Withdrawing water for agriculture is a contentious issue. Some states particularly in the west have regulations regarding withdrawing water from wells for a region. Excessive use can deplete an aquifer or lower the water table.
NPR article of overuse of groundwater by Saudi Arabian farm in Arizona
Although approximately 70 percent of the Earth is covered with water, only about 3 percent is freshwater. All of my percentages are rounded off. Precise percentages can be found in the following two sources.
Wikipedia breakdown of world's water
USGS water resource
Of the three percent freshwater, about 1.5 percent is groundwater and 1.5 percent is glacial ice and snow. About 1/10 of a percent is the world's lakes, rivers, streams, swamps, humidity. Water is a finite resource.
Some ground water is salt water. Excessive removal of freshwater along the coastline produce an encroachment of salt water into freshwater sources.
Excessive irrigation for farming causes some land to become so salty that it cannot support farming and most plant life. Minerals are dissolved in water. Repeated watering causes a buildup of minerals. Water leaves by run-off, plant use or evaporation. The minerals are left behind.