Contraction jointContraction joints are joints placed in concrete to provide for volumetric shrinkage of a monolithic unit or movement between monolithic units.
Control areaAn electric power system or combination of electric power systems to which a common automatic control scheme is applied in order to: Match, at all times…
Control jointControl joints are joints placed in concrete to provide for control of initial shrinkage stresses and cracks of monolithic units.
Control PointsHorizontal and Vertical: Small monuments securely embedded in the surface of the dam. Any movement of the monument indicates a movement in the dam itself.
Control structure (control house)Concrete portion of an outlet works, located at the downstream end of the tunnel or conduit, housing the control (regulation) gates.
Conventional tillageThe traditional method of farming in which soil is prepared for planting by completely inverting it with a moldboard plow.
Conveyance LossThe loss of water from a conduit due to leakage, seepage, evaporation, or evapo-transpiration.
Conveyance loss (distribution loss)Loss of water from a channel or pipe during conveyance, including losses due to seepage, leakage, evaporation and transpiration by plants growing in or…
Conveyance system efficiencyThe ratio of the volume of water delivered to users in proportion to the volume of water introduced into the conveyance system.
ConveyorA mechanical apparatus for carrying bulk material from place to place; for example, an endless moving belt or a chain of receptacles.
Cooperative AgreementFormal document that states the obligations of Reclamation to one or more other parties.
Cooperative electric utilityAn electric utility legally established to be owned by and operated for the benefit of those using its service.
Cooperative ObserverAn individual (or institution) who takes precipitation and temperature observations-and in some cases other observations such as river stage, soil…
Coordinated operationGenerally, the operation of two or more interconnected electrical systems to achieve greater reliability and economy.
CoordinationThe practice by which two or more interconnected electric power systems augment the reliability of bulk electric power supply by establishing planning and…
Coral ReefsLarge living structures of calcium carbonate produced primarily by coral polyps.
CorduroyA road made of logs laid crosswise on the ground or on other logs.
Core (impervious core or impervious zone)A zone of low permeability material in an embankment dam. Sometimes referred to as "central core," "inclined core," "puddle clay core," and "rolled clay…
Core drillA rotary drill, usually a diamond drill, equipped with a hollow bit and a core lifter.
Core WallA wall of substantial thickness built of impervious material, usually of concrete or asphaltic concrete, in the body of an embankment dam to prevent…
CorrelationIn investment terms, correlation is the extent to which the values of different types of investments move in tandem with one another in response to…
CorridorA strip of land through which one or more existing or potential facilities may be located.
CorrosionWear or dissolving away through chemical action as by rusting, or acids. The gradual decomposition or destruction of a material by chemical action, often…
Cost allocationProcedures used to allocate joint project costs to specific purposes in a multipurpose project.
Cost effectivenessEconomic efficiency, obtaining the best method for the least amount of money.
Cost-benefit analysisA quantitative evaluation of the costs which would be incurred versus the overall benefits to society of a proposed action.
CouleesSmall streams or dry streambeds. A deep gulch or ravine, usually dry in the summer.
CoulombA unit for the quantity of electricity transported in 1 second by a current of 1 ampere.
County Warning Forecast Area (CWFA)(CWFA)The area (aggregation of counties, or parishes and sometimes portions of counties, or parishes) served by a WFO for which weather forecast and warning…
Cover cropA crop that provides temporary protection for delicate seedlings and/or provides a canopy for seasonal soil protection and improvement between normal crop…
Coyote holesHorizontal tunnels in which explosives are packed for blasting a high rock face.
CrackTo beat a hand - typically a big hand. You hear this most often applied to pocket aces: "Third time tonight I've had pocket aces cracked."
CrazingA network pattern of fine cracks in concrete that do not penetrate much below the surface.
CreekA small stream of water which serves as the natural drainage course for a drainage basin of nominal, or small size.
Crest GageA gage used to obtain a record of flood crests at sites where recording gages are installed.
Crest Gate (Spillway Gate)A gate on the crest of a spillway to control the discharge or reservoir water level.
Crest LengthThe length of the top of a dam from left abutment to right abutment, including the length of spillway, powerhouse, navigation lock, fish pass, etc.
Crest length (length of dam)The distance, measured along the axis or centerline crest of the dam at the top level of the main body of the dam or of the roadway surface on the crest…
Crest of DamThe elevation of the uppermost surface of a dam excluding any parapet wall, railings, etc.
Crest structurePortion of spillway between the inlet channel and the chute, tunnel or conduit, which does not contain gates.
Crest WidthThe width or thickness of a dam at the level of the crest of the dam. In general, the term "thickness" is used for gravity and arch dams and "width" is…
Crest Width (Top thickness)The thickness or width of a dam at the level of the top of dam (excluding corbels or parapets).
Crib DamA gravity dam built up of boxes, cribs, crossed timbers or gabions, filled with earth or rock.
Critical DepthThe depth of flow when the Froude number equals one. The depth of flow at which the discharge is maximum for a given specific energy, or the depth at…
Critical dischargeThe maximum discharge for a given specific energy, or the discharge which will occur with minimum specific energy.
