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ALKALINE: Sometimes water or soils contain an amount of alkali (strongly basic) substances sufficient to raise the pH value above 7.0 and be harmful to the growth of crops.

ALLUVIAL: An adjective referring to soil or earth material which has been deposited by running water, as in a riverbed, flood plain, or delta.

AQUEDUCT: A pipe, conduit, or channel designed to transport water from a remote source, usually by gravity.

AQUIFER: A geologic formation, a group of formations, or a part of a formation that is water bearing. A geological formation or structure that stores or transmits water, or both, such as to wells and springs. Use of the term is usually restricted to those water-bearing structures capable of yielding water in sufficient quantity to constitute a usable supply.

AQUIFER, CONFINED: An aquifer which is bounded above and below by formations of impermeable or relatively impermeable material. An aquifer in which ground water is under pressure significantly greater than atmospheric and its upper limit is the bottom of a bed of distinctly lower hydraulic conductivity than that of the aquifer itself. See Artesian Aquifer.

ARTESIAN PRESSURE: The pressure under which Artesian Water in an Artesian Aquifer is subjected, generally significantly greater than atmospheric.

ARTESIAN WATER: Ground water that is under pressure when tapped by a well and is able to rise above the level at which it is first encountered. It may or may not flow out at ground level. The pressure in such an aquifer commonly is called Artesian Pressure, and the formation containing artesian water is an Artesian Aquifer or Confined Aquifer.

ARTESIAN WELL: (1) A well bored down to the point, usually at great depth, at which the water pressure is so great that the water is forced out at the surface. The name is derived from the French region of Artois, where the oldest well in Europe was bored in 1126. (2) A well tapping a Confined or Artesian Aquifer in which the static water level stands above the top of the aquifer. The term is sometimes used to include all wells tapping confined water. Wells with water levels above the unconfined water table are said to have positive artesian head (pressure) and those with water level below the unconfined water table, negative artesian head. If the water level in an artesian well stands above the land surface, the well is a Flowing Artesian Well. If the water level in the well stands above the water table, it indicates that the artesian water can and probably does discharge to the unconfined water body.

ARTESIAN ZONE: A zone where water is confined in an aquifer under pressure so that the water will rise in the well casing or drilled hole above the bottom of the confining layer overlying the aquifer.

ARTIFICIAL RECHARGE: The designed (as per man's activities as opposed to the natural or incidental) replenishment of ground water storage from surface water supplies such as irrigation or induced infiltration from streams or wells. There exist five (5) common techniques to effect artificial recharge of a ground water basin:

  1. Water Spreading consisting of the basin method, stream-channel method, ditch method, and flooding method, all of which tend to divert surface water supplies to effect underground infiltration;
  2. Recharge Pits designed to take advantage of permeable soil or rock formations;
  3. Recharge Wells which work directly opposite of pumping wells, although they generally have limited scope and are better used for deep, confined aquifers;
  4. Induced Recharge which results from pumping wells near surface supplies, thereby inducing higher discharge towards the well; and
  5. Wastewater Disposal which includes the use of secondary treatment wastewater in combination with spreading techniques, recharge pits, and recharge wells to reintroduce the water into deep aquifers thereby both increasing the available ground water supply and also further improving the quality of the wastewater. Also referred to as Induced Recharge. Also see Natural Recharge, Incidental Recharge, Injection, and Perennial Yield.

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BENCH: A long, narrow, relatively level terrace or platform breaking the continuity of a slope.

BIODIVERSITY: Refers to the variety and variability of life, including the complex relationships among microorganisms, insects, animals, and plants that decompose waste, cycle nutrients, and create the air that we breathe. For biological diversity, these items are organized at many levels, ranging from complete Ecosystems to the biochemical structures that are the molecular basis of heredity.

BIOLOGICAL ASSESSMENT: Under Section 7 of the Endangered Species Act, the information prepared by or for FWS for an action area and the evaluated potential effects of the action on proposed/listed species or habitat. (50 C.F.R. 402.02)

BIOLOGICAL OPINION: Under Section 7 of the Endangered Species Act, a document stating the opinion of FWS or NMFS on whether or not a federal action is likely to jeopardize the continued existence of listed species, or result in the destruction or adverse modification of critical habitat. [50 C.F.R. 424.02; Handbook Section 4.5 (A)]

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CONDENSATION: The process of water vapor in the air turning into liquid water. Water drops on the outside of a cold glass of water are condensed water. Condensation is the opposite process of evaporation.

CRITICAL HABITAT: (1) The specific areas within the geographic area occupied by the species, at the time it is listed, where those physical features are essential to the conservation of the species, and which may require special management considerations or protection; and (2) the specific areas outside the geographic area occupied by the species at the time it is listed upon a determination by the Secretary that such areas are essential to the conservation of the species. [16 U.S.C 1532 (5)]

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DISSOLVED OXYGEN:Oxygen is measured in its dissolved form as dissolved oxygen (DO). If more oxygen is consumed than is produced, DO levels decline and some sensitive animals may move away, weaken, or die. Cold water holds more oxygen than warm water and water holds less oxygen at higher altitudes.

