wastewater: Water that has been used. Effluent. Might contain unhealthy waste or unwanted substances, pollutants, or other contaminants.

wastewater treatment: See treat and treated.

water analysis: A chemical analysis of a water solution in which specific ions and their concentrations are determined and recorded. The character of the water solution then can be described in terms of the individual ion concentrations and the total dissolved solids, in units of ppm or mg/liter. A complete analysis will include measurement of pH, hardness, and bacteriological testing. For limits of these criteria recommended for good quality domestic water, suggested by U.S. Environmental Protection Agency (EPA), consult EPA 822-R-94-001, May 1994 or CSU. See also biochemical oxygen demand and stiff diagram.

water and sanitation districts: A special taxing district formed by the residents of the district for the combined purpose of providing potable water and sanitary wastewater services. CSU.

water balance: A mathematical construction that shows the amount of water leaving and entering a given watershed or aquifer. GWAC.

water block: For aquifers only. It pertains to the blockage in the pores of an aquifer, related to the disturbance of the equilibrium existing in the pores, by the introduction of mud filtrate or other water injected into the aquifer. This kind of blocking can be related to swelling of clays or other disturbance to clay particles and crystals. This is not the complete usage of the expression as it is used in oil or gas wells.

water commissioner: State water officials, appointed by the state engineer and working under the direction of the division engineers, who perform the dayto- day administration of surface and ground water in each water district. CSU.

water conservation: See conservation and xeriscape.

water court: A special division of a District Court with a District Judge designated as and called the Water Judge to deal with certain specific water matters principally having to do with adjudication and change of point of diversion. There are seven water courts in Colorado. CSU.

water cycle: See hydrologic cycle.

water drive: See under recovery and drainage.

water districts: Eighty geographical divisions of the state that originally were used for the granting of water rights. The districts are now largely used for administrative purposes. CSU.

water divisions: The seven geographical areas of the State of Colorado corresponding to the major natural surface water drainages. CSU.

water flux: A volume of water per unit area per time. GWAC.

water level, water level depth: (1) In an inactive water well, the depth from the ground surface to the surface of the static column of water inside the cased or uncased well bore when the pressure of the water column or hydrostatic head counterbalances the formation-water pressure or pore pressure at the drilled face of the aquifer.

(2) In an active water well, the depth from the ground surface to the surface of the column of water inside the cased well bore under dynamic or producing conditions. During production the well pump will reduce the height of the water column in the well, increasing drawdown, and thus decreasing back pressure opposing the flow of water into the well bore. See drawdown.

water loss: (1)Pertains to the quality of drilling mud. It is a measure of mud filtrate passing through mud cake over a specific length of time.

(2) Generic. Can be evaporation or percolation. water pressure: Relative to aquifers. Pore pressure. Formation pressure. Usually hydraulic, sometimes hydrostatic.

water quality standards: A plan for water-quality management consisting of four major elements:

(1) The uses to be made of water (recreation, household, fish and wildlife propagation, industrial and agricultural) .

(2) Criteria to protect the water to keep it suitable for use.

(3) Implementation plans (for necessary industrial- municipal waste treatment improvements).

(4) Enforcement plans and anti-degradation statement to protect and maintain desired high quality standards.

water right: A right to use, in accordance with its priority, a certain amount of the waters of the State by reason of the appropriation of the same CRS 37-92-103). Douglas Co.

watershed: The region draining into a river, river system or body of water; the total land area, regardless of size, above a given point on a waterway that contributes runoff water to the flow at that point; all the land that serves as a drainage for a specific stream or river. CSU.

water storage: The places where water can be stored and recovered. They can be on the ground surface or above ground in lakes, ponds, impoundments, reservoirs, tanks; or below ground in aquifers. See injection of potable water for storage purposes.

water table: The shallowest air-water interface of water-saturated earth, gravel, sand, or porous rock where the pressure at the interface is at atmospheric pressure. Might have seasonal variations. Also see perched water table.

water transfer: The legal change in a water right reflecting some combination of a conveyance of ownership of diversion, place of use, and/or type of use to another. GWAC.

water well: For the purpose of producing water. A well is normally drilled or dug into a water-bearing earthen material and then equipped with a means for power, a casing, tubing, pump and motor to produce the water. A water well consists of the entirety of all facilities, fixtures, fittings and instruments, above ground and below ground, necessary to produce ground water.

weathered, weathering: Exposure, over a period of thousands if not millions of years, to wind, rain, freezing, leaching, sun, erosion and all other natural attacks often results in degradation of the original material. The characteristics and properties of an outcrop, or near surface rock, might have characteristics and properties quite different from the buried and protected rock. All weathering of the exposed rock or outcrop increases those factors that increase the permeability of surface samples.

weir: A vertical structure in an open channel with a calibrated opening that measures water’s rate of flow. See flume. GWAC.

well: Pertaining to water, see water well.

wellhead: The fixture or equipment at the surface of a well, connected to the casing, that allows access to the well bore and downhole equipment.

