Water — page 11 of 31

Water terms

1001. Easement A right to the use of, or access to, land owned by another.
1002. ECC Eastern Colorado Area Office (Loveland, CO).
1003. Ecological Network A set of discrete MPAs within a region that are connected through dispersal of reproductive stages (eggs, larvae, spores, etc.
1004. Ecological Resilience The capacity of an ecosystem or natural population to resist or recover from major changes in structure and function following natural and human-caused…
1005. Ecology The study of the interactions of organisms with their environment and with each other.
1006. Economic analysis A procedure that includes both tangible and intangible factors to evaluate various alternatives.
1007. Ecosystem A complex ecological community or environment forming a functioning whole.
1008. Eddy Circular current of water moving against the main current. See recirculation zone.
1009. Edison Electric Institute (EEI) The Edison Electric Institute is an association of electric companies formed in 1933 "to exchange information on industry developments and to act as an…
1010. EEO equal employment opportunity.
1011. Effective diameter Particle diameter corresponding to 10 percent finer on the accumulative gradation curve.
1012. Effective force The force transmitted through a soil or rock mass by intergranular pressures.
1013. Effective peak ground acceleration That acceleration which is most closely related to structural response and to damage potential of an earthquake.
1014. Effective Porosity The ratio of the volume of a soil or rock mass that can be drained by gravity to the total volume of the mass.
1015. Effective Precipitation (Rainfall) (1) That part of the precipitation that produces runoff. (2) A weighted average of current and antecedent precipitation that is "effective" in correlating…
1016. Efficiency Under the First Law of Thermodynamics, efficiency is the ratio of work or energy output to work or energy input, and cannot exceed 100 percent.
1017. Effluent The treated waste water discharged by sewage treatment plants.
1018. Effluent limitation The maximum amount of a specific substance or characteristic that can be present in effluent discharge without violating water quality standards in…
1019. Effluent Seepage Diffuse discharge of ground water to the ground surface.
1020. Effluent Stream Any watercourse in which all, or a portion of the water volume came from the Phreatic zone, or zone of saturation by way of groundwater flow, or baseflow.
1021. EGL - energy grade line.
1022. EIS - Environmental Impact Statement.
1023. Elbow A pipe fitting having two openings which causes a run of pipe to change direction 90 degrees.
1024. Electric plant (physical) A facility containing prime movers, electric generators, and auxiliary equipment for converting mechanical, chemical, and/or fission energy into electric…
1025. Electric power industry The public, private, and cooperative electric utility systems of the United States taken as a whole.
1026. Electric power system Physically connected electric generating, transmission, and distribution facilities operated as a unit under one control.
1027. Electric Utility A corporation, person, agency, authority or other legal entity that owns and/or operates facilities for the generation, transmission, distribution or sale…
1028. Electrical conductivity A measure of the salt content of water.
1029. Electrical demand Energy requirement placed upon a utility's generation at a given instant or averaged over any designated period of time; expressed in kilowatts.
1030. Electromotive force (EMF) The electrical pressure available to cause a flow of current when an electrical circuit is closed. See voltage.
1031. Elevation A drawing of a face of a building with all the features shown, as if in a single vertical plane
1032. Elongate An increase of the vertical diameter of a flexible pipe.
1033. Embankment An earth structure the top of which is higher than the adjoining surface. A shaped earth or rockfill dam.
1034. Embankment Dam (Fill Dam) Any dam constructed of excavated natural materials or industrial waste materials.
1035. Embankment dam or fill dam Any dam constructed of excavated natural materials. See diaphragm-type earthfill, earth dam or earthfill dam, homogeneous earthfill dam, hydraulic fill…
1036. Emergency A serious situation that happens unexpectedly and demands immediate action.
1037. Emergency Action Plan A predetermined plan of action to be taken to reduce the potential for property damage and loss of lives in an area affected by a dam break or excessive…
1038. Emergency action plan (EAP) Reclamation procedures for dam operating personnel to follow during emergency situations or unusual occurrences at a given dam to reduce potential for…
1039. Emergency broadcast system A federally established network of commercial radio stations that voluntarily provide official emergency instructions or directions to the public during…
1040. Emergency classification levels A phased system in which dam operating organizations classify dam safety emergency incidents into response levels according to how severe they are at the…
1041. Emergency evacuation zones Geographical areas delineated in inundation areas downstream from a dam (hazard generator) that define the potential area of impact and allow prioritizing…
1042. Emergency Exercise An activity designed to promote emergency preparedness; evaluate emergency operations, policies, plans, procedures, and facilities; train personnel in…
1043. Emergency Gate A standby or auxiliary gate used when the normal means of water control is not available.
1044. Emergency management The system by which mitigation, preparedness, response, and recovery activities are undertaken to save lives and protect property from all hazards.
1045. Emergency management agency Any State or local agency responsible for emergency operations, planning, mitigation, preparedness, response, and recovery for all hazards.
1046. Emergency on-scene coordinator (Reclamation OSC) At all times, there must be at least one employee either on the premises or on call (i.e.
1047. Emergency operations center The location of facility where responsible officials gather during an emergency to direct and coordinate emergency operations, to communicate with other…
1048. Emergency operations plan (State and local) A plan, usually developed in accord with guidance contained in the Guide for the Development of State and Local Emergency Operations Plans, Civil…
1049. Emergency Preparedness Plan (EPP) Predecessor to the term Emergency Action Plan (EAP).
1050. Emergency program manager The individual responsible on a day-to-day basis for a jurisdiction's effort to develop a capability for coordinated response to and recovery from the…
1051. Emergency reserve fund Money reserved or required by contract to be reserved by an operating entity for use in emergency situations involving facilities under the entity's…
1052. Emergency Services Evaluation of an emergency medical condition and treatment to keep the condition from getting worse.
