NPDP Dam Dictionary

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Term AKA Definition
Epifauna Animals which live on the benthos.
Epilimnion The upper layer of a lake or reservoir with essentially uniform warmer temperatures. See stratification.
Erode To wear away or remove the land surface by wind, water, or other agents.
Erosion A gradual wearing away of soil or rock by running water, waves, or wind. Concrete surface disturbance caused by cavitation, abrasion from moving particles in water, impact of pedestrian or vehicular traffic, or impact of iceflows. Surface displacement of soil caused by weathering, dissolution, abrasion, or other transporting.
Escapement Unharvested spawning stocks that return to the streams.
Escarpment A cliff or steep slope that separates two level or gently sloping areas.
Esthetics An emotional judgment about what is beautiful or pleasing.
Eutrophic Nutrient enrichment of a body of water that contains more organic matter than existing biological oxidization processes can consume. A body of water which has become, either naturally or by pollution, rich in nutrients and often seasonally deficient in dissolved oxygen.
Eutrophication A process where more organic matter is produced than existing biological oxidization processes can consume.
Evaporation Water losses to vapor from water surfaces, sprinkler irrigation, etc.
Excavation The action or process of excavating (to dig or remove earth). See common excavation, rock excavation, and unclassified excavation.
Excess capacity Power generation capacity available on a short- term basis that exceeds the firm energy on a long-term contract offered to an electricity customer.
Excess land Irrigable land, other than exempt land, owned by any landowner in excess of the maximum ownership entitlement under applicable provision of reclamation law.
Exclusive flood control capacity The reservoir capacity assigned to the sole purpose of regulating flood inflows to reduce flood damage downstream. In some instances, the top of exclusive flood control capacity is above the maximum controllable water surface elevation. See flood control capacity.
Exempt land Irrigation land in a district to which the acreage limitation and pricing provisions of Reclamation law do not apply.
Existence value Value people place on simply knowing an area or feature continues to exist in a particular condition.
Existing ground The earth's surface as it is prior to any work. See original ground surface.
Exit channel See outlet channel.
Exotic species A non-native species that is introduced into an area.
Expansion joint A separation between adjoining parts of a concrete structure which is provided to allow small relative movements, such as those caused by temperature changes, to occur independently. A flexible filler is provided in the joint, reinforcement does not pass through the joint.
Exploit Excavate in such a manner as to utilize material in a particular vein or layer, and waste or avoid surrounding material.
Extirpated species A species rendered extinct in a given area.