The Snake River Aquifer is a large reservoir of

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available fresh water in the world is groundwater. A unit ...

underlying the Snake River Plain in the southern part of the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its so ...

Idaho Idaho ( ) is a landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

. Most of the water in the aquifer comes from irrigation recharge. Measuring about from east to west, it is an important water source for agricultural irrigation in the Plain. The Snake River Aquifer is commonly defined as two separate parts, separated by

Salmon Falls Creek Salmon Falls Creek is a tributary of the Snake River, flowing from northern Nevada into Idaho in the United States. Formed in high mountains at the northern edge of the Great Basin, Salmon Falls Creek flows northwards ,U.S. Geological Survey. Na ...

: the Eastern Snake River Plain Aquifer and Western Snake River Plain Aquifer.

Eastern Snake River Plain Aquifer

The Eastern Snake River Plain Aquifer north of the Snake River is a remarkable aquifer of great resource and economic significance. It is not a single homogeneous geologic formation. Rather it consists of a volcanic pile of the

Quaternary The Quaternary ( ) is the current and most recent of the three periods of the Cenozoic Era in the geologic time scale of the International Commission on Stratigraphy (ICS), as well as the current and most recent of the twelve periods of the ...

Snake River Group

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

s. In eastern Idaho, these basalts may be about thick. The individual flows are thick with the upper consisting of a very permeable rubble zone. Interbedded

alluvial Alluvium (, ) is loose clay, silt, sand, or gravel that has been deposited by running water in a stream bed, on a floodplain, in an alluvial fan or beach, or in similar settings. Alluvium is also sometimes called alluvial deposit. Alluvium is ...

sediments are also found between many of the flows. In the eastern Snake River Plain, the Snake River lies near the southern edge of the plain, about southeast of the ranges of central Idaho. The rivers in the ranges north of the plain all disappear into the surface of the Snake River Plain near the mountain front. The Little Lost River is a typical example. For about 100 miles downstream from Milner Dam in the vicinity of Twin Falls an estimated total volume of approximately of water enter the Snake River from gigantic springs on the north side of the canyon. This is the well-known Thousand Springs area. Groundwater flows to the southwest through the Snake River Plains aquifer which is consistent with the overall tilt to the southwest of the basalt

strata In geology and related fields, a stratum (: strata) is a layer of Rock (geology), rock or sediment characterized by certain Lithology, lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by v ...

. The channel of the Snake River cuts through the aquifer. Consequently, the gravity and weight of the water in the basalt layers north of the river drives the huge springs.

References

Aquifers in the United States Snake River Bodies of water of Idaho {{Idaho-geo-stub