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EPA Handbook Glossary

acidity - a measure of the number of free hydrogen ions (H+) in a solution that can chemically react with other sub- stances. 

alkalinity - a measure of the negative ions that are available to react and neutralize free hydrogen ions. Some of the most common of these include hydroxide (OH-), sulfate (SO 4)' phosphate (PO 4)' bicarbonate (HCOI) and carbonate 
(CO 3) 

ambient - pertaining to the current environmental condition. 

assemblage - the set of related organisms that represent a portion of a biological community (e.g., benthic macroinverte- brates). 

benthic - pertaining to the bottom (bed) of a water body. 

biochemical oxygen demand (BOD) - the amount of oxygen consumed by microorganisms as they decompose organic materials in water. 

biological criteria - numerical values or narrative descriptions that depict the biological integrity of aquatic communities in that state. May be listed in state water quality standards. 

channel - the section of the stream that contains the main flow. 

channelization - the straightening of a stream; this often is a result of human activity. 

chemical constituents - chemical components that are part of a whole. 

cobble - medium-sized rocks (2-10 inches) that are found in a stream bed. 

community - the whole of the plant and animal population inhabiting a given area. 

culvert - man-made construction that diverts the natural flow of water. 

designated uses - state-established desirable uses that waters should support, such as fishing, swimming, and aquatic life. Listed in state water quality standards. 

dissolved oxygen (DO) - oxygen dissolved in water and available for living organisms to use for respiration. 

dredge - to remove sediments from the stream bed to deepen or widen the channel. 

ecoregion - geographic areas that are distinguished from others by ecological characteristics such as climate, soils, geology, and vegetation. 

emergent plants - plants rooted underwater, but with their tops extending above the water. 

headwaters - the origins of a stream. 

impairment - degradation. 

impoundment - a body of water contained by a barrier, such as a dam. 

inert - not chemically or physically active. kick-net - a fine mesh net used to collect organisms. 

land uses - activities that take place on the land, such as construction, farming, or tree clearing. 

macroinvertebrate - organisms that lack a backbone and can be seen with the naked eye. 

NPDES - National Pollutant Discharge Elimination System, a national program in which pollution dischargers such as factories and sewage treatment plants are given permits to discharge. These permits contain limits on the pollutants they are allowed to discharge. 

orthophosphate - inorganic phosphorus dissolved in water. 

outfall - the pipe through which urban storm drains,  industrial facilities, and wastewater treatment plants discharge their effluent (waste- water) into a water body. 

permeable - porous 

pH - a numerical measure of the hydrogen ion concentration used to indicate the alkalinity or acidity of a substance. Measured on a scale of 1.0 (acidic) to 14.0 (basic); 7.0 is neutral. 

phosphorus - a nutrient that is essential for plants and animals. 

photosynthesis - the chemical reaction in plants that utilizes light energy from the sun to convert water and carbon dioxide into simple sugars. This reaction is facilitated by chlorophyll. 

pool - deeper portion of a stream where water flows slower than in neighbor- ing, shallower portions. 

protocol - defined procedure. 

reagent - a substance or chemical used to indicate the presence of a chemical or to induce a chemical reaction to determine the chemical characteristics of a solution. 

riffle - shallow area in a stream where 
water flows swiftly over gravel and rock. 

riparian - of or pertaining to the banks of a body of water. 

riparian zone - the vegetative area on each bank of a body of water. 

riprap - rocks used on an embankment to protect against bank erosion. 

saturated - inundated; filled to the point of capacity or beyond. 

sheen - the glimmering effect that oil has on water as light is reflected more sharply off of the surface. 

submergent plants - plants that live and grow fully submerged under the water. 

substrate - refers to a surface. This includes the material comprising the stream bed or the surfaces which plants or animals may attach or live upon. 

taxonomic key - a quick reference guide used to identify organisms. They are available in varying degrees of complexity and detail. 

titration - the addition of small, precise quantities of a reagent to a sample until the sample reaches a certain endpoint. Reaching the endpoint is usually indicated by a color change. 

tolerance - the ability to withstand a particular condition - e.g. pollution tolerant indicates that ability to live in polluted waters. 

tributaries - a body of water that drains 
into another, typically larger, body of water. 

turbidity - murkiness or.cloudiness of water, indicating the presence of some suspended sediments, dissolved solids, natural or man-made chemicals, algae, etc. 

water quality criteria - maximum concentrations of pollutants that are acceptable, if those waters are to meet water quality standards. Listed in state water quality standards. 

water quality standards - written goals for state waters, established by each state and approved by EPA. 

watershed - the area of land drained by a particular river or stream system. 



