Major North American Aquifers
Complete directory of the most important aquifers in North America. Coverage areas, depth ranges, rock types, depletion risks, and links to states that overlie each aquifer.
Basin and Range Aquifer System
The Basin and Range aquifer system consists of hundreds of individual basin-fill aquifers in the intermountain west. Each basin contains alluvial sediments eroded from adjacent mountains.
Ogallala (High Plains) Aquifer
The Ogallala Aquifer underlies 450,000 square kilometers of the Great Plains and is the largest aquifer in North America. It supplies roughly 30% of US irrigation groundwater but has been declining rapidly in its southern and western reaches since the 1950s.
Cambrian-Ordovician Aquifer System
The Cambrian-Ordovician system is a major confined aquifer spanning the upper Midwest. The St. Peter Sandstone and Jordan Sandstone are among the most productive water-bearing units.
Madison Limestone Aquifer
The Madison Limestone Aquifer is a deep, extensive carbonate aquifer underlying much of the northern Rocky Mountain region. It produces thermal water in many areas and supports several major springs.
Floridan Aquifer System
The Floridan Aquifer is one of the most productive aquifers in the world, supplying drinking water to nearly 10 million people and feeding the largest concentration of freshwater springs on Earth. Its karst limestone geology creates both extraordinary productivity and vulnerability to contamination.
Mississippi Embayment Aquifer
The Mississippi River Valley Alluvial Aquifer is the third-most heavily pumped aquifer in the US, supplying irrigation for millions of acres of cotton, rice, and soybeans in the Delta region.
Columbia Plateau Basalt Aquifer
The Columbia Plateau Basalt Aquifer consists of stacked basalt lava flows covering parts of Washington, Oregon, and Idaho. Water flows through rubble zones between flows, making it highly productive but heterogeneous.
Central Valley Aquifer
The Central Valley Aquifer system underlies California's most productive agricultural region. Decades of groundwater pumping have caused dramatic land subsidence — in some areas, the ground surface has dropped over 30 feet.
Snake River Plain Aquifer
The Eastern Snake River Plain Aquifer is one of the most productive aquifers in the United States, with water flowing through highly permeable basalt layers. It supplies most of southern Idaho's irrigation and feeds the spectacular Thousand Springs in the Snake River Canyon.
Edwards Aquifer
The Edwards Aquifer is a highly productive karst aquifer in south-central Texas that serves as the sole source of drinking water for San Antonio and surrounding communities. Its rapid recharge and discharge make it both prolific and vulnerable.