Please don't drown an animal, that is a horrible way to die. Everyone, please don't get mad at me for saying that, I'm not saying that eliminating predators is bad... but I think there are more humane ways to do it (such as a head shot).
I don't think mothballs really work, your best bet is to block the entry or trap and remove. We had a skunk living under our shed and he kept spraying our house. I finally called a local wildlife trapper to remove him. If you can set up a trap, cover it it with a cardboard box and cut a hole in the top for the trap handle. Then call your county animal control when the skunk is in the trap and they will probably come pick it up. Even if the skunk sprays the cardboard cover, it can't stink any more than his repeated sprayings of your house!
Good luck!