Which aquifer is being depleted by agricultural withdrawals in the central United States?

• A. Edwards Aquifer
• B. Ogallala Aquifer
• C. Great Artesian Basin
• D. Biscayne Aquifer

Answer: (B)

The central concept here is how groundwater availability changes when withdrawals exceed natural recharge. The Ogallala Aquifer is a vast, shallow underground reservoir that underpins much of the central United States and has long provided water for irrigation. It formed from sediments laid down millions of years ago, and its water is stored in porous layers that can move slowly. In areas of the plains, irrigation for crops has pumped large volumes of water for many years. Because rainfall and natural recharge replenish the aquifer much more slowly than water is taken out, the water table has steadily declined in many spots. This sustained imbalance leads to long-term depletion of the aquifer, making it a prime example of how intensive agricultural use can outpace natural recharge.

The other options are in different regions or contexts. The Edwards Aquifer is in Texas and mainly supplies municipal water; the Biscayne Aquifer is in Florida; the Great Artesian Basin is in Australia. Their depletion dynamics and regional uses don’t match the central U.S. irrigation situation described here.