I also have my doubts about "negative impact" on the water table, except that a large, deep hole right on the edge of town would tend to fill up with the available ground water and cause a possible shortage. Making them put in deep wells and a water tower is a reasonable request, IMO. But if they plan on processing right there too, then it's a different game. They will likely wash out the gold on site, but after that I have no clue.