can be almost the same as Gulfshores, Ala. or Pensacola
As I recall, that was one of their explanations. The barrier islands prevented the tidal action from cleaning the waters near the shore, and pretty much just blocked in the gunk stirred up by the hurricane. I was there from late 1977 through early 1978, and the detritis washed into the sound by Camille was still presenting some significant health hazards. Dead fish regularly washed ashore, though on warm days it still wasn't unusual to see loads of people swimming from the beaches.
From the sounds of it, the water there might not be much prettier, but probably not as unhealthy as they were back then.