This principal aquifers map is available for download as a wall-map-sized PDF (14.4 MB), a printable PDF (1.7 MB), or available for purchase from the USGS Store.
An aquifer is a geologic formation, a group of formations, or a part of a formation that contains sufficient saturated permeable material to yield significant quantities of water to wells and springs. The areal and vertical location of major aquifers is fundamental to … [more…]