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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

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April 2006

Groundwater glossary

Aquifer: A rock or soil layer capable of storing, transmitting and yielding water to wells.

Baseflow: That part of stream discharge from groundwater seeping into the stream.


Consumer Confidence Report: A report, required under the amendments to the Safe Drinking Water Act, which lists contaminants found in community public well water systems, water treatment methods, devices used and potential health effects.

Discharge area: An area in which groundwater reaches the surface. Examples are springs, seeps, lakes or rivers, or by evaporation and transpiration.

Dolomite: Calcium magnesium carbonate, a common rock-forming mineral. Many rocks in Wisconsin referred to as limestone are actually dolomite.

Evaporation: The process by which water is changed from a liquid into vapor.

Geology: The science dealing with the origin, history, materials and structure of the earth, together with the forces and processes operating to produce change within and on the earth.

Glacial drift: Sediment transported or deposited by glaciers or the water melting from a glacier.

Gross alpha activity: Decay of radionuclides in natural deposits. Can be either radium or uranium.

Groundwater: Water beneath the surface of the ground in a saturated zone.

Hydrogeology: The study of groundwater and its relationship to the geologic environment.

Hydrologic cycle: The complete cycle through which water passes from the atmosphere to the earth and back to the atmosphere.

Hydrology: The science encompassing the behavior of water as it occurs in the atmosphere, on the land surface and underground.

Impermeable: Having a texture that does not permit water to move through quickly.

Infiltration: The movement of water into and through a soil.

Leachate: A liquid formed by water percolating through soluble waste material. Leachate from a landfill has a high content of organic substances and dissolved minerals.

Limestone: A sedimentary rock consisting chiefly of the mineral calcite (calcium carbonate)

Municipal well: A well, owned and operated by a municipality, serving more than 25 people for at least 60 days of the year.

Nutrients: Compounds of nitrogen, phosphorus and potassium that promote plant growth.

Onsite sewage system: Used to treat household sewage and wastewater by allowing the solids to decompose and settle in a tank, then letting the liquid be absorbed by the soil in a drainage field.

Permeability: The capacity of rock or soil to transmit a fluid, usually water.

Pesticides: A general term for insecticides, herbicides and fungicides.

Private well: A well serving one home, maintained by the owner.

Radionuclides: Any manmade or natural element that emits radiation in the form of alpha or beta particles or as gamma rays.

Recharge area: An area in which water infiltrates and moves downward into the saturated zone of an aquifer.

Runoff: Precipitation not absorbed by the soil.

Saturated zone: The part of a water-bearing layer of rock or soil in which all spaces, large or small, are filled with water.

Sludge: Sediment remaining after wastewater has been treated.

Spring: A flow or natural discharge of groundwater at the surface.

Transpiration: The process by which plants give off water vapor through their leaves.

Volatile Organic Compounds: A group of common industrial and household chemicals that evaporate or volatilize when exposed to air. Includes gasoline and solvents.

Water table: The level below which the soil or rock is saturated with water, sometimes referred to as the upper surface of the saturated zone.

Watershed: The land area from which surface runoff drains into a stream system.

Well: A vertical excavation that taps an underground liquid-bearing rock formation. In Wisconsin, wells are drilled to obtain water, to monitor the quality of groundwater or to determine the depth of the water table.

Wisconsin Unique Well Number: A number assigned to individual wells, which allows state agencies and the public to track groundwater quality through time. New wells drilled since January 1, 1988 are assigned unique well numbers.