1053. Emergency Spillway A spillway which provides for additional safety should emergencies not contemplated by normal design assumptions be encountered, i.e.
1054. End moraine (terminal moraine) Ridge of sediment piled at the front edge of a glacier.
1055. Endangered species A plant or animal species in immediate danger of extinction because its population number has reached a critical level, or its habitat has been…
1056. Endangered species act (ESA) This act provides a framework for the protection of endangered and threatened species. See Endangered Species Act of 1973.
1057. Energy The capability of doing work; different forms of energy can be converted to other forms, but the total amount of energy remains the same.
1058. Energy Dissipator A device constructed in a waterway to reduce the kinetic energy of fast flowing water. See stilling basin.
1059. Energy grade line (EGL) (energy line, energy gradient) The line showing the total energy at any point in a pipe. The total energy in the flow of the section with reference to a datum line is the sum of the…
1060. Energy Policy Act (EPACT) Comprehensive federal legislation enacted in 1992 that is resulting in fundamental changes in the electric utility industry by promoting competion in…
1061. Energy source The primary source that provides the power that is converted to electricity through chemical, mechanical, or other means.
1062. Engineer's Level A telescope which is attached to a spirit-tube level, all revolving around a vertical axis and is mounted on a tripod.
1063. Enhancement Improvement of a facility beyond its originally designed purpose or condition.
1064. Enhancement flow Improved flows that result in better stream conditions for aquatic, terrestrial, and other resources.
1065. Ensemble Hydrologic Forecasting A process whereby a continuous hydrologic model is successively executed several times for the same forecast period by use of varied data input scenarios…
1066. Ensign valve Earliest type of Reclamation needle valve (named after Reclamation's chief electrical engineer), operated by water pressure from the forebay, and mounted…
1067. Entrain To trap bubbles in water either mechanically through turbulence or chemically through a reaction.
1068. Entrainment The incorporation of fish, eggs, larvae, and other plankton with intake water flow entering and passing through a cooling water intake structure and into…
1069. Environment All the natural and living things around us. The earth, air, weather, plants, and animals all make up our environment.
1070. Environmental analysis Systematic process for consideration of environment factors in land management actions.
1071. Environmental Assessment (EA) (EA) A public document that analyzes a proposed federal action for the possibility of significant environmental impacts.
1072. Environmental Impact Statement (EIS) (EIS) A comprehensive study of likely environmental impacts resulting from major federally-assisted projects; statements are required by the National…
1073. Environmental Protection Agency (EPA) (EPA) Environmental Protection Agency (EPA) was established as an independent agency on December 2, 1970 during President Nixon's term in office.
1074. Eolian Refers to the processes of wind erosion, transport, and deposition. For example, sand dunes are landforms produced by eolian processes in arid…
1075. EPACT - Energy Policy Act.
1076. Ephemeral creek A creek or stream that flows briefly only in direct response to precipitation and whose channel is above the water table. See intermittent stream.
1077. Epicenter Focal point on the earth's surface directly above the origin of a seismic disturbance.
1078. Epifauna Animals which live on the benthos.
1079. Epilimnion The warm layer of surface water.
1080. Equi-Potential Line A line, in a field of flow, such that the total head is the same for all points on the line, and therefore the direction of flow is perpendicular to the…
1081. Equilibrium Drawdown The ultimate, constant drawdown for a steady rate of pumped discharge.
1082. Equilibrium Surface Discharge The steady rate of surface discharge which results from a long-continued, steady rate of net rainfall, with discharge rate equal to net rainfall rate.
1083. Equilibrium Time The time when flow conditions become substantially equal to those corresponding to equilibrium discharge or equilibrium drawdown.
1084. Equivalent diameter (equivalent size) The diameter of a hypothetical sphere composed of material having the same specific gravity as that of the actual soil particle and of such size that it…
1085. Equivalent fluid A hypothetical fluid having a unit weight such that it will produce a pressure against a lateral support presumed to be equivalent to that produced by the…
1086. Erode To wear away or remove the land surface by wind, water, or other agents.
1087. Erosion The wearing away of land surface by wind or water, intensified by land-clearing practices related to farming, residential or industrial development, road…
1088. Erratic Boulder transported by a glacier and left behind when the ice melted.
1089. ESA See Endangered Species Act of 1973
1090. Escapement Unharvested spawning stocks that return to the streams.
1091. Escarpment A cliff or the steep slopes of a plateau edge.
1092. Essential element Any of a number of elements required by living organisms to ensure normal growth, development and maintenance.
1093. Essential Fish Habitat (EFH) Authorized by the Magnuson-Stevens Fishery Conservation and Management Act, EFH are those waters and substrate necessary to fish for spawning, breeding…
1094. Esthetics An emotional judgment about what is beautiful or pleasing.
1095. Estuary A water body where salt and fresh water meet resulting in brackish water. These areas usually have associated marshlands and are critical nursery and…
1096. Esturine waters Deepwater tidal habitats and tidal wetlands that are usually enclosed by land but have access to the ocean and are at least occasionally diluted by…
1097. Esturine Zone The area near the coastline that consists of estuaries and coastal saltwater wetlands.
1098. Eutrophic Highly fertile waters characterized by warm, nutrient-rich shallow basins.
1099. Eutrophication The natural aging process of water bodies, by siltation and organic decomposition, which reduces both water volume and oxygen levels.
1100. Evacuation The fifth of five Early Warning System components consisting of the plans, personnel, equipment, and facilities needed to move the population at risk to…