Water Glossary

A

• acre-foot: Approximately 326,000 gallons; roughly equal to the amount of water a family of four uses in and around the home in a two-year period; the amount of water it would take to cover an acre of land one foot deep.
• allotment: a share or portion.
• aqueduct: a structure used to transport water from remote areas to large urban centers.
• aquifer: an underground space where water collects.
• artesian aquifer: a confined aquifer where water is contained under great pressure between two impermeable layers.

B

• bacteria: a single-celled microscopic organism.
• bog: a wetland covered by a shallow layer of water, or no visible water at all, and containing ground that is made of sphagnum moss.
• bottom life: animals that live on the bottom of a healthy body of water.
• brackish water: Refers to water with a mineral content in the general range between freshwater and seawater.
• brine: the by-product of desalinating water, about twice the salinity of seawater.

C

• California Aqueduct: a 444-mile structure that transports water from the San Francisco/San Joaquin Delta to Southern California.
• Clean Water Act of 1972: a law that requires the federal government to regulate the quality of the nation’s water supply.
• Colorado River Aqueduct: a 242-mile structure that transports water from the Colorado River to Southern California.
• Comprehensive Environmental Response, Compensation and Liability Act of 1980 (Superfund): a law enacted by the federal government to clean up hazardous waste sites that threaten groundwater resources.
• condensation: water vapor or gas forming a cloud prior to becoming a liquid again.
• confined aquifer: an aquifer found between two impermeable layers.
• conservation: saving water and other natural resources.

D

• dam: a structure used to hold back the flow of water.
• desalination: a process that removes dissolved salts from salty or brackish water.
• dike: a structure used to confine or control water.
• disinfection: a process in which chlorine and other chemicals are added to water to kill harmful microorganisms.
• diversion canal: a structure used to change the directional flow of water.

E

• entrainment: the incorporation of all life stages of fish and shellfish with intake water flow entering and passing through a cooling-water intake structure and into a cooling-water system.
• estuary: an area where a river empties into an ocean or sea.
• evaporation: water turned into a vapor or gas and rising into the atmosphere.

F

• filtration: a process that separates small particles from water by using a porous barrier to trap the particles and allowing the water through.
• fish: a vertebrate (animal with a spine) that lives in water.
• flocculation: a process in which a chemical such as alum or ferric chloride is added to water to cause dirt and other small particles to join together into “floc” or large clumps.

G

• groundwater: water that is stored in aquifers. Aquifers are replenished naturally with rainfall or snowpack or artificially through recharge basins with imported or recycled water.

H

• hydrologic cycle: a three-step process by which Earth is continuously able to recycle its water.

I

• impingement: the entrapment of all life stages of fish and shellfish on the outer part of an intake structure or against a screening device during periods of intake water withdrawal.
• imported water: water transported to our region from Northern California or the Colorado River Aqueduct.

L

• levee: a raised structure used to contain water and prevent flooding.
• Los Angeles Aqueduct: a 335-mile structure that transports water from the eastern Sierra Nevada to the City of Los Angeles.

M

• mangrove swamp: tropical and subtropical saltwater swamp that contains a species of saltwater tolerant tree or shrub.
• marsh: a wetland that is wet throughout the year and found at the edge of a river, lake or pond.
• micro-filtration: a membrane filtration process in which water passes through small pores of the micro-filtration membrane, accumulating particles on its surface. Periodically, flow is reversed to remove the debris. In ocean-water desalination, it is designed to remove particulate matter from seawater to allow the downstream reverse osmosis desalination process to efficiently remove dissolved salts.

N

• non-potable water: water not suitable for drinking. Can be used for landscaping, irrigation and industrial uses.
• non-point pollution source: pollution that comes from various sources not easily identified.

O

• Ogalla Aquifer: the largest aquifer in the United States, located in the Midwest.
• organism: a living plant or animal.
• oxygen: a gas upon which most life depends.

P

• potable water: water that is suitable for drinking.
• peak flow: highest flow level of a body of water.
• permeability: a measurement of how freely water moves between pieces of soil and rock.
• phytoplankton: microscopic free-floating green plants.
• point pollution source: pollution that comes from an easily identified source.
• porosity: a measurement of the amount of water held between pieces of soil and rock.
• Porter-Cologne Water Quality Act: a California law that gives the State Water Resources Control Board ultimate authority over water rights and water control policy.
• precipitation: water falling to Earth as rain, sleet, snow or hail.
• pretreatment: a process in wastewater treatment where metal screens are used to remove large objects and chunks of debris.
• primary treatment: the first process in wastewater treatment where solid matter is removed.

R

• recycled water: domestic wastewater purified through primary, secondary and tertiary treatment. Recycled water is ideal for most non-drinking water purposes such as landscaping, irrigation and industrial uses.
• reservoir: a man-made storage facility used to hold water until it is needed.
• reverse osmosis: a filtration process that forces water through membranes that contain microscopic holes, removing microorganisms, organic chemicals and inorganic chemicals, producing very pure water.

S

• Safe Drinking Water Act of 1974: a law enacted by the federal government that regulates the nation’s drinking water.
• saltwater marsh: a wetland that is wet throughout the year and found at the edge of a saltwater body.
• secondary treatment: the second process in wastewater treatment where microorganisms are used to digest organic particles.
• sediment: mud, sand or gravel that has settled to the bottom of a body of water.
• sedimentation: a process in which gravity causes small particles to settle to the bottom of a tank or basin.
• semi-arid: a mostly dry region that gets a small amount of precipitation.
• Superfund: see Comprehensive Environmental Response, Compensation and Liability Act.
• surface water: a body of water easily seen as it flows downhill to where it collects.
• swamp: a wetland that can alternate between being wet and dry for periods of time throughout the year.

T

• tertiary treatment: the third process in wastewater treatment where remaining small particles are filtered out of the water before disinfection.
• Title 22: a section of the California Code of Regulations pertaining to various aspects of drinking water and recycled water standards.
• turbidity: cloudy or muddy looking water caused by suspended or stirred up particles in the water.

U

• Ultra-Low-Flush Toilet: often referred to as ULFTs, these fixtures require only 1.6 gallons of water per flush. These conservation devices save a typical household 7,900 to 21,700 gallons of water each year.
• unconfined aquifer: an aquifer found close to Earth’s surface that allows water to seep into it.

W

• water conservation: the best tool for stretching water supplies without making unnecessary investments in infrastructure, shifting available water resources or negatively impacting the environment.
• watershed: an area of land where water drains from the higher elevation points into a larger body of water or into the soil.
• water table: the top surface of a body of groundwater.
• well: a hole dug into the ground that begins at the surface and ends where it reaches the water.
• West Coast Basin Aquifer: an aquifer that underlies the Southern California communities of West Basin Municipal Water District within its territories.
• wetland: an area of land that is wet for a period of time during the year.

Z

• zooplankton: microscopic free-floating animals.

*For additional definitions, please visit the California Department of Water Resources.