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Definition of Terms

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Acid is any of a large class of substances the aqueous solutions of which are capable of turning litmus indicators red, of reacting with and dissolving certain metals to form salts, of reacting with bases or alkalis to form salts. Acidic is a tendency to form an acid.
Algae (pl), a collective term referring to several groups of simple tiny photosynthetic plants, mostly microscopic, lacking roots, stems and leaves. They can be found in a variety of habitats. Many species of algae exist as single cells, others form simple filaments or colonies, and others exist as more complex structures like the larger seaweeds
Algal bloom
Algal blooms are the profuse growth and reproduction of a particular species of alga that responds to certain conditions in a water body (e.g.,temperature, nutrient content, etc.); this is usually a result of increased nutrient content, often from excessive use of fertilizers and detergents
Any of various cold-blooded, smooth-skinned vertebrate organisms of the class Amphibia, such as a frog, that characteristically hatch as aquatic larvae that breathe by means of gills and that metamorphose to an adult form with air-breathing lungs.
Any of the group of segmented worms (earthworms, ragworms, leeches)
Annelids are characterized by a long, soft body and cylindrical or somewhat flattened cross-section.
A layer of porous rock or soil that both holds water and allows this water to percolate through. A geologic formation that is capable of providing a usable amount of water to a well or spring
Land suitable for the economic production of crops, usually involving regular cultivation


The solid rock that underlies all soil, sand, clay, gravel, and loose material on the earth's surface.
The bottom layer of a water body
Benthic macroinvertebrates
Bottom-dwellers without backbones that can be seen with the unaided eye, such as some bugs, mollusks, crabs.
Plants and animals living on the bottom of a water body
Biological availability
The amount that can be utilized by plants and animals.
Biotic adjustment
Bloom (see Algal bloom)
Describes the discoloration of the waters of ponds, lakes or sometimes slow-flowing rivers by the dense growth of free-floating algae or algae forming a scum on the surface
BOD (Biochemical Oxygen Demand)
The amount of oxygen used by microorganisms to break down organic matter; measures of BOD are used to estimate organic loads in water samples
Buffer zone
Established zone along a stream or river (riparian zone) or a margin of perennial grass or other erosion-resistant vegetation next to a water-body that filters pollutants and reduces erosion before the run-off enters the water.
Capable of floating or keeping things afloat.


Canopy cover
Branches from trees and shrubs that shield the ground and water from the sun
Capillary action
Movement of water from saturated soil toward an area of drier soil; it can refer to movement in any direction, but upward capillary movement is of most significance to the salinity problem
The green pigment in plants that enables them to use the energy of the sun for photosynthesis
A fine-grained, firm natural material, plastic when wet, that consists primarily of hydrated silicates of aluminum.
Coliform bacteria (see Fecal Coliform bacteria)
Aquatic invertebrates that process food particles smaller than 1 mm. Tend to be present in all stream types, but make up a greater part of the "bug" populations in the lower river reaches
A directly or indirectly interacting group (assemblage) of organisms occupying a particular habitat
Running together, flowing together or intermingling - as where a tributary joins a river
Coarse Particulate Organic Matter; food for "bugs" in streams


The scattered remains of something broken or destroyed.
The breakdown of organic materials by micro-organisms
Decomposing plant material. The decomposing plant material releases nutrients which support the growth of estuarine phytoplankton, which are food for sponges, mollusks, snails and some fish. Non-living organic matter, such as fallen leaves or dead algae.
Dissolved Oxygen held within water; this oxygen is available to aquatic organisms and is affected by facors such as temperature, nutrient and pollutant input, and decomposition within the water column.
Branch of river or stream that does not return to the main stream after leaving it


Areas that exist as bridges between two different types of habitat or environment.
El Nino
A long-term cyclic global weather event that changes the composition of Pacific Ocean conditions and adjacent continental weather patterns
Lasting for a brief time; short-lived; transitory.
The upper layer of water in a lake that is comprised of uniformly warmer water.
A biological film that converts the organic matter into food for larger organisms, such as stonefly larvae or larger crustaceans that feed within the hyporheic zone.
Estimating hours
When estimating hours spent at a site, whether you visit it once a year to evaluate your restoration activities or conduct monitoring measurements, it is important to consider the 'people hours'. A one hour site visit by 5 people would translate to 5 hours of spent at the site. Estimating weekly or monthly hours spent at a site can then be calculated to the length of time the site was actively visited. Some sites are monitored seasonally and others may be monitored throughout the year. If 3 people visited a site 2 hours (=6 hours per day) for 7 days a week (=42 hours per week) over an 8 week time period, then an estimated 336 hours per year were spent at the site.
A general wetland habitat type the is related to the estuary.
Productive, rich in dissolved nutrients, and sometimes resulting in a seasonal oxygen deficiency.
The change of liquid into a vapor
Plants absorb water and release it as vapor into the atmosphere during the process of photosynthesis.
The three groups of macroinvertebrates that are indicators that a stream is relatively healthy: Ephemeroptera [eh FEMER opt ura] (Mayflies), Plecoptera [ple COP tera] (Stoneflies) and Trichoptera [tri COP tera] (Caddisflies). Generally, the more EPT taxa, the better the water quality and the less challenging the environment.


