That entire area is an extremely shallow area with a flat muddy bottom. Its also surrounded by an area of Marsh and Swampland. This is the estuary that gives birth to some of the best shrimping around. It ALSO gives the area a very brown and usually muddy water. The shallow, flat and muddy bottom extends further offshore
to the continental shelf (from the Texas-Louisiana border) further than anywhere in the US
There can of course be effects from the oil
industry but even without that its never going to be Caribbean
clear. However, just offshore
(over 100 miles) is the Flower Gardens Marine
Sanctuary. This is the Northern-most coral
reef in the Northern hemisphere. I once dove there with over 300 foot visibility under water.
Welcome to Flower Garden Banks National Marine Sanctuary
There are many reasons to like or dislike the area, but the muddy water is not a major one.
Just my opinion of course.