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Calcareous — Formed of calcium carbonate or magnesium carbonate by biological deposition or inorganic precipitation in sufficient quantities to effervesce carbon dioxide visibly when treated with cold 0.1 normal hydrochloric acid. Calcareous sands are usually formed of a mixture of fragments of mollusk shell, echinoderm spines and skeletal material, coral, foraminifera, and algal platelets.


Caliche —
(1) A soil layer near the surface, more or less cemented by secondary carbonates of calcium or magnesium precipitated from the soil solution. It may occur as a soft, thin soil horizon, as a hard, thick bed just beneath the Solum, or as a surface layer exposed by erosion.
(2) Alluvium cemented with sodium nitrate, chloride, and/or other soluble salts in the nitrate deposits of Chile and Peru. Also referred to as Hardpan.

California Doctrine — A system of allocating water, first announced in California, which combines Riparian Rights and Appropriative Rights. A number of states have applied this doctrine at one time or another. However, most states have essentially abandoned the doctrine in favor of the Appropriation Doctrine, and it is primarily of historical significance. Also see Alpine Decree [California and Nevada].

California Environmental Quality Act (CEQA) — The California equivalent of the federal National Environmental Policy Act (NEPA).

California Species of Special Concern — Species which are not federal or state-listed as endangered, threatened, or rare, but are declining or are so few in number in California that extirpation is a possibility.

Candidate Species — Plant or animal species designated by the Department of the Interior, U.S. Fish and Wildlife Service (USFWS) as candidates for potential future listing as an Endangered Species or Threatened Species pursuant to the Endangered Species Act (ESA) of 1973; plant or animal species that are candidates for designation as endangered (in danger of becoming extinct) or threatened (likely to become endangered).

Canopy —
(1) The overhanging cover formed by leaves, needles, and branches of vegetation.
(2) The more or less continuous cover of branches and foliage formed collectively by the crowns of adjacent trends and shrubs.

Canopy Resistance — The resistance to transport of water and vapor away from the soil and canopy.

Capacitive Deionization (CDI) — A relatively simple and straight forward electrochemical reaction process made unique and highly efficient through the development of a highly-porous material called carbon aerogel that absorbs huge volumes of ions. A single cube of carbon aerogel, one inch on a side, has an effective surface area of more than 20 million square inches. This unusually high surface area makes it possible to adsorb large numbers of ions.
Water containing salt, heavy metals, or even radioactive isotopes is pumped through a series of electrochemical cells made from the aerogel, a material sometimes called “frozen smoke.” Effluent water from the series of stacked cells is subsequently purified. The trapped ions can be released into a relatively small stream of “rinse” water typically comprising less than one percent of the total volume of produce water.

Carbon-Chloroform Extract (CCE) — A measurement of the organic content of a water. It consists of adsorbing the organic matter onto activated carbon, then extracting it with chloroform.

Carbonate Buffer System — The most important buffer system in natural surface waters and wastewater treatment, consisting of a carbon dioxide, water, carbonic acid, Bicarbonate, and Carbonate ion equilibrium that resists changes in the water’s pH. For example, if acid materials (hydrogen ions) are added to this buffer solution, the equilibrium is shifted and carbonate ions combine with the hydrogen ions to form bicarbonate. Subsequently, the bicarbonate then combines with hydrogen ions to form carbonic acid, which can dissociate into carbon dioxide and
water. Thus the system pH is unaltered even though acid was introduced.

Carbonate Hardness — Water hardness caused by the presence of Carbonate and Bicarbonate of calcium and magnesium.

Catabolism — The biological breakdown of materials into their simpler components, i.e., decomposition. Performed by decomposer organisms, mainly bacteria and fungi.

Catadromous — Used to describe fish that live in fresh water but migrate to marine waters to breed.

Central Valley Project (CVP) [California] — A multipurpose water project developed mainly by the U.S. Bureau of Reclamation (USBR), extending from the Cascade Range on the north to the semiarid but fertile plains of California’s Kern River on the south. The state and federal portions of the Central Valley Project (CVP) encompass twenty dams and reservoirs, pumping facilities, 500 miles of canals, and aqueducts providing protection from saltwater intrusion into the Bay-Delta region (also referred to as the Sacramento-San Joaquin Delta), irrigation water for San Joaquin Valley farms, and municipal and industrial water for some of California’s most populated
urban areas. Each year some seven million acre-feet of water are transported through the system and delivered primarily to Central Valley farmers. The construction of the CVP was approved by California voters in a 1933 referendum of the California Central Valley Project Act. Due to the effects of the Great Depression, the state was unable to construct the project at that time. Subsequently, portions of the CVP were authorized and constructed by the federal government. Other portions were later constructed by California after the Depression as part of the
State Water Project (SWP), as authorized under the 1960 Burns-Porter Act. Principal facilities of the SWP include Oroville Dam, Delta Facilities, the California Aqueduct, and North and South Bay Aqueducts. Principle facilities of the federal CVP include Shasta, Trinity, Folsom, Friant, Clair Engle, Whiskeytown, and New Melones dams, Delta facilities, and the Delta Mendota Canal. Joint CVP/SWP facilities include San Luis Reservoir and Canal and various Delta facilities.

