Water — page 18 of 31

Water terms

1701. Juvenile salmon All early lifestages of downstream migrating salmon (fry through smolt).
1702. Juvenile Water Water formed chemically within the earth and brought to the surface in intrusive rock.
1703. Kilo A prefix meaning "thousand".
1704. Kilovolt (kV) One thousand volts.
1705. Kilovolt-Ampere (kVa) A unit of apparent power, equal to 1,000 volt-amperes; the mathematical product of the volts and amperes in an electrical circuit.
1706. Kilowatt (kW) (kW) A standard unit of electrical power equal to one thousand watts, or to the energy consumption at a rate of 1000 Joules per second.
1707. Kilowatt hour (kWh) (kWh) A measure of energy equivalent to the expenditure of one kilowatt for one hour. For example, 1 kWh will light a 100-watt light bulb for 10 hours.
1708. Kinetic Energy Energy available as a result of motion that varies directly in proportion to an object's mass and the square of its velocity.
1709. Laccolith An igneous intrusion that has been forced between two layered rock units. The top of the intrusion is arched upwards and the bottom of the intrusion is…
1710. Lacustrine habitat Lake or reservoir wetland habitat.
1711. Lag (of a basin) The measure of the time between the center of mass of precipitation to the center of mass of runoff (on the hydrograph); basin lag is a function of not…
1712. Lag (Time) The time it takes a flood wave to move downstream.
1713. Lagging In tunneling, planking placed against the dirt or rock walls and ceiling, outside the ribs.
1714. Lagomorphs The order of mammals including rabbits, hares, and pikas.
1715. Laminar Flow Flow in which the head loss is proportional to the first power of the velocity.
1716. Land classification Reclamation's systematic placing of lands into classes based on their suitability for sustained irrigated farming.
1717. Land ownership Land held in title.
1718. Land retirement Permanent removal of land from agricultural production.
1719. Landfill An open area where trash is buried. Facility in which solid waste from municipal and/or industrial sources is disposed; sanitary landfills are those that…
1720. Landholder A landholder is an individual or legal entity owning or leasing land subject to the acreage limitation provisions.
1721. Landslide The failure of a sloped bank of soil or rock in which the movement of the mass takes place along a surface of sliding.
1722. LARC (Limited Automatic Report Collector) An electronic device that interfaces a river or precipitation gage with a telephone line making it possible for remote computers to call a gaging site and…
1723. Large Marine Ecosystems Regions of ocean space encompassing coastal areas from the river basins and estuaries out to the seaward boundary and continental shelves and to the…
1724. Larval fish An immature stage that develops from the fertilized egg before assuming the characteristics of the adult.
1725. Lasting For purposes of national system natural heritage and cultural heritage MPAs, the site's authority must clearly state its intent to provide permanent…
1726. Lateral A channel that conveys water from a canal to a farm, municipality, etc.
1727. Lateral moraine Ridge-like pile of sediment along the side of a glacier.
1728. Lava Magma that reaches the Earth's surface and issues from volcanoes.
1729. Leach To remove components from the soil by the action of water trickling through.
1730. Leachate A liquid that results from water collecting contaminants as it trickles through wastes, agricultural pesticides or fertilizers.
1731. Leaching Removal of soluble material from soil or other permeable material by the passage of water through it.
1732. Leaching field (leaching cesspool) 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.
1733. Leaching requirement Quantity of irrigation water required for transporting salts through the soil profile to maintain a favorable salt balance in the root zone for plant…
1734. Lead time Time available for Decision Makers to determine if conditions at a dam and reservoir, or in the basin, warrant declaration of a specific emergency…
1735. Leak Uncontrolled loss of water by flow through a hole or crack.
1736. Leakage Free flow loss of water through a hole or crack.
1737. 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…
1738. Left Abutment See abutment.
1739. Left or right designation In the context of dams and river channels, the designation of left or right is made with the observer looking in the downstream direction.
1740. Leg A side post in tunnel timbering.
1741. Length The distance in the direction of flow between two specific points along a river, stream, or channel.
1742. Length of dam. See crest length.
1743. Lentic Still water systems such as lakes and reservoirs.
1744. Lentic System A nonflowing or standing body of fresh water, such as a lake or pond. Compare lotic system.
1745. Letter of Agreement (LOA). See Memorandum of Understanding (MOU).
1746. Levee A natural or man-made barrier that helps keep rivers from overflowing their banks. See dike.
1747. Levee (Dike) A long, low embankment usually built along a watercourse to protect land from flooding.
1748. Level The number of values used in a card counting system. A level one counting system only uses +1 and -1, but a level two system would use +1, +2, -1 and -2…
1749. Level of protection (LOP) As used in the evaluation process, it is the level of loading selected to which corrective actions will be designed to prevent dam failure.
1750. LFWS A generic term for any type of Local Flood Warning System.
1751. life cycle The sequence of events from a given developmental stage in one generation to the same stage in the following generation.
