Hang on... I misread that. How much ground water is replaced? Replaced? That's an easy but absolutely unexpected question. Why would you ask such a stupid question? Groundwater replaced? 0 gallons. Groundwater used? Wasn't it somewhere above 1 Trillion gallons a year? The number was in acre/feet. An acre of ground covered by water. Wasn't it like 300 acre/feet? That's a whole lot of water.