Key Terms


An aquifer is an underground layer of sand, gravel or rock through which water can pass and is stored. Aquifers supply the water for wells and springs.

In the Black Hills, the Madison and Minnelusa area are most widely used.

Artesian Aquifer

An aquifer that contains water that would rise above the top of the aquifer in a penetrating well; also confined aquifer.

Base Flow

That part of streamflow that is sustained primarily by ground-water discharge. It is not attributable to direct direct runoff from precipitation or melting snow.

Lake Pactola

Hydrologic Cycle

The Hydrologic Cycle, also known as the Water Cycle, describes the continuous movement of water on, above and below the surface of the Earth.


Factors that deal with geologic influences on water.

Nonpoint Source Pollution(NSP)

NSP is pollution affecting a water body from widespread sources, such as runoff from an agricultural area draining into a river, or wind-borne debris blowing out to sea; whereas, Point Source Pollution can be described as pollution to a body of water at a single location, such as discharges from a factory.

NPS may be derived from many different sources with no specific solution to rectify the problem, making it difficult to regulate. It is the primary cause of water pollution in the United States, with polluted runoff from agriculture the primary source.

Water Table

The top of the water surface in the saturated zone of an unconfined aquifer.

Water Year

The 12-month period, October 1 through September 30, that is designated by the calendar year in which it ends.

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