1752. Lift The force that pulls a wind turbine blade, as opposed to drag.
1753. Lift line Horizontal construction joint created when new concrete is placed on previously placed concrete.
1754. Limestone A sedimentary rock made mostly of the mineral calcite (calcium carbonate). Limestone is usually formed from shells of once-living organisms or other…
1755. Limited Automatic Remote Collector (LARC) (LARC) An electronic device that interfaces a river or precipitation gage with a telephone line making it possible for remote computers to call a gaging site and…
1756. Limnological conditions Conditions on freshwater lakes.
1757. Limnology Scientific study of the physical characteristics and biology of lakes, ponds, and streams.
1758. Line item A specified amount in a budget to spend on a particular activity.
1759. Lineament A straight topographic feature of regional extent that is thought to represent crustal structure.
1760. Lining Any protective material used to line the interior surface of a conduit, pipe, or tunnel.
1761. Liquefaction Enzymatic digestion (often by alpha-amylase) of gelatinized starch to form lower molecular weight polysaccharides.
1762. Liquid limit (LL) The moisture content corresponding to the arbitrary limit between the liquid and plastic states of consistency of a soil.
1763. List of National System MPAs The List of National System MPAs is the official inventory of all MPAs that have been formally recognized as part of the national system.
1764. Lithosphere That part of the earth which is composed predominantly of rocks (either coherent or incoherent, and including the disintegrated rock materials known as…
1765. Littoral Pertaining to the shore.
1766. Littoral Zone The zone or strip of land along the shoreline between the high and low water marks.
1767. Live Capacity The total amount of storage capacity available in a reservoir for all purposes, from the dead storage level to the normal water or normal pool level…
1768. 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.
1769. Load Commissions charged on the purchase or sale of mutual fund units.
1770. Load factor The ratio of average energy demand (load) to maximum demand (peak load) during a specific period.
1771. Load following The generating capacity having fast response time to varying loads over a wide range of unit loading by automatic generation control (AGC) from load…
1772. Loam A soil consisting of an easily crumbled mixture of clay, silt, and sand.
1773. Local capabilities assessment Evaluation and report performed by members of the Early Warning System design team and/or community planners to assess the warning and evacuation…
1774. Local emergency operations plan (LEOP) A general planning document, required by law, that describes the responsibilities and actions to be performed in the event of an emergency and/or disaster…
1775. Local emergency planning committee (LEPC) A committee made up of local officials, citizens, and industry representatives charged with development and maintenance of emergency response plans for…
1776. Local Flood Warning System (LWFS) (LWFS) A general designator for a network of stream and rain gages implemented by a community or local government to monitor hydrologic events as they occur.
1777. Local Flooding Flooding conditions over a relatively limited (localized) area.
1778. Local Government A legally-established unit of government at a level below state or territory government, including but not limited to, county, city, town, or village.
1779. Local officials/authorities The personnel authorized by election or job title to carry out the operation, planning, mitigation, preparedness, response, and recovery functions of the…
1780. Local organization The local government agency or office having the principal or lead role in emergency planning and preparedness.
1781. Local runoff Water running off a local area, such as rainfall draining into a nearby creek.
1782. Lockout Lockout means a labor dispute involving a work stoppage, wherein an employer withholds work from its employees in order to gain a concession from them.
1783. Lockout device A device that utilizes a positive means such as a lock, either key or combination type, to hold an energy isolating device in the safe position and…
1784. Loess A group of windblown soils, largely comprising silt, weakly cemented by calcite.
1785. Loessial Medium-textured materials (usually silt or very fine sand) transported and deposited by wind action.
1786. Log and Safety Boom A net-like device installed in a reservoir, upstream of the principal spillway, to prevent logs, debris and boaters from entering a water discharge…
1787. Log boom A floating structure used to protect the face of a dam by deflecting floating material and waves away from the dam.
1788. Logbook (operating log) A dated, written record of performed operation and maintenance items or observations pertinent to a structure.
1789. Long Term Storage Dams Reservoirs used for recreational use or storage of irrigation, municipal or industrial water.
1790. 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.
1791. Longitudinal Pertaining to or extending along the long axis, or length, of a structure. Lengthwise. See transverse.
1792. Loose yards Measurement of soil or rock after it has been loosened by digging or blasting.
1793. Losing stream A stream or reach that contributes water to a zone of saturation.
1794. Lotic Moving water systems such as streams and rivers.
1795. Lotic System A flowing body of fresh water, such as a river or stream. Compare lentic system.
1796. Low dam A dam up to 100 feet high. See medium-height dam and high dam.
1797. Low density material A material having a low weight per unit volume either as it occurs in its natural state or after compacting it, such as loess with a density of 80 pounds…
1798. Low hazard A downstream hazard classification for dams in which no lives are in jeopardy and minimal economic loss (undeveloped agriculture, occasional uninhabited…
1799. Low-head hydroelectric Hydroelectric power that operates with a head of 20 meters (approximately 66 feet) or less.
1800. Low-Level Outlet (Drain, Bottom Outlet or Sluiceway) An opening at a low level from a reservoir generally used for emptying or for scouring sediment and sometimes for irrigation releases.