Which consequence is associated with over-extracting groundwater from an aquifer?

• A. Lower water tables and potential subsidence and water quality issues
• B. Increased surface water flow
• C. No effect on water quality
• D. Over-extraction has no issues

Answer: (D)

Over-extracting groundwater lowers the water table because you’re removing more water than the aquifer can replenish. This creates a cone of depression around wells and, with long-term pumping in some aquifers, can cause the sediments to compact and the ground to subside. Lower water levels can also worsen water quality by concentrating minerals and contaminants and by allowing saline intrusion in coastal areas. Additionally, less groundwater discharge to streams reduces baseflow, affecting surface water. So, the combination of falling water tables, potential subsidence, and water quality changes are the expected consequences of over-extraction.