Correct Response: D. The depletion of the High Plains Aquifer has been caused primarily by water withdrawals for agriculture in a geographic region that does not have sufficient precipitation to recharge the aquifer. Much of the water in the aquifer entered the aquifer during the last ice age when precipitation in the region was greater. There is limited forest cover in the semi-arid High Plains so changes in forest cover (A) are not responsible for the depletion of the aquifer. Although periods of drought have not benefited the aquifer in recent years (B), recent climate change is not the primary cause of the aquifer's depletion. Soil compaction (C) has likely played a very small role in reducing recharge rates in the area, but this is not a significant factor when compared with the tremendous water withdrawals for agriculture.
