Groundwater and Aquifers

Yes. The main body of subsurface water is found in the saturated zone of aquifers. Aquifers can be only a few feet below the surface or more than a thousand feet deep.
Groundwater is water that flows or seeps downward and saturates soil or rock, supplying springs and wells.
Groundwater, which is in aquifers below the surface of the Earth, is one of the Nation's most important natural resources.
Water being drawn from a well was once precipitation that fell onto Earth's surface. It seeped into the ground and, over time, occupied the porous space in some subsurface material.
USGS protocols for the collection of groundwater and surface-water samples have been published in the report National Field Manual for the Collection of Water-Quality Data. The National Fie
Volatile organic compounds (VOCs), which are widely used in the manufacture of many products including refrigerants, plastics, adhesives, paints, and petroleum products, have been detected in about one-third of the wells sampled by the National Water-Q
This Ground Water Atlas of the United States is a series of USGS print publications that describe the location, the extent, and the geologic and hydrologic characteristics of the important aquifers
The depth to the water table can change (rise or fall) depending on the time of year.
No. In groundwater work the USGS puts a lot of effort in measuring the water levels in observation wells.
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.