I doubt very seriously that you have the cotton-mouth infestation that you think you do. You're most likely only seeing various water snakes. Where do you live in Rockwall? Chances are, considering I was born and raised there, that I'll know of the pond you're talking about. I'm not saying that you don't have any CM's in you pond, I'm only saying that most people mis-identify them 99% of the time. If you have beneficial non-poisonous water snakes at your place then you'll be much better served to leave them alone because they compete with non-beneficial poisonous snakes like the ones you're trying to avoid. On a CM look for a wide flat body. Usually in Rockwall County they're practically solid black. They have an arrow shaped head. You usually never see one over 24" long and their tail will taper off sharply. When they swim, their entire body is on the surface as opposed to just their head. Be careful with any snake that you've not identified, but usually you're not going to have any problems.
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what we need is another Joseph McCarthy