DRAINAGE BASIN: Land area where precipitation runs off into streams, rivers, lakes, and reservoirs. It is a land feature that can be identified by tracing a line along the highest elevations between two areas on a map, often a ridge. Also called a “watershed”.

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EFFLUENT: Water that flows from a sewage treatment plant after it has been treated.

ELECTRICAL CONDUCTIVITY: Electrical conductivity (conductivity) is a measure of the ability of water to pass an electrical current. Conductivity in water is affected by the presence of inorganic dissolved solids such as chloride, nitrate, sulfate, and phosphate anions (ions that carry a negative charge) or sodium, magnesium, calcium, iron, and aluminum cations (ions that carry a positive charge). Organic compounds like oil, phenol, alcohol, and sugar do not conduct electrical current very well and therefore have a low conductivity when in water. Conductivity is also affected by temperature: the warmer the water, the higher the conductivity.

ENDANGERED SPECIES: Under the Endangered Species Act, any species (including subspecies) which is in danger of extinction throughout all or a significant portion of its range. [Section 3(6) of Act; 16 U.S.C. 1532(6)]

ENDANGERED SPECIES ACT OF 1973 (ESA): 16 U.S.C. 1513-1543; the federal law that provides a means for conserving ecosystems upon which endangered species and threatened species depend and that provides a program for the conservation of such endangered and threatened species. (16 U.S.C. 1531)

ENVIRONMENTAL ASSESSMENT (EA): A concise public document prepared in compliance with National Environmental Policy Act. Briefly discusses the need for an action and alternatives to such action, and provides sufficient evidence and analysis to determine whether to prepare an Environmental Impact Statement or Finding of No Significant Impact. (40 C.F.R. 1508.9)

ENVIRONMENTAL IMPACT STATEMENT (EIS): A detailed written statement, required by Section 102(2)(c) of the National Environmental Policy Act. Analyzes the environmental impacts of a proposed action, adverse effects that cannot by avoided, alternative courses of action, short-term uses of the environment versus the maintenance of enhancement of long-term productivity, and any irreversible and irretrievable commitment of resources. (40 C.F.R. 1508.11)

EROSION: The process in which a material is worn away by a stream of liquid (water) or air, often due to the presence of abrasive particles in the stream.

EVAPORATION: The process of liquid water becoming water vapor, including vaporization from water surfaces, land surfaces, and snow fields, but not from leaf surfaces.

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FLOOD: An overflow of water onto lands that are used or usable by man and not normally covered by water. Floods have two essential characteristics: The inundation of land is temporary; and the land is adjacent to and inundated by overflow from a river, stream, lake, or ocean.

FLOOD, 100-YEAR: A 100-year flood does not refer to a flood that occurs once every 100 years, but to a flood level with a 1 percent chance of being equaled or exceeded in any given year.

FLOOD PLAIN: A strip of relatively flat and normally dry land alongside a stream, river, or lake that is covered by water during a flood.

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GREYWATER: Wastewater from clothes washing machines, showers, bathtubs, hand washing, lavatories and sinks.

GROUND WATER: (1) Water that flows or seeps downward and saturates soil or rock, supplying springs and wells. The upper surface of the saturate zone is called the water table. (2) Water stored underground in rock crevices and in the pores of geologic materials that make up the Earth’s crust.

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HABITAT: The location where a particular plant or animal lives and its surroundings, both living and non-living. Includes the presence of a group of particular environmental conditions surrounding an organism including air, water, soil, mineral elements, moisture, temperature, and topography.

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IMPERMEABLE LAYER: A layer of solid material, such as rock or clay, which does not allow water to pass through.

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LISTED SPECIES: A threatened or endangered species that receives the legal protection of the Endangered Species Act of 1973.

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MITIGATION: To moderate, reduce or alleviate the impacts of a proposed activity. Includes, in order: (1) avoiding the impact by not taking a certain action or parts of an action; (2) minimizing impacts by limiting the degree or magnitude of action and its implementation; (3) rectifying the impacts by restoring, rehabilitating, or repairing the affected environment; (4) reducing or eliminating impacts over time by preservation and maintenance operations during the life of the action; (5) compensating for the impact by replacing or providing substitute resources or environments. (40 C.F.R. 1508.20)

MUNICIPAL WATER: Municipal water may come from either ground water or surface water sources. Once water has entered a municipal water system, from whatever source, it will be considered municipal water.

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NATURAL RECHARGE: The replenishment of ground water storage from naturally-occurring surface water supplies such as precipitation and stream flows. Also see Artificial (or Induced) Recharge, Incidental Recharge, and Perennial Yield.