Chalybeate — Tasting like iron, as water from a mineral spring.

Channel Density — The ratio of the length of stream channels in a given basin to the area of the basin, expressed in feet per acre (meters per hectare).

Channel Stabilization — Erosion prevention and stabilization of velocity distribution in a channel using jetties, drops, revetments, vegetation, and other measures.

Channelization —
(1) The artificial enlargement or realignment of a stream channel.
(2) Straightening a stream or river to allow water to travel through the area more quickly.
(3) The process of changing an straightening the natural path of a waterway. Channelization is often used as a means of flood control, but its negative effects often outweigh its advantages. For example, channelization often damages wetlands associated with rivers and streams.

Chaos Theory — A modern development in mathematics and science that provides a framework for understanding irregular or erratic fluctuations in nature. Chaotic systems are found in many fields of science and engineering. Evidence of chaos occurs in models and experiments describing convection and mixing in fluids, in wave motion, in oscillating chemical reactions, and in electrical currents in semiconductors. It is also found in the dynamics of animal populations and attempts are being made to apply chaotic dynamics in the social sciences, such as the study
of business cycles. A chaotic system is defined as one that shows “sensitivity to initial conditions.” That is, any uncertainty in the initial state of the given system, no matter how small, will lead to rapidly growing errors in any effort to predict its future behavior. This “sensitivity to initial conditions” will make any long-term prediction of such phenomenon virtually impossible in reality. In other words, the system is chaotic and as such its behavior can
be predicted only if the initial conditions are known to an infinite degree of accuracy, which is impossible. The possibility of chaos in a natural, or deterministic, system was first envisaged by the French mathematician Henri Poincare in the late 19th century. More recently, predictions have been made that the transition to chaotic turbulence in a moving fluid would take place at a well-defined critical value of the fluid’s velocity (or some other important factor controlling the fluid’s behavior). The term chaotic dynamics refers only to the evolution of a system in time. Chaotic systems, however, also often display spatial disorder — for example, in complicated fluid
flows.

Check Dam —
(1) A structure placed bank to bank downhill from a headcut on a hillslope to help revegetate a gully.
(2) A small dam constructed in a gully or other small watercourse to decrease the streamflow velocity, minimize
channel erosion, promote deposition of sediment, and to divert water from a channel.

Check Gate — A gate located at a check structure used to control flow.

Check Irrigation — A method of irrigation in which an area is practically or entirely surrounded by earth ridges.

Check Structure — A device or structure placed in a canal such that water must pass through, over or under it. The check structure opening or position is typically a function of the flow rate, and is adjusted to maintain a certain flow rate or water level. Check structures are necessary to dam the water up during low flows so that all turnouts upstream can receive water. Also referred to as a Cross Regulator or Gate.

Chemigation — Application of pesticides or fertilizers to farmlands through irrigation systems.

Chresard — Water present in the soil and available for plant absorption.

Cienega — A Southwestern United States, non-forested wetland. Cienegas are dominated by Graminoids and may be seasonally dry.

Cirque — A smallish, rounded depression with steeply sloping sides carved into the rock at the top of a ridge where a glacier has its head. After the period of glaciation ends, the cirque may contain a small remnant of the former glacier, or it may fill with water and become a lake. The term Tarn is also used to describe lakes that have formed in cirques.

Cistern — An artificial reservoir or tank used for holding or storing water or other liquids. Typically a tank, often underground, used for storing rain water collected from a roof.

Clast (Clastic) —
(1) Pertaining to a rock or sediment composed principally of broken fragments that are derived from pre-existing rocks or minerals and that have been transported some distance from their places of origin.
(2) An individual constituent, grain, or fragment of a sediment or rock, produced by the mechanical weathering (disintegration) of a larger rock mass.

Clepsydra — An ancient device that measured time by marking the regulated flow of water through a small opening. Also referred to as a Water Clock or Water Glass.