Wellhead Protection Program: An amendment to the federal Safe Drinking Water Act in 1986. Initiated to minimize the potential for contamination of public ground water supplies. CSU.

well log: A generic term for the geophysical or petrophysical records that are recorded at the surface from measurements made by scientific instruments run in the borehole. A permanent record made from the measurements taken by downhole instruments as the instruments are drawn through and past the well bore environment by a winch-drawn electrical cable. Well logs are used to identify and correlate underground formations, beds, and strata; identify the mineralogy of the rocks and fluids they contain, and to determine their physical properties and characteristics.

The first electrical, downhole, well log was run by Henri G. Doll on Sept. 5, 1927 in the Pechelbronne oil field in France for Societe de Prospection Electrique, a company newly formed by brothers Conrad and Marcel Schlumberger. Electrical measurements were taken by hand at 1 meter intervals in the 500 meter drilled hole. The method first was called Electrical Coring, later to be called Electrical Survey.

(1) Any of a number of different measurements taken by downhole instruments in the open, uncased borehole for the purpose of making records of different conditions, characteristics and properties of earthen formations, beds, and strata and the fluids they contain.

(2) Any of a number of different measurements made by downhole instruments in the cased borehole environment through plastic or steel casing, primarily for the purpose of determining the quality of the completion of the well and/or evaluating the performance of the well.

(3) Logs made by collecting information at the surface; for example, analysis of cuttings brought to the surface by drilling mud.

well logging: A generic term related to the specific discipline pertaining to the recording of geophysical or petrophysical well logs and the analysis and interpretation thereof.

well permit: The granting of permission by the State Engineer allowing the digging of a hole in search of ground water to apply to a beneficial use. A written permit obtained by the state stating permission to dig a hole to find ground water. GWAC.

well screen: This term is used in water-well language to refer to the slots or perforations that are placed in the casing at the depth intervals of the aquifer or aquifers to be produced.

well-to-well interference: See equity determination, also see deplete and depleted (2).

well yield: The pumping rate that can be supplied by a well without drawing the water level in the well below the pump intake. See yield. GWAC.

wetland: A lowland area that can be or is regularly wet or flooded, such as a marsh or swamp, or lowland drainage area.

wettability: The ability of a solid to be wetted by a contacting liquid. A function of the intermolecular adhesive forces between a liquid and solid and the intermolecular cohesive forces that tend to draw the like molecules of the liquid together. The degree of wettability of a solid by a specific liquid is determined from a droplet of the liquid on the solid by measuring the contact angle formed between a tangent on the droplet at the liquidsolid contact and the plane of the solid surface. The greater the angle, as if the liquid were spreading over the solid surface, the greater is the wettability of that solid for that liquid. Wettability relative to a specific liquid can be increased by the introduction of a reactive agent that reduces the surface tension of the specific liquid.

whipstock: A long, steel, cased wedge-like device used during the drilling process to deflect the drill bit in a predetermined direction. Used in directional drilling and slant holes.

withdrawal level: The withdrawal level is usually thought of as the level from which water is produced. Must be specific: (1) Commonly thought to be the vertical depth where water emerges from the face of an aquifer.

(2) Inside the casing, the depth where water moves from outside the casing to the inside. In this case, depth of slots or perforations.

(3) Inside the casing, the depth of the ports of the water pump.

withdrawal, withdrawal process: It is commonly thought that water is drawn or withdrawn from an aquifer by the well pump. This is not wrong, but it is not technically accurate. Technically, the water from an aquifer is not withdrawn from the formation, it is withdrawn from the inside of the casing in the well bore. (Side note. The water-well pump cannot draw water to the well bore by suction. A vacuum, even if it could be created, cannot drive water to the well bore because a vacuum is neither a source of energy nor a form of force. See suction.) Water in the aquifer is driven into the well bore and the casing by hydraulic pressure, wherein the water then can be lifted to the ground surface by a pump where it is further withdrawn from the well. For every formation and every formation pressure, there is a specific hydraulic pressure gradient that is required for water to be driven toward and into the well bore. This gradient is influenced by both the hydrostatic head inside the water-well casing (through drawdown), and the formation pressure. Without a driving mechanism, and without the driving force of sufficient hydraulic pressure, there cannot be sufficient pressure gradient toward the well bore, and water cannot be produced, but simply will remain in place. For a better understanding, see aquifer, drainage, drive mechanism, hydrostatic load, hydraulic pressure, pressure gradient, pumping process.

work over: Related to remedial operations on or in a well to correct mechanical problems, perform squeeze cementing operations, set plugs, perform acid treatments, etc.

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