There is a man and wife that have an offshore helo company near the Tx. coast in flat, nearly marsh area. He had a pond built and a windmill put right at the shore of the pond. Sounds lake a similar situation as yours. It stays pretty much full. Always a good breeze and no trees to stop it, though. Let the grass grow. When is is covered with water, it will harbor critters to feed the fish. I know it can get pretty unsightly in a hurry, though. There are much cheaper glyphosate herbicides than roundup. 2-4-D is another option.