NON-POINT SOURCE (NPS) POLLUTION: Pollution discharged over a wide land area, not from one specific location. These are forms of diffuse pollution caused by sediment, nutrients, organic and toxic substances originating from land-use activities, which are carried to lakes and streams by surface runoff. Non-point source pollution is contamination that occurs when rainwater, snowmelt, or irrigation washes off plowed fields, city streets, or suburban backyards. As this runoff moves across the land surface, it picks up soil particles and pollutants, such as nutrients and pesticides.

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OVERDRAFT: That quantity of water pumped in excess of the safe yield; the act of overdrawing a water supply or aquifer in amounts greater than replenishment. Also, the sustained extraction of ground water from an aquifer at a rate greater than the recharge rate of the aquifer, resulting in a drop in the level of the water table.

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pH: A shorthand designation for the concentration of hydronium or hydrogen ions in a solution, defined as the negative log of the concentration of hydronium ions.

PERMEABILITY: The ability of a material to allow the passage of a liquid, such as water through rocks. Permeable materials, such as gravel and sand, allow water to move quickly through them, whereas impermeable material, such as clay, doesn’t allow water to flow freely.

POINT BAR: One of a series of low, arcuate ridges of sand and gravel developed on the inside of a growing meander by the slow addition of individual accretions accompanying migration of the channel toward the outer bank.

POINT-SOURCE POLLUTION: Water pollution coming from a single point, such as a sewage-outflow pipe.

POTABLE WATER: Water of a quality suitable for drinking.

PUBLIC WATER USE: Water supplied from a public-water supply and used for such purposes as firefighting, street washing, and municipal parks and swimming pools.

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RECHARGE: Water added to an aquifer. For instance, rainfall that seeps into the ground.

RECLAIMED WASTEWATER: Treated wastewater that can be used for beneficial purposes, such as irrigating certain plants.

RIPARIAN: Areas adjacent to rivers and streams with plants adapted to moist growing conditions found along waterways and shorelines. They are frequently important to wildlife habitat because of their greater density and succulence.

RUNOFF: (1) That part of the precipitation, snow melt, or irrigation water that appears in uncontrolled surface streams, rivers, drains or sewers. Runoff may be classified according to speed of appearance after rainfall or melting snow as direct runoff or base runoff, and according to source as surface runoff, storm inter flow, or ground water runoff. (2) The total discharge described in (1), above, during a specified period of time. (3) Also defined as the depth to which a drainage area would be covered in all of the runoff for a given period of time were uniformly distributed over it.

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SEEPAGE: (1) The slow movement of water through small cracks, pores, Interstices, etc., of a material into or out of a body of surface or subsurface water. (2) The loss of water by infiltration into the soil from a canal, ditches, laterals, watercourse, reservoir, storage facilities, or other body of water, or from a field.

SPECIES: This term includes any subspecies of fish or wildlife or plants, and any distinct population segment of any species of vertebrate fish or wildlife which interbreeds when mature.& [16 U.S.C. 1532 (16)]

SURFACE WATER: Water that is on the Earth’s surface, such as in a stream, river, lake, or reservoir.

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THREATENED SPECIES: Under the Endangered Species Act, this term is defined as "any species which is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range." [16 U.S.C. 1532 (20)]

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WASTEWATER: Water that has been used in homes, industries, and businesses that is not for reuse unless it is treated.

WATER CYCLE: The circuit of water movement from the oceans to the atmosphere and to the Earth and return to the atmosphere through various stages or processes such as precipitation, interception, runoff, infiltration, percolation, storage, evaporation, and transportation.

WATER RESOURCES: The supply of ground water and surface water in a given area.

WATER TABLE: The level of ground water; the upper surface of the Zone of Saturation for underground water. It is an irregular surface with a slope or shape determined by the quantity of ground water and the permeability of the earth material. In general, it is highest beneath hills and mountains and lowest beneath valleys. Also referred to as Ground Water Table.

WATERSHED: The land area that drains water to a particular stream, river, or lake. It is a land feature that can be identified by tracing a line along the highest elevations between two areas on a map, often a ridge. Large watersheds, like the Mississippi River basin contain thousands of smaller watersheds.

WATER WORDS: For more water words, please visit The Department of Conservation and Natural Resources at http://www.state.nv.us

WETLAND OBLIGATE: Species that only appear in riparian and wetland habitats and are dependent upon them for breeding and survival.

WETLANDS: An area that is inundated or saturated by surface water or ground water at a frequency and duration sufficient to support, and that under normal circumstances does support vegetation typically adapted for life in saturated soil conditions. Wetlands include swamps, marshes, bogs and similar areas.

Las Vegas Wash Project Coordination Team • 100 City Parkway, Suite 700 • Las Vegas, NV 89106 • (702) 822-3300