A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Cable Tool Drilling (Jumper rig)
Drilling by cable tool (percussion drilling) is achieved by the breaking and crushing action of heavy drilling tools suspended on a cable which are repeatedly lifted and dropped. See also bailer.

Calcite
Calcium carbonate (CaCO3) is the principal mineral in limestone.

Caliche
A crust-like accumulation of impure calcium carbonate that may occur as layers within soils and sediments of arid areas. It is formed by calcium-rich water near to the ground surface which, when evaporated, leaves behind an accumulation of calcium carbonate.

Capillary Rise
The natural occurrence of water in contact with, but rising above the water table. Caused by surface tension forces in the pore spaces of the rock, soil or vegetation layers that are not fully saturated. In permeable formations with fine pore spaces, capillary rise of water can be as much as 6 feet above the water table. This is known as the "capillary-fringe" of an aquifer.

Carbonates
Rocks such as limestone and dolomite that are comprised principally of carbonate minerals.

Casing
A cylindrical device (steel or plastic) that is installed in a well to maintain the well opening and to provide a seal. In most states casing is required for at least the first 20 or 40 feet of water wells. Well drillers typically install well casing in 20 foot lengths.

Center-Pivot Irrigation
An Irrigation system that applies water from nozzles on a fixed boom that moves in a circular fashion from a central point.

Channel Flow
Surface water flow within the boundaries of a defined natural channel, e.g., streams and rivers.

Chlorine
An effective oxidizing agent used in water treatment. Chlorine has been used for almost 100 years by water utilities to kill microorganisms.

Clastic Rock
Any rock composed of "pieces" (clasts) of pre existing rocks. Most sedimentary rocks are clastic.

Clay
Fine grained sediment derived from the weathering of rock minerals. Clay can store water but not transmit water. See also bentonite.

Coefficient of Storage
The volume of water that an aquifer adds or loses from storage per unit area/per unit change of head.

Coliform
A broad group of naturally occurring bacteria species found in soils and rocks. Coliform bacteria are more prevalent in near-surface soils and their presence in well water in large numbers may indicate the possibility of the presence of more harmful pathogens.

Commercial Water Use
Water used for motels, hotels, restaurants, office buildings, other commercial facilities, and institutions. Water for commercial uses comes both from public-supplied sources, such as a county water department, and self-supplied sources, such as local wells.

Community Water Supply
(Definition used by the US Environmental Protection Agency for water supply systems in the US). Water supplied by a water utility, distributed through pipelines and serving at least fifteen homes or twenty five persons. See also Non-Community Water Supply.

Condensation
The process by which water vapor in the air changes to liquid water. Water drops on the outside of a cold glass of water are condensed water. Condensation is the opposite process of evaporation.

Cone of Depression
A shape in the form of an inverted cone that develops in the water table (or potentiometric surface) as a result of pumping from a well. In practice the shape of the "cone" resulting from pumping from a well is often not symmetrical.

Confined Aquifer
An aquifer, overlain by an impermeable layer, in which the water is under pressure greater than that of the atmosphere. See also artesian.

Confined Aquifer
Soil or rock below the land surface that is saturated with water. There are layers of impermeable material both above and below it and it is under pressure so that when the aquifer is penetrated by a well, the water will rise above the top of the aquifer.

Conglomerate
Sedimentary rock comprised of non-sorted cemented particles including gravel size and above. See also grain size.

Conjunctive Use
A management strategy for using both ground water and surface water to maximize resources. For example, artificial recharge of aquifers with surplus surface water for later use when surface sources are scarce.

Consumptive Use
That part of water withdrawn that is evaporated, transpired by plants, incorporated into products or crops, consumed by humans or livestock, or otherwise removed from the immediate hydrologic system. Also referred to as water consumed. Homes that have a well and an on-site septic system will typically return over 70% of water to the aquifer. Actual consumptive use from the well is therefore 30%.

Contamination
A reduction in water quality resulting from land use activities or accidents that add toxic or undesirable chemicals, organisms or particulate matter to the hydrologic system.

Conveyance Loss
Water that is lost in transit from a pipe, canal, or ditch by leakage or evaporation. Generally, the water is not available for further use; however, leakage from an irrigation ditch, for example, may percolate to a ground water source and be available for further use. Some water utilities in major urban areas can lose up to 20% of water because of leaking pipes.

Creek
A natural stream of water, usually small in size. Many creeks are intermittent and flow only after rain. There are regional variations in the way that people describe natural features. In some areas of the US the word creek describes small tidal streams in estuaries and mudflats.

Cryptosporidium
A microscopic aquatic organism typically present in surface water, that if ingested, may cause gastro-intestinal problems in humans.

Cubic feet per second (cfs)
A measure of the rate of the flow, as a unit volume, in streams, rivers, canals etc. It is equal to a volume of water one foot high and one foot wide flowing a distance of one foot in one second. One cubic foot is equal to 7.48 gallons. As an example, a child's paddling pool, 4 foot x 4 foot x 1 foot deep (16 cubic feet), would be filled in 8 seconds by water flowing at a rate of 2cfs.