USGS Frequently Asked Questions

Answer:

Water levels in wells are constantly changing both in the short term and over the long term. Some wells even have a seasonal change. In the short term, water levels can be lowered just by pumping water out of the well for use. Also, a well may be pumped so much as to cause the water level in nearby wells to be lowered, too. It all depends on how fast the aquifer that the well uses is resaturated with water from the surface or from the area surrounding it (recharge). In some places people have withdrawn water faster than water replenishes the aquifer, and the wells have stopped producing water.

Sometimes this is a long-term problem occurring over a very large area. If it takes a long time to replenish the aquifer, maybe because the aquifer is composed of rock that only allows water to move through it very slowly, a field of wells may stop producing. Users will have to wait until the aquifer becomes more saturated again before turning the pumps back on. Also, an aquifer can only contain water if there is water coming into it, usually from rainwater seeping down from the surface. In a severe drought water levels in wells can significantly decline.