A Guide to Commonly Used Water Terms

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acre-foot - a volume of water equal to the amount that would cover one acre to a depth of one foot, or 325,851 gallons. An acre-foot of water is enough to serve a family of five for one year.

aeration - the process of bubbling air through a solution, used in the water treatment  process to remove odors.

Alfred Merritt Smith Water Treatment Facility (AMSWTF) -The Southern Nevada Water System's water treatment facility located near Saddle Island on the shore of Lake Mead. First placed into operation in 1971, the AMSWTF treats and transmits Colorado River water to the Las Vegas Valley.

alluvial - an adjective referring to the process of depositing soil or earth material by running water, as in a riverbed, flood plain or delta.

aqueduct - a pipe or conduit made for conveying water.

aquifer - a layer of underground sand, gravel or porous rock through which water flows slowly. 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.

appropriation - the authorized use of a quantity of water from a well, stream, river or other source for a specific place and manner of use.

artesian well - a well tapping an aquifer underlying an impervious material in which the static water level in the well stands above where it is first encountered in the aquifer.

artesian zone - a well tapping an aquifer underlying an impervious material in which the static water level in the well stands above where it´s first encountered in the aquifer.

artificial groundwater recharge - The process of injecting treated water through a well into the groundwater aquifer.

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banked groundwater recharge - water that has been stored temporarily in the groundwater aquifer through a program of artificial groundwater recharge.

beneficial use - the basis, measure and limit of the right to the use of water. Beneficial uses include municipal, quasi-municipal, commercial, industrial, mining, recreational and irrigation use.

condensation - the changing of a gas or vapor into a liquid.

Clark County Department of Comprehensive Planning - The department of the Clark County government responsible for coordinating certain planning activities for the county, including responsibility for the regional wastewater management plan.

Colorado River Commission (CRC) - The Colorado River Commission represents the State of Nevada at all federal, interstate and international discussions regarding the management and operations of the Colorado River.

community well - each home on a community well is usually limited to 1,000 gallons per day.

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desalinization - the process of salt removal from sea or brackish water.

dilution - the process of adding a known amount of a solvent (usually water) to another solution to make it less concentrated.

distillation - the separation of different substances in a solution by boiling off those of low boiling points first. For example, water can be distilled and the steam condensed back into a liquid that is almost pure water. The impurities (minerals) remain in the concentrated residue.

domestic water use - extends to culinary and household purposes directly related to a single-family dwelling, including the watering of a family garden and lawn, and watering of livestock and other domestic animals or pets. The pumpage of a domestic well may not exceed a daily maximum of 1,800 gallons.

domestic well - a well that serves one home.

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."

drip irrigation - above ground, low-pressure watering system with flexible tubing that releases small, steady amounts of water through emitters placed near individual plants.

drought - generally, the term is applied to periods of less-than-average precipitation over a certain period of time; nature's failure to fulfill the water wants and needs of man.

effluent - water that flows from a wastewater treatment process.

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 be 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.

erosion - the wearing away of land surface by wind, water, ice or other geologic agents. This occurs naturally from weather or runoff but is often intensified by human land-use practices.

estuary - an area where fresh water meets salt water, such as with bays, mouths of rivers, salt marshes and lagoons.

evaporation - the process by which water becomes a vapor at a temperature below the boiling point.

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first in time, first in right - a common phrase indicating that older water rights have priority over more recent rights if there is not enough water to satisfy all rights.

forebay - a storage tank or small reservoir constructed specifically to establish a stable operating supply of water for the intake of a pumping station.

Geographic Information System (GIS) - a geographically referenced database that connects information about things to locations, which can be referenced by any convenient system such as latitude and longitude or three-dimensional coordinates.

Global Positioning System (GPS) - a system that establishes the location of a radio-based computer receiving signals from orbiting space satellites, possibly in combination with the use of a transmitter and a local base station.

greywater - untreated water after it has been used for showering, bathing, clothes washing, hand washing and faucet uses. Water contaminated by human or animal wastes or by chemicals is not considered greywater.

groundwater - the supply of water found beneath the Earth's surface in an aquifer that forms a natural reservoir.

groundwater law - the common law doctrine of prior appropriation as applied to groundwater.

groundwater recharge recovery - the withdrawal of banked groundwater recharge for use as a part of the water supply.