Critical FlowWhen the Froude number is equal to one, the flow is critical and surface waves remain stationary in the flow. Flow at critical depth.
Critical habitatThe specific area within the geographical area occupied by the species at the time it is listed as endangered or threatened.
Critical heightThe maximum height at which a vertical or sloped bank of soil will stand unsupported under a given set of conditions.
Critical Rainfall Probability (CRP)(CRP)The probability that the actual precipitation during a rainfall event has exceeded or will exceed the flash flood guidance value.
Critical slopeThe maximum angle with the horizontal at which a sloped bank of soil or rock of given height will stand unsupported.
Crop irrigation requirementQuantity of water, exclusive of effective precipitation, that is needed for crop production. See irrigation requirement.
Crop root zoneThe soil depth from which a mature crop extracts most of the water needed for evapotranspiration.
Crop rotationA pattern of changing the crops grown in a specific field from year to year in order to control pests and maintain soil fertility.
Crop subsidyPrice support paid by the government to farmers.
Crop water requirementCrop consumptive use plus the water required to provide the leaching requirements.
Cropping patternThe acreage distribution of different crops in any one year in a given farm area such as a county, water agency, or farm.
Cross-sectionSlice of the channel and adjacent valley made perpendicular to the assumed flow.
Cross-sectional areaArea of a stream, channel or waterway, usually measured perpendicular to the flow.
CrownThe base of the stem of cereals and forage species from which tillers or branches arise. In woody plants, the root-stem junction.
Crushed gravelGravel which has been produced by a machine.
Crushed rockRock which has been reduced in size by a machine.
CrusherA machine which reduces rocks to smaller and more uniform sizes.
CryologyThe science of the physical aspects of snow, ice, hail, and sleet and other forms of water produced by temperatures below Zero degrees Celsius.
Cubic Feet Per SecondA unit expressing rates of discharge. One cubic foot per second is equal to the discharge through a rectangular cross section, 1 foot wide by 1 foot deep…
Cubic feet per second (cfs or ft3/s)A unit of discharge for measurement of a flowing liguid equal to a flow of 1 cubic foot per second (448.8 gallons per minute (gpm), 7.
Cubic Feet per Second (CFS)(CFS)The flow rate or discharge equal to one cubic foot (of water, usually) per second. This rate is equivalent to approximately 7.48 gallons per second.
Cubic foot per second (cfs or ft3/s)As a rate of streamflow, a cubic foot of water passing a reference section in one second of time. A measure of a moving volume of water (1 cfs = 0.
Cultural HeritageThe cultural resources that reflect the nation's maritime history and traditional cultural connections to the sea, as well as the uses and values they…
Cultural ResourceA tangible entity that is valued by or significantly representative of a culture, or that contains significant information about a culture.
Cultural resource(s)Any building, site, district, structure, or object significant in history, architecture, archeology, culture, or science.
CulvertA pipe or small bridge for drainage under a road or structure. A conduit for the free passage of surface drainage water under a highway, railroad, canal…
Curb stop (curb cock)A water service shutoff valve located in a water service pipe near the curb and between the water main and the building.
Current (I)The movement of electrons through a conductor, measured in amperes.
Current MeterDevice used to measure the water velocity or current in a river.
Curtain DrainA drain constructed at the upper end of the area to be drained, to intercept surface or ground water flowing toward the protected area from higher ground…
Curtain groutingThe process of pressure grouting deep holes under a dam or in an abutment to form a watertight barrier and effectively seal seams, fissures, fault zones…
CutoffAn impervious construction by means of which water is prevented from passing through foundation material.
Cutoff TrenchAn excavation later to be filled with impervious material to form a cutoff. Sometimes used incorrectly to describe the cutoff itself.
Cutoff trench (keyway)An excavation in the foundation of an embankment dam, usually located upstream of the dam axis or centerline crest which extends to bedrock or to an…
Cutoff WallA wall of impervious material (e.g., concrete, asphaltic concrete, timber, steel sheet piling, or impervious grout curtain) located in the foundation…
CuttingA detached plant part that, with appropriate treatment, can regenerate into a complete plant.
CWAClean Water Act, California Waterfowl Association.
CycleIn alternating current, the current goes from zero potential or voltage to a maximum in one direction, back to zero, and then to a maximum potential or…
CyclingPowerplant operation to meet the intermediated portion of the load (9 to 14 hours per day).
Cyclopean damA gravity dam in which the mass masonry consists primarily of large one-man or derrick stone embedded in concrete.
Cylinder gateA gate that resembles a large barrel, reinforced to withstand external pressure, with no top or bottom.
Daily Flood PeakThe maximum mean daily discharge occurring in a stream during a given flood event.
DamA structure for impeding and controlling the flow of water in a water course, and which increases the water elevation to create the hydraulic head.
Dam FailureCatastrophic type of failure characterized by the sudden, rapid, and uncontrolled release of impounded water.