Glossary S-Z

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

salt water—water that has a high level of dissolved salts (oceans, seas).

saturated zone—a portion of the soil where all pores are filled with water. Aquifers are located in this zone. There may be multiple saturation zones at different soil depths separated by layers if clay or rock.

secondary treatment—a type of wastewater treatment process used to convert dissolved and suspended pollutants into a form that can be removed; a minimum level of treatment for municipal wastewater as required by the Clean Water Act.

sedimentation—a process that occurs when gravity pulls the clumps of sediment to the bottom.

sludge—any solid, semisolid or liquid waste that settles to the bottom of sedimentation tanks or septic tanks.

soft water—water that is relatively free of those minerals that cause soap to precipitate causing scale buildup.

solvent—a substance that dissolves another to form a solution.

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 water from Lake Mead and sends it to the various water purveyors for distribution.

specific heat—the number of calories needed to raise the temperature of one gram of a given substance 1degree C, compared to the number of calories (one) needed to raise the temperature of one gram of water 1 degree C.

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 for Water Resources. The state engineer is responsible for granting rights to surface water and groundwater in the state of Nevada.

storage tanks—water tanks that are used for storage and which come in several shapes and sizes: elevated, ground and standpipe.

stream—a body of flowing fresh water.

succession—gradual, orderly process of changes in a lake ecosystem brought about by changes in species types and populations; occurs over long periods of geologic time and ultimately results in the lake reverting back to land.

surface tension—a property of liquids in which the exposed surface tends to contract to the smallest possible area. It is caused by unequal molecular cohesive forces near the surface.

surface water—precipitation that does not soak into the ground or return to the atmosphere by evaporation or transpiration. It is stored in streams, lakes, rivers, ponds, wetlands, oceans and reservoirs.

survive—to remain alive or in existence.

suspended solids—small particles of solid materials in water that cause cloudiness or turbidity.

system—an orderly, interconnected arrangement of parts.

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tap water—water from a faucet (generally treated by a municipal water system and piped to homes and businesses).

temperature—the degree of heat or cold.

tertiary treatment—any level of treatment of wastewater beyond secondary treatment, which can include filtration, nutrient removal (usually N or P) and the removal of toxic chemicals or metals. Sometimes referred to as "advanced treatment."

thermometer—an instrument used to measure temperature.

total dissolved solids (TDS)—the inorganic or mineral content of water. Lake Mead TDS varies from 550 to 750 millions gallons per liter, depending on changing lake levels. A laboratory measurement of the quantity of solids present in wastewater that is one of the main indicators of the quality of pollutants present.

toxic—harmful to living organisms.

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).

transpiration—process in which water that is absorbed by the roots of plants moves up through the plant, passes through pores in the leaves and then evaporates into the atmosphere as water vapor.

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.

trough—a long open receptacle.

turbidity—the cloudy or muddy appearance of natural water caused by the suspension of particulate matter.

turbine—an engine run by the reaction, impulse or both of a current (such as a water current).

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.

unconfined aquifer—an aquifer containing groundwater that is not pressurized, having an impermeable layer below but not above it.

underground storage tank—any tank, including underground pipes connected to a tank, that has at least 10 percent of its volume underground and usually contains petroleum products or hazardous substances.

universal solvent—water; a material that can dissolve almost any other substance.

unpotable water—not suitable to drink.

vapor—a substance in a gaseous state.

variable—factor that may cause the results of an experiment or investigation to change (a controlled variable must remain constant throughout an experiment).

viscosity—the state or quality of having a cohesive and sticky fluid consistency; a measure of resistance to flow.

waterborne diseases—diseases spread by contaminated water.

water cooler—a free-standing container of water available for drinking.

water consumption—the quantity of water permanently removed over a given time period from a water source. (With respect to Nevada's use of the Colorado River, a quantity of water equal to water diversions after return flow credits are accumulated.) Nevada is presently allocated a consumption limit of 300,000 acre-feet per year from the Colorado River.

water cycle—continuous movement of water from the oceans and fresh water sources to the air and land and then back to the oceans.

water diversions—with respect to Nevada's use of the Colorado River, the quantity of water removed from the river over a certain time period. Water diversions from the Colorado River allowed by the U.S. Government are defined in various contract documents.

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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.

watershed—land area from which water drains to a particular surface water body.

water source—the place or thing from which water begins or arises.

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 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.

weather—conditions of heat, cold, wetness, dryness, clearness, cloudiness, etc.

well—a bored, drilled or driven shaft or dug hole. Wells range from a few feet to more than 6 miles in depth, but most water wells are between 100 and 2,000 feet in depth.

wellhead—the physical structure or device at the land surface from or through which groundwater flows or is pumped.

wetlands—areas that periodically have waterlogged soils or are covered with a shallow layer of water. Wetland areas typically support plant life that are adapted to life in wet environments.

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

zone of saturation—that region below the surface in which all voids are filled with liquid.

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