NPDP Dam Dictionary

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Term AKA Definition
Landholder A landholder is an individual or legal entity owning or leasing land subject to the acreage limitation provisions.
Lateral A channel that conveys water from a canal to a farm, municipality, etc.
Latitude The latitude at the dam centerline as a single value in decimal degrees (e.g., 49.75).
Leaching field A lined or partially lined underground pit into which raw household water (sewage) is discharged and from which the liquid seeps into the surrounding soil. Also called a leaching cesspool.
Leakage Free flow loss of water through a hole or crack.
Lease of power privilege Contractual right given to a non-Federal entity to utilize, consistent with project purposes, water power head and storage from Reclamation projects for electric power generation.
Left abutment See abutment.
Left or Right Designation The designation of left or right is made with the observer looking downstream.
Length of dam See crest length.
Lentic Standing waters, such as lakes, ponds, and marshes.
Levee See dike.
Life cycle Various stages an animal passes through from egg fertilization to death.
Lift A step or bench in a multiple layer excavation or fill.
Lift line Horizontal construction joint created when new concrete is placed on previously placed concrete.
Limnological conditions Conditions on freshwater lakes.
Limnology Scientific study of the physical characteristics and biology of lakes, ponds, and streams.
Lineament A rectilinear topographic feature.
Lining Any protective material used to line the interior surface of a conduit, pipe, or tunnel. With reference to a canal, tunnel or shaft, a coating of asphaltic concrete, concrete, reinforced concrete, or shotcrete to provide watertightness, to prevent erosion, or to reduce friction.
Liquefaction When a solid form is turned into a liquid form. During an earthquake, low density materials act like water and lose their supporting strength.
Liquid limit The water content corresponding to the arbitrary limit between the liquid and plastic states of consistency of a soil; the water content at which a pat of soil, cut by a groove of standard dimensions, will flow together for a distance of 1/2 inches under the impact of 25 blows in a standard liquid limit apparatus.
Littoral Pertaining to the shore.
Live capacity Live Storage That part of the total reservoir capacity which can be withdrawn by gravity. This capacity is equal to the total capacity less the dead capacity.
Load Amount of electrical capacity or energy delivered at a given point. The power output of an engine or powerplant under given circumstances.
Load factor The ratio of an average load to the maximum load.
Loess Wind-deposited silt.
Loessial Medium-textured materials (usually silt or very fine sand) transported and deposited by wind action. These materials may be deposited in depths ranging from less than 1 foot to well over 100 feet.
Log boom A floating structure used to protect the face of a dam by deflecting floating material and waves away from the dam. A device used to prevent floating debris from obstructing spillways and intakes.
Logbook A dated, written record of performed operation and maintenance items or observations pertinent to a structure.
Long-throated flumes Long-throated flumes control discharge rate in a throat that is long enough to cause nearly parallel flow lines in the region of flow control. Parallel flow allows these flumes to be accurately rated by analysis using fluid flow concepts. Long-throated flumes can have nearly any desired cross-sectional shape and can be custom fitted into most canal-site geometries. The Ramp flume, also considered a version of broad-crested weir, is an example of this kind of flume.
Longitude The longitude at the dam centerline as a single value in decimal degrees (e.g., -140.15).