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hardness - the characteristic of water caused by calcium and magnesium that causes scaling, spots on glassware and other aesthetic concerns. Colorado River water in Lake Mead is considered to be very hard, having a calcium carbonate value of about  300 milligrams per liter.

hydroelectricity - electric energy produced by waterpower.

hydrogeology - the science dealing with the occurrence, distribution and movement of water below the surface of the Earth with a greater emphasis on geology.

infiltration - the gradual downward flow of water from the surface into soil material.

impermeable layer - a layer of solid material, such as rock or clay, which does not  allow water to pass through.

intake - the first point of entry for water flowing into a process or system. The Southern Nevada Water System's two primary water intakes are located at Saddle Island, more than 100 feet beneath the surface of Lake Mead.

intake system - the collection of integrated components that transmit water to the Southern Nevada Water System. The intake system may consist of an intake structure, tunnel, pumping equipment, metering equipment and piping.

lateral - a distinct branch of the transmission facility serving a particular turnout or small group of turnouts.

Las Vegas Valley - the topographic basin containing the City of Las Vegas, the City of North Las Vegas, the City of Henderson and certain unincorporated townships of Clark County.

Las Vegas Valley Water District (LVVWD) - a water purveyor that serves approximately 800,000 people in Southern Nevada, including the City of Las Vegas and other unincorporated areas within Clark County. LVVWD is a member of the Southern  Nevada Water Authority and the authorized operating agency for SNWA affairs and the Southern Nevada Water System.

Las Vegas Wash - the primary drainage channel for the Las Vegas Valley Hydrographic  Basin. Originating from a series of ephemeral creeks, desert washes and runoff  channels in the far northern and western parts of the hydrographic basin, the  wash takes shape in the eastern and southeastern metropolitan Las Vegas Valley, tracing a 12-mile-long curve that ends at Las Vegas Bay in Lake Mead.

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municipal water - municipal water may come from either groundwater or surface water  sources. Once water has entered a municipal water system, from any source, it  is considered municipal water.

natural recharge - the replenishment of a groundwater source from natural water  supplies such as precipitation and stream flows.

Nevada Department of Environmental Protection (NDEP) - the state agency responsible for overseeing air and water quality regulations and the primary agency for  enforcing compliance with the federal Clean Water Act and Clean Air Act.

Nevada Revised Statutes (NRS) - the law of the state as adopted and revised by the Nevada Legislature.

non-point source pollution - pollution that cannot be traced to a specific location.  Non-point source pollution occurs when rainwater, snowmelt or irrigation washes off parking lots, city streets, agriculture or urban landscape. As this runoff moves across the land surface, it picks up soil particles and pollutants, such as nutrients and pesticides.

non-revocable water right - a water right that's not subject to revocation if and when the water can be furnished by an entity such as a water district or municipality. Water right permits in the Las Vegas Valley with an initial priority date prior to March 24, 1955, are non-revocable.

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overdraft - that quantity of water pumped in excess of the available supply; the act of  overdrawing a water supply or aquifer in amounts greater than replenishment. Also, the sustained extraction of groundwater 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.

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.

place of use - the specific permitted location where water is to be applied or used. A water user cannot use water at another location without first transferring the water right or obtaining a new water right.

point of diversion - the point from which water is diverted from a source. A water user cannot divert water from another location without first transferring the water right or obtaining a new water right.

potable water - water suitable for drinking.

pumping station - a facility that pumps water to a higher elevation.

purveyor or purveyor member - with reference to public water supply systems, a municipality or other organization that sells and delivers water to customers. There are  seven purveyor members in the Southern Nevada Water Authority: The cities of Boulder City, Henderson, Las Vegas and North Las Vegas; Big Bend Water District; Clark County Sanitation District and the Las Vegas Valley Water District.