Closed-Cycle Cooling — A process in which cooling water used in industrial processes or in the generation of electrical energy is not discharged into receiving streams, where direct discharge can have adverse effects, but is circulated through cooling towers, evaporators, ponds, or canals to allow the dissipation of the heat, and the water to be reused.

Coefficient of Transmissivity (t) — The rate at which water of the prevailing kinematic viscosity is transmitted through a unit width of the aquifer under a unit Hydraulic Gradient. It is equal to an integration of the hydraulic conductivities across the saturated part of the aquifer perpendicular to the flow paths. Also, the rate at which water is transmitted through a unit width of an aquifer under a unit hydraulic gradient. Transmissivity values are given in gallons per minute through a vertical section of an aquifer 1 foot wide and extending the full saturated height of an aquifer under a hydraulic gradient of one in the English Engineering System; in the Standard International System, transmissivity is given in cubic meters per day through a vertical section of an aquifer 1 meter wide and extending the full saturated height of an aquifer under hydraulic gradient of one. It is a function of properties of the liquid, the porous media, and the thickness of the porous media.

Cofferdam — A temporary watertight enclosure that is pumped dry to expose the bottom of a body of water so that construction, as of piers, a dam, and bridge footings, may be undertaken. Also, a watertight chamber attached to the side of a ship to facilitate repairs below the water line. A Diversion Cofferdam prevents all downstream flow by diverting the flow of a river into a pipe, channel, or tunnel. Also see Dam, Caisson and Camel.

Coldwater Fish — A fish that requires relatively cool water for survival. While the optimum temperature varies by species, most are found in water where temperatures are 20EC (68EF) or less.

Coliform (Bacteria) —
(1) A group of bacteria predominantly inhabiting the intestines of man or animals but also found in soil. While typically harmless themselves, coliform bacteria are commonly used as indicators of the possible presence of pathogenic organisms.
(2) A group of organisms (Colon bacilli) usually found in the colons of animals and humans; non-pathogenic microorganisms used in testing water to indicate the presence of pathogenic bacteria. The presence of coliform bacteria in water is an indicator of possible pollution by fecal material. Generally reported as colonies per 100 milliliters (ml) of sample.

Colloidal Suspension — Suspension in water of particles so finely divided that they will not settle under the action of gravity, but will diffuse, even in quiet water, under the random impulses of Brownian Movement. Particles typically range in size from about one micron (0.000001 millimeter) to about one millimicron; however, there is no distinct differentiation by particle size between true Suspension and colloidal suspension or between colloidal
suspension and Solution.

Colloids —
(1) Any substance with particles in such a fine state of subdivision dispersed in a medium (for example, water) that they do not settle out, but not in so fine a state of subdivision that they can be said to be truly dissolved.
(2) Quantities of extremely small particles, typically 0.0001 to 1 micron in size, and small enough to remain suspended in a fluid medium without settling to the bottom. Substances that, when apparently dissolved in water or other liquid, diffuse not at all or very slowly through a membrane and show other special properties, as lack of pronounced effect on the freezing point or vapor pressure of the solvent. Colloids represent intermediate substances between a true dissolved particle and a suspended solid, which will settle out of solution.

Colluvial Material — (Geology) Material consisting of Alluvium in part and also containing angular fragments of the original rocks. Typically found at the bottom or on the lower slopes of a hill.

Colluvium —
(1) A general term used to describe loose and incoherent deposits of rock moved downslope by gravitational force in the form of soil Creep, slides, and local wash.
(2) A general term applied to any loose, heterogeneous, and incoherent mass of soil material or rock fragments deposited chiefly by gravity-driven masswasting usually at the base of a steep slope or cliff, for example, talus, cliff debris, and avalanche material.
(3) Alluvium deposited by unconcentrated surface run-off or sheet erosion, usually at the base of a slope. Also see Colluvial Material.

Colvin Algorithm — A canal flow control structure technique that operates the gates based on the rate of deviation
of the water surface level from the setpoint.

Compensation Point — The point under water at which plant photosynthesis just equals plant respiration. The water depth defines the lower boundary, where photosynthesis takes place, of the Euphotic Zone. Also referred to as the Compensation Level.

Compliance Monitoring — (Water Quality) Collection and evaluation of data, including self-monitoring reports, and verification to show whether pollutant concentrations and loads contained in permitted discharges are in compliance with the limits and conditions specified in the permit.

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) — Also referred to as the Superfund Law, this statute, originally enacted in 1980 and substantially modified in 1986, establishes the U.S. Environmental Protection Agency’s (EPA) authority for emergency response and cleanup of hazardous substances that have been spilled, improperly disposed of, or released into the environment. The primary responsibility for response and cleanup is on the generators or disposers of the hazardous substances, with a backup federal response using a trust fund provision.