Where tectonic plates meet with each other. When they grind against each other or dislocate laterally or vertically, an earthquake occurs.
Fecal Coliform bacteria
Bacteria found in the intestines of warm-blooded animals, that aid in the digestion process; used as indicators of fecal contamination in water-quality analyses.
Silt (fines) are easily suspended in the water column. The natural influx of fines into a stream system most often comes from streambank erosion. Fines are deposited in the slow moving water, which typically can be found in the pool structure and long the "inside" edge of a meandering streambank.
fine particulate matter. Food for "bugs" in streams.
Replacement of "old" water with new, as in a lake or estuary.
The act or process of breaking or being broken.


Geologic formation
Describes the building materials (i.e. rocks, etc.) and the types of materials (i.e. basalt, limestone) of the land.
A rate of inclination; ascending or descending part of slope.
Aquatic invertebrates that remove attached algae from rock or wood surfaces in the current of a stream.
Ground water
Water found in aquifers or underground streams in bedrock fractures and between the individual grains of sand and gravel deposits.


Only eats plants
Hortonian flow
Water running (flowing) over the land
Hydraulic head
The measure of the energy within the water and is often measured as the water's elevation above sea level.
The bottom layer of water in a lake that is comprised of uniformly cooler water.


Impervious surfaces
Surfaces, such as roads and parking lots, that do not absorb water. Lawns are considered impervious surfaces because during heavy rains, water runs off of them.
To permeate by passing through the pores of another substance such as soil.
Intertidal zone
The area above the mean (average) low tide mark and below the mean high tide mark.




Living or growing in lakes. A lacustrine wetland is permanently flooded or wet when the tide is in.
Similar to leak. Water slowly moves downward carrying and moving particles of dirt, minerals and other debris as it goes.
Of, pertaining to, or living in moving water.


Very, very small organisms that eat plant matter. Meiofauna are food for fish fry and amphibians.
The complex of physical and chemical processes involved in the maintenance of life.
The middle layer of water in a lake that marks the transition between the top and bottom layers, where temperature changes rapidly with depth.
There are many devices that will measure water quality. For the purposes of water quality data collection, a meter can be an instantaneous meter/probe, a continuous meter/probe, or a spectrophotometer which is used for measuring nitrates and phosphates.
Milligrams of gas per liter of water (dissolved oxygen is reported in units of mg/l); mg/l is equivalent to parts per million or "ppm."
One type or species of plant covering large areas. Many agriculture fields are monoculture, where only one type of plant is raised. A monoculture does not have the adaptabilty and resilience of a natural system and is not as sustainable.


Between acid and alkaline.
Non-point pollution
Pollution coming from many small, unidentifiable sources, usually pollution carried by runoff.
One of the young of any insect that undergoes imcomplete metamorphosis.


Capable of surviving in only one environment.
Lacking in plant nutrients and having an abundance of dissolved oxygen throughout.
Eats plants and other animals
Organic Loading
The excessive input of nutrients into a water system
The diffusion of fluid through a semipermeable membrane until there is an equal concentration of fluid on both sides of the membrane.
Oxygenated water
Water constantly supplied with oxygen. Water falls, for example, mix oxygen with water.