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receiving  reservoir - a water holding structure at the terminal end of a delivery system constructed and equipped to provide storage and release of water.

regulating tank - a tank constructed for the purpose of regulating system hydraulics  within an acceptable range over a particular reach of the transmission facilities.  A regulating tank absorbs pressure fluctuations and temporary mismatches between  downstream demands and upstream water supplies to maintain a balanced operation.

return flow credit - credits Nevada receives for treating wastewater and returning it to the Colorado River System.

revocable water right - a temporary water right that´s subject to revocation if and when water can be furnished by an entity such as a water district or municipality. Water right permits issued in the Las Vegas Valley with an initial priority date on or after March 24, 1955, are revocable.

riparian - areas adjacent to rivers and streams with plants adapted to moist growing  conditions found along waterways and shorelines. These areas are frequently important to wildlife habitat because of their greater density and succulence.

River Mountains Tunnels - two 3.9 mile tunnels that convey water from Lake Mead through the River Mountains to the Las Vegas Valley. One tunnel is 10 feet in diameter, constructed in 1971. The other tunnel is 12 feet in diameter and was constructed in 1997.

ROFC station - Rate-of-Flow Control Station. A facility constructed to control the rate at which water is delivered to a turnout.

Saddle Island - a small island on Lake Mead where two water intakes draw water from the lake for delivery to the water treatment facilities.

Southern Nevada Water Authority (SNWA) -  A seven member agency established in 1991 to address regional water issues in  Southern Nevada. The member agencies are the cities of Boulder City, Henderson,  Las Vegas and North Las Vegas; Big Bend Water District; Clark County Sanitation  District and Las Vegas Valley Water District.

Southern Nevada Water System (SNWS) - A system of water treatment and transmission facilities, including intakes, pumping stations, treatment facilities, rate-of-flow control stations, pipelines and aqueducts. The SNWS treats Colorado River water drawn from Lake Mead and sends it to the various water purveyors for distribution.

spillway - the channel or passageway around or over a dam used to divert excess water.

spring - a concentrated discharge of groundwater flowing out at the surface.

State Engineer - the head of the State of Nevada Division of Water Resources. The state engineer is responsible for granting rights to groundwater in the state of Nevada.

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total dissolved solids (TDS) - the dissolved inorganic (mineral) content of water. Lake Mead TDS varies from 550 to 750 mg/L, depending on changing lake levels.

transmission facility - transmits water from the treatment facility. The transmission system includes forebays, pumping equipment, regulating tanks, tunnels, piping, metering equipment and flow control equipment. For convenience in more specific reference, distinct branches of the transmission system may be identified and assigned unique names (see lateral).

treatment facility - the system that receives water from the intake system, processes the water to meet established water-quality standards and delivers it to the transmission facility.

tributary - a stream or other body of water, surface or underground, which contributes its water, even though intermittently and in small quantities, to another and larger stream or body.

turnout - the point of delivery of water from the Southern Nevada Water System transmission facility to a municipal water purveyor.

unaccounted water - water use that has not been metered or recorded. Unaccounted water is not necessarily lost or stolen water.

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water loss - water that leaks, evaporates or otherwise escapes from the water supply system before it can be put to use.

water quality - a term used to describe the chemical, physical and biological  characteristics of water with respect to its suitability for a particular use.

water resource - the quantity of water available in a certain time period from which a water supply may be developed. The Colorado River is the primary water resource for Southern Nevada's water supply. Other water resources available to Southern Nevada include groundwater, the Muddy River and the Virgin River.

water right - a legally-protected right granted by law to take possession of water, to divert the water and put it to beneficial use.

water supply - water available in a system for its intended use. Water diverted from the Colorado River and treated to drinking water standards becomes part  of the Southern Nevada Water System's water supply.

water table - the upper surface of a zone of saturation; the upper surface of  the groundwater.

watershed - the land area that drains water to a particular stream, river or lake. It's a land feature that can be identified by tracing a line along the highest elevations between two areas on a map, often a ridge.

well driller - individual who has the proper license, equipment and ability to drill a well.

wellhead protection area - the geographic boundaries of an area through which groundwater contaminants could reach a drinking water supply well within a specified period of time (usually 10 years).

wetlands - an area (including swamp, marsh, bog, prairie pothole or similar area) having a predominance of hydric soils that are inundated or saturated by surface or  groundwater.

xeriscape (pronounced "zeer-ih-scape") - a water-efficient landscape design that incorporates low-water use plants.

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