The only place that would hold puddle ducks (for the most part) are areas with brackish or fresh water like the marshes. They don't allow airboats in there. I think what makes a bigger matter of the deal is boats overall. I know I am going to get flamed but I don't care. I cut my teeth hunting the quadalupe delta. Back in the day you would only see one boat in the whole delta. They didn't jack with you and you didn't jack with them. The last time I was down there I was sickened as to what this sport has turned into, people leaving trash. People lined up the shoreline stepping on each other. One group of DB would shoot if we had birds working into our decoys. I just said to heck with it and left. There was so much traffic in there the birds would not stay.
My other thought of a reason is the widgeon grass. The delta used to get flooded (Flushed) quite regular. AS the 10 year drought trudged on, the grass in the marshes I was hunting would not grow. Even the cane all died out. It was no longer even brackish water, it was pure salt water. That could have been a factor besides my "too many" boat theory. It could be both. I agree things have dropped severely down there. Thank God for a redhead duck