Concentration Time — The period of time required for storm runoff to flow from the most remote point of a catchment or drainage area to the outlet or point under consideration. Concentration time varies with depth of flow and channel condition.

Concordant Flows — Flows at different points in a river system that have the same Recurrence Interval, or the same frequency of occurrence. It is most often applied to flood-flows.

Conductance — A rapid method of estimating the dissolved solids content of a water supply by determining the capacity of a water sample to carry an electrical current.

Cone of Depression (COD)/Cone of Influence (COI) — A cone-like depression of the water table or other piezometric surface that has the shape of an inverted cone and is formed in the vicinity of a well by withdrawal of water. The surface area included in the cone is known as the area of influence of the well. Also referred to as the Pumping Cone and the Cone of Drawdown.

Confined Aquifer —
(1) An aquifer containing water between two relatively impermeable boundaries. The water level in a well tapping a confined aquifer stands above the top of the confined aquifer and can be higher or lower than the water table that may be present in the material above it. In some cases the water level can rise above the ground surface, yielding a flowing well.
(2) An aquifer or water-bearing subsurface stratum which is bounded above and below by formations of impermeable or relatively impermeable material; a water-bearing formation whose upper boundary is a layer which does not transmit water readily.
(3) An aquifer in which ground water is under pressure significantly greater than atmospheric and its upper limit is the bottom of a bed of distinctly lower hydraulic conductivity than that of the aquifer itself. See Artesian Aquifer.

Confined Ground Water — A body of ground water covered by material so impervious as to sever the hydraulic connection with overlying ground water except at the intake or recharge area. Confined water moves in pressure conduits due to the difference in head between intake and discharge areas of the confined water body.

Confined Water (Artesian) — Water under artesian pressure. Water that is not confined is said to be under water table conditions.

Confining Bed — A body of “impermeable” material stratigraphically adjacent to one or more aquifers. It may lie above or below the aquifer. In nature its hydraulic conductivity may actually range from nearly zero to some value distinctly lower than that of the aquifer. In some literature, the term confining bed has now supplanted the terms Aquiclude, Aquitard, and Aquifuge. Also referred to as Confining Layer.

Confining Unit — A hydrogeologic unit of relatively impermeable material, bounding one or more aquifers. This is a general term that has replaced Aquitard, Aquifuge, and Aquiclude and is synonymous with Confining Bed.

Confirmed Test — (Water Quality) The second stage in the examination of water for the presence of bacteria of fecal origin. Cultures that are positive on the first portion of the testing procedure (the Presumptive Test) are inoculated into tubes of brilliant green lactose bile broth and examined for fermentation when incubated at 35EC (95EF) for 48 hours. If fermentation is present, a third stage, the Completed Test, is performed.

Confluence —
(1) The act of flowing together; the meeting or junction of two or more streams; also, the place where these streams meet.
(2) The stream or body of water formed by the junction of two or more streams; a combined flood.

Confluent Growth — (Water Quality) A continuous bacterial growth covering all or part of the filtration area of a membrane filter in which the bacteria colonies are not discrete. In coliform testing, abundant or overflowing bacterial growth which makes accurate measurement difficult or impossible.

Conjunctive Management — The integrated management and use of two or more water resources, such as a (groundwater) aquifer and a surface water body.

Conjunctive Operation — The operation of a ground water basin in combination with a surface water storage and conveyance system. Water is stored in the groundwater basin for later use by intentionally recharging the basin during years of above-normal water supply.

Conjunctive (Water) Use —
(1) The operation of a groundwater basin in combination with a surface water storage and conveyance system. Water is stored in the groundwater basin for later use by intentionally recharging the basin during years of above-average water supply.
(2) The combined use of surface and groundwater systems and sources to optimize resource use and prevent or minimize adverse effects of using a single source; the joining together of two sources of water, such as groundwater and surface water, to serve a particular use.
(3) The integrated use and management of hydrologically connected groundwater and surface water.

Connate Water — Water that was trapped in the interstices of a sedimentary or extrusive igneous rock at the time of its deposition. It is usually highly mineralized and frequently saline.

Consent Decree — (Environmental) A legal document approved by a judge, that formalizes an agreement reached between the U.S. Environmental Protection Agency (EPA) and a Potentially Responsible Party (PRP) or parties through which the PRP will conduct all or part of a cleanup action at a Superfund Site, cease or correct actions or processes that are polluting the environment, or otherwise comply with EPA initiated regulatory enforcement actions to resolve the contamination at the Superfund site involved. The consent decree describes the actions the PRP will take and may be subject to a public comment period.

