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Water and Environment Glossary


Acre foot: The amount of water that would cover one acre at the depth of one foot (325,900 gallons).

Aquatic Insect: Insect species whose larval and juvenile forms inhabit streams or lakes.

Benthic: Bottom-dwelling. Aquatic organisms that live on or in the stream bed.

Carrying Capacity: The maximum number of organisms that a particular habitat can support over the long-term. Limited by food, shelter, spawning or nesting area, rearing cover, etc.

Coagulation: The addition of coagulant particles to water to aid in removing suspended particles in the drinking water process. 

Collector: Aquatic insect that feeds by gathering detritus, bacteria, etc.

Community: The plants and animals that interact in a habitat. 

Cover: Overhanging or instream structures such as tree roots, undercut streambanks, boulders, or gabions that offer protection from predators or shelter from strong currents.

Current: Sometimes refers to the swiftest part of a stream flow; otherwise refers to the velocity of the flow, measured in feet or meters/seconds (ft/s, m/s).

Decomposer: A type of stream organism, such as bacterium or fungus, that processes dead organic matter.

Detritivore: Animal that feeds primarily on detritus.

Detritus: Nutritious mixture of digested and partly digested organic matter, bacteria, fungi, feces, etc.

Discharge: The amount of water flowing past a given point on a stream. Measured in cubic feet (or cubic meters) per second (cfs;cm/s).

Dissolved Oxygen: Oxygen dissolved in water. The amount depends on temperature of the water, plant photosynthesis, plant and animal respiration, and physical aeration caused by tumbling. Measured in parts per million (mg/L).

Doctrine of Prior Appropriation: ÒFirst in Time, First in Right.Ó

Ecosystem: The interacting plants, animals, and physical components (sunlight, soil, air, water) of an area.

Effluent: Waste liquid flowing into a river or lake from a house, industry, sewage treatment plant, or other source.

Erosion: Detachment of soil particles by water, wind, ice, gravity or organisms.

Evapotranspiration: Collective term for evaporation and plant transpiration, which return water vapor from the earthÕs surface to the atmosphere.

Fecal Coliform Bacteria: Bacteria common to the intestinal tract of mammals. Indicates biowaste from livestock or humans and may be a sign of disease-causing pathogens.

Filtration: The filtering out of particles during the purification process for drinking water.

Food Web: A community of organisms that are dependent on one another for food.

Gradient: The slope of the streambed profile.

Groundwater: Water that sinks into the ground and collects over impermeable rock. It then flows laterally toward a stream, lake, or ocean. Wells tap it for our use. Its surface is called the Òwater tableÓ.

Habitat: The specific environment in which an organism lives and on which it depends for food and shelter.

Hardness: The concentration of calcium or magnesium in water; affects the availability of nutrients and toxic substances to stream organisms.

Headwaters: Small streams and creeks at the uppermost end of a river system.

Hydrologic Cycle (Water Cycle): Water in its various manifestations as vapor evaporated from oceans, lakes, streams, and plants; rain and snow; snowpack or glacier; groundwater or surface runoff; and finally as streams and rivers returning to the sea.

Larva (plural: larvae): Immature insect of the type that pupates into adult form.

Limiting Factor: A condition or situation that limits size of a population (e.g., spawning or rearing habitat, food, cover, migration barrier, disease, predation).

Macroinvertebrates: Bottom-dwelling insects found under rocks in creekbeds.

Meander: The tendency of moving water to form S-shaped curves (meanders).

Minimum Instream Flow: Water rights that are used to ensure enough water remains in the stream to support aquatic life.

Monitor: To track a characteristic, such as dissolved oxygen, nitrate level, or fish population, over a period of time using uniform methods to evaluate change.

Non-point Source: Diffuse, overland runoff containing pollutants. Includes runoff collected in storm drains.

Nymph: Immature form of insects such as stoneflies and mayflies that do not pupate.

Parameter: A variable quantity - such as temperature, dissolved oxygen, or fish population Ñ that is the subject of a survey of sampling routine.

Periphyton: Plants, usually algae, attached to rocks or other instream objects.

pH: Measure of acidity. Stands for Òthe negative logarithm of free hydrogen ionsÓ in water. Water of low pH is acidic; high pH is basic, or alkaline.

Point Source: A pipe that discharges effluent into a stream or other body of water.

Population: A discrete portion of a species that interbreeds. If isolated from other populations of the species for long periods of time, it may evolve into a separate race or species.

Predator: A carnivorous animal that preys on other animals.

Reach: A stream section with fairly homogenous characteristics.

Riffle: A shallow, gravelly area of streambed with swift current. Used for spawning by salmonids and other fishes. The most productive area of a stream.

Riparian Zone: The border of a stream or river above its banks; affects the stream and is affected by it.

Sediment: Fine soil or mineral particles.

Side Channel: A flood channel or abandoned stream channel connected to a stream or river at periods of high flow. Serves juvenile fish as rearing habitat and refuge from floods.

Siltation: The process of becoming clogged with fine sediments.

Storm Drain: A system of gutters, pipes, or ditches used to carry stormwater runoff into sewers or streams.

Stormwater Runoff: Surface water that washed off land after a rainstorm. In developed watersheds it flows off roofs and pavements into storm drains which may feed directly into the stream; often carries concentrated pollutants.

Suspended Sediments: Fine mineral or soil particles that remain suspended by the current until deposited in areas of weaker current. They create turbidity and, when deposited, can smother fish eggs or alevins. Can be measured in a laboratory as ÒTotal Suspected SolidsÓ (TSS).

Toxic: Poisonous, carcinogenic, or otherwise harmful to life.

Turbidity: A measure of material, usually fine sediments, suspended in water; determined by passing light through a water sample.

Urban Stream: A stream passing through urbanized area. Impacted by urban stormwater runoff; often channelized; sometimes trashed. Usually an excellent candidate for rehabilitation.

Watershed: The entire drainage area or basin feeding a stream or river. Includes surface water, groundwater, vegetation, and human structures.

Water Rights: Legally established right to appropriate water from a given stream.

Water Table: The upper surface of the groundwater; the level below which the soil is saturated with water. Its depth is influenced by rainfall and by human development (wells, drainage ditches, loss of wetlands, etc.).

Wetlands: Habitats flooded with shallow water all or part of the year. Can be identified by unique plants which have adapted to oxygen-deficient (anaerobic) soils. Wetlands influence stream flows and water quality.

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Last Page Update - Tuesday December 27, 2005