Packing density
The shape of the particles will make a difference in how water will move through them. For example, large round pebbles will leave a lot of open spaces whereas sand packs tightly into an area.
Wetlands, nontidal, dominated by shrubs and trees - small, shallow, permanent or intermittent pond
Uses a host animal to gets its nourishment
Particle geometry
The shape of the particle (i.e., round, square, etc.)
Agents that cause disease, especially microorganisms such as a bacterium or fungus.
The ease with which water can pass through a material.
A plant that lives longer than one year
The process by which chlorophyll-containing cells in green plants convert incident light to chemical energy and synthesize organic compounds from inorganic compounds, especially carbohydrates from carbon dioxide and water, with the simultaneous release of oxygen.
Minute, floating aquatic plants.
A substance, such as chlorophyll or hemoglobin, that produces a characteristic color in plant or animal tissue.
Point source pollution
Pollution caused by an identifiable source like a sewer discharge or the outfall from a factory.
Something that pollutes, especially a waste material that contaminates air, soil, or water.
The amount of empty space in a material which determines how much water it will hold: the more pores, the more water.
Water droplets or ice particles condensed from atmospheric water vapor and sufficiently massive to fall to the earth's sufrace, such as rain or snow.
Hunts other animals for food. Predators consume other animals. Some benthic macroinvertebrates are predators which capture, grasp, pierce and suck the juice out of their prey. Found in all stream habitat types.
Small appendages that look like legs, located in the thorax of an insect. Black flies and midges, and caddisflies have prolegs.
The inactive stage in the metamorphosis of many insects, following the larval stage and preceeding the adult form.



A depression in gravel dug by salmon to lay their eggs.
A force that tends to oppose or retard motion.
The metabolic process by which an organism assimilates oxygen and releases carbon dioxide and other products of oxidation.
A riffle is characterized by shallow water two inches to one foot deep, moderately swift moving water, and a rocky stream bottom consisting of gravel from 1/4 inch to 10 inches in size.
Riparian area
The vegetated area constituting a buffer zone between the edge of the waterbody and the beginning of land use.
River continuum concept
The pattern of physical change in a watershed and the biotic adjustments are called the "River Continuum Concept".
Wetlands. Usually in a channel where the water flows or moves, at least occasionally.
Root wads
Root wads are individual roots of a plant or group of plants that intermingle creating a fine mesh or wad.
Rain or irrigation that cannot be absorbed into the ground, so it washes into the nearest water body, carrying soil, minerals, debris and pollution.


"can hold no more." Every space between rock and soil particles is filled with water.
belonging to the family Salmonidae, which includes salmon, trout and whitefishes.
Aquatic invertebrates common in the middle reaches of a stream.
Sea water intrusion
A freshwater system that has been subjected to the effects of nearby saltwater source. This may by caused by a geologic event such as an earthquake or by human impacts such as over-explotation of a ground water source
Soil, sand and minerals which are washed from land into waters, usually during a rain, and settle on the bottom as new substitute.
Do not move; may be attached to an object to keep from moving.
A thin layer of cells surrounding an object.
Aquatic invertebrates that process leaves and particulates greater than 1 mm, breaking them into smaller pieces for the "collector bugs." Tend to inhabit headwater streams and other areas with lots of canopy cover.
Silt and clay
Types of soil
The amount that can be dissolved in water.
A liquid capable of dissolving another substance.
The material comprising the streambed or beach; the surfaces which plants or animals may attach or live on.
Surficial deposits
Gravel, soil, rock and other loose material that lie on top of the bedrock. In these deposits, the spaces between the large materials are filled with smaller particles. For example, the spaces between pebbles and large stones are filled with sand, and the spaces between the grains of sand are filled with clay. This leaves very few open spaces for ground water storage and makes it difficult for water to move through the pores.


Of, pertaining to, or situated near the tarsus of the foot.
Taxon (pl. taxa)
A particular taxonomic grouping, for example, a particular species, genus, family, order, class, phylum, or kingdom.
The orderly classification of organisms into appropriate categories (taxa) with application of suitable and correct names:
  • kingdom
    • phylum
      • class
        • order
          • family
            • genus (plural: genera)
              • species
Tectonic plates
In being analogous to an orange peel, these plates represents the fragmented layer of the earth's crust. These plates may collide, fold, or slide by one another. They may create subduction zones, mountain ranges, or fault lines.
Being harmful, destructive or deadly to organisms
The process by which water taken up by plants from the soil evaporates from tiny pores on the leaf surfaces.
Smaller body of water flowing into a larger one.
The nutrient status of water body. See eutrophic, mesotrophic, and oligotrophic.
The degree of cloudiness is mainly indicative of the amount of solids suspended in the water and, to a lesser extent, the color of the water; this is usually measured by some type of 'light penetration' test.
The state or quality of being turbulent.


The rate of travel.


Water cycle (also hydrologic cycle)
Movement of water from the atmosphere to the earth -precipitation-and back to the atmosphere through run-off, infiltration, percolation, storage, evaporation and precipitation.
The area of land that drains a river system, a lake, or a bay; the dividing line between watersheds is physically defined by mountains, crests of hills or a ridge of higher ground.
A transitional area where the soil or substrate is at least periodically saturated or covered with water. Only those plants and animals adapted to this unique habitat can survive in wetlands.




Floating, often microscopic aquatic animals.

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