GLOSSARY OF SELECTED HYDROGEOLOGICAL TERMS*

* Definitions of common hydrogeological terms are provided for the general information of readers. For more technical definitions, consult standard hydrogeologic references.

Aquifer
From the Latin for "water carrier", a geological formation (typically porous material, such as sand or gravel, or fractured rock) that stores and is capable of transmitting water in sufficient quantities to serve as a source of water supply.

Capture Zone
The area surrounding a well that will supply groundwater to that well when pumped at a specified rate for a specified period of time.

Contaminant
An undesirable chemical or biological substance that is not normally present in groundwater, or a naturally occurring substance present in unusually high concentrations. Common contaminants include bacteria and viruses, petroleum products, chlorinated substances, pesticides, nitrates and salt.

Hydraulic Conductivity
A measure of the ability of groundwater to flow through (the subsurface environment) or (a soil or rock formation).

Groundwater
Water located below the water table that fills the pore spaces between sand, gravel, and fractures in rock, etc., that may supply water to wells or springs.

Hydrogeology
The science dealing with the physical, chemical and biological properties of groundwater.

Porosity
The open spaces or voids that occur between mineral grains or in fractures of bedrock.

Recharge Area
Area of land where surface water infiltrates down to an aquifer.

Surface Water
Includes water bodies (lakes, wetlands, ponds, etc.), water courses (rivers and streams), infiltration trenches and temporary ponds.

Time of Travel
The length of time it takes groundwater to travel a specified horizontal distance.

Wellfield
An area containing more than one pumping well that provides water to a public water supply system or single owner (i.e., Municipality).

Wellhead Protection Area
The area surrounding a well through which contaminants are reasonably likely to move toward and eventually reach the water well.