Consequent Stream — A stream following a course that is a direct consequence of the original slope of the surface on which it developed.

Conservation District — A public organization crated under state-enabling law as a special purpose district to develop and carry out a program of soil, water, and related resource conservation, use, and development within its boundaries. In the United States, such districts are usually a subdivision of state government with a local governing body and are frequently called a soil conservation district or a soil and water conservation district.

Conservation Easement — An agreement negotiated on privately owned lands to preserve open space or protect certain natural resources.

Conservation Standards — Standards for various types of soils and land uses, including criteria, techniques, and methods for the control of erosion and sediment and impacts on plant and animal species and necessary habitat resulting from land disturbing activities.

Consolidated Aquifer — An aquifer made up of consolidated rock that has undergone solidification or lithification.

Consolidated Formation — Geological formations which occur naturally and have been turned to stone. The term is sometimes used interchangeably with the word Bedrock. It includes rock such as basalt, rhyolite, sandstone, limestone and shale. Typically, these formations will stand at the edges of a bore hole without caving.

Consolidation — (Soil Mechanics) Adjustment of a soil in response to increased load; involves squeezing of water from the pores and a decrease in void ratio (pore space). Frequently the geologic term Compaction is used instead.

Consolidation Grouting (of a Dam) — The injection of grout to consolidate a layer of the foundation, resulting in greater impermeability and/or strength. Also referred to as Blanket Grouting. Also see Blanket (of a Dam).

Consolute — Of or relating to liquid substances that are capable of being mixed in all proportions.

Constant Head Orifice Turnout (Canal) — A calibrated structure containing an adjustable orifice gate and a gate downstream to control a constant head differential across the orifice gate to divert and measure water from a main irrigation canal to a distributing canal.

Constructed Wetlands —
(1) Wetlands constructed by man either as part of a Wetland Banking, Wetland Clumping (Aggregation), or Wetland Mitigation program, or to achieve some other environmental preservation or restoration program.
(2) (Water Quality) Wetlands constructed specifically for the purpose of treating waste water effluent before re-entering a stream or other body of water or being allowed to percolate into the groundwater.

Consumptive (Water) Use —
(1) A use which lessens the amount of water available for another use (e.g., water that is used for development and growth of plant tissue or consumed by humans or animals).
(2) A use of water that renders it no longer available because it has been evaporated, transpired by plants, incorporated into products or crops, consumed by people or livestock, or otherwise removed from water supplies.
(3) The portion of water withdrawn from a surface or groundwater source that is consumed for a particular use (e.g., irrigation, domestic needs, and industry), and does not return to its original source or another body of water. The terms Consumptive Use and Nonconsumptive Use are traditionally associated with water rights and water use studies, but they are not completely definitive. No typical consumptive use is 100 percent efficient; there is always some return flow associated with such use either in the form of a return to surface flows or as a ground water recharge. Nor are typically nonconsumptive uses of water entirely nonconsumptive. There are evaporation losses, for instance, associated with maintaining a reservoir at a specified elevation to support fish, recreation, or hydropower, and there are conveyance losses associated with maintaining a minimum streamflow in a river, diversion canal, or irrigation ditch.

Contributing Area — That portion of a watershed which contributes to measured runoff under normal conditions.

Controlled Volume Operation Method (Canal) — An operation in which the volume of water within a canal reach between two check structures is controlled in a rescribed manner for time variable inflows and outflows such as offpeak pumping or canal-side deliveries.

Convective Transport — The component of movement of heat or mass induced by thermal gradients in ground water.

Correlative Estimate — A discharge or stream flow estimate determined by Correlation, or comparisons to other, possibly influencing factors, e.g., rainfall, snowpack, levels of upstream lakes and reservoirs, etc. A correlative estimate represents a likely value of the discharge or flow for any particular period — commonly a month — according to a specified method of analysis and the explanatory variables chosen.

Criterion — A standard rule or test on which a judgment or decision can be based.

Cryptosporidium Parvum — A parasite often found in the intestines of livestock which contaminates water when the animal feces interact with a water source.

Cultural Eutrophication — The increasing rate at which water bodies “die” by pollution from human activities.

Cunette — A longitudinal channel constructed along the center and lowest part of a channel or through a detention or retention facility and intended to carry low flows. Also referred to as a Trickle Channel.

Cut Bank — The outside bank of a bend, often eroding opposite a point bar.