State Water Resources Control Board Glossary of Terms 

Canopy cover: The terrestrial vegetation that projects over the stream. 

Cover: Anything that provides protection from predators or ameliorates adverse conditions of stream flow and/or seasonal changes in metabolic costs. May be instream cover, turbulence, and/or overhead cover, and may be for the purpose of escape, feeding, hiding, or resting. 

Deposition: The settlement or accumulation of material out of the water column and onto the streambed. Occurs when the energy of flowing water is unable to support the load of suspended sediment.  

Fish habitat: The aquatic environment and the immediately surrounding terrestrial environment that, combined, afford the necessary biological and physical support systems required by fish species during various life history stages.  

Flow: a) The movement of a stream of water and/or other mobile substances from place to place; b) The movement of water, and the moving water itself, c) The volume of water passing a given. point per unit of time. Synonym: Discharge. 

Glide/run: Section of a stream with a relatively high velocity and with little or no turbulence on the surface of the water. 

Instream cover: Areas of shelter in a stream channel that provide aquatic organisms protection from predators or competitors and/or a place in which to rest and conserve energy due to a reduction in the force of the current. 

Macroinvertebrate: Organisms that lack a backbone and can be seen with the naked eye. 

Pool: Deeper portion of a stream where water flows slower than in neighboring, shallower portions.

Reach: A section of stream possessing similar physical features such as gradient and confinement; usually the length of stream between two tributaries. 

Representative reach: A length of stream that represents a large section of the stream with respect to area, depth, discharge, and slope. 

Specific reach: A length of channel uniform with respect to selected habitat characteristics or elements (discharge, depth, area, slope, population of hydraulic units), fish species composition, water quality, and type and condition of bank cover. 

Riffle: Shallow area in a stream where water flows swiftly over gravel and rock. 

Sediment: Fragmental material that originates from weathering of rocks and decomposition of organic material that is transported by, suspended in, and eventually deposited by water or air, or is accumulated in beds by other natural phenomena. I 

Stream (includes creeks and rivers): A stream is a body of water that flows at least periodically or intermittently through a bed or channel having banks and supports fish or other aquatic life. This includes watercourses having a surface or subsurface flow that supports or has supported riparian vegetation. 

Types of streams: 

           Ephemeral: One that flows briefly only in a direct response to precipitation in the immediate locality and whose channel is at all times above the water table. Intermittent or seasonal: One in contact with the ground water table that flows only at certain times of the year as when the ground water table is high and/or when it receives water from springs or from some surface source such as melting snow in mountainous areas. It ceases to flow above the streambed when losses from evaporation or seepage exceed the available flow.

           Perennial: One that flows continuously throughout the year. Synonym: Permanent stream. 

           Stream bank: The portion of the channel cross section that restricts lateral movement of water at normal water levels. The bank often has a gradient steeper than 45 degrees and exhibits a distinct break in slope from the stream bottom. An obvious change in substrate may be a reliable delineation of the bank.  

Substrate: The mineral and/or organic material that forms the bed of the stream. 

Undercut bank: A bank that has had its base cut away by the water action along the man-made and natural overhangs in the stream. 

Watershed: A catchment area or basin. The total land area draining to any point in a stream, as measured on a map, aerial photo or other horizontal plane. 

Wetland: An area subjected to periodic inundation, usually with soil and vegetative characteristics that separate it from adjoining non-inundated areas. 


State Water Resources Control Board Fact Sheet

Algae: Excessive algal growth may be an indication of insufficient flow, high water temperatures, lack of riparian cover, excessive nutrients or other factors. The presence of some algae is important because it fon-ns the base for the food chain. An imbalance in the amount of algae can decrease water clarity and alter the color of the water. 

Foam: The presence of foam may be an indication of detergents, excessive nutrients or other unnatural inputs to the waterway. While foam may be an undesirable result of pollution, it sometimes can result from natural causes (for example, kelp and other natural organic matter whipped into a frothy foam due to wave action along a beach.) 

Turbidity: In a general sense, this is also referred to as a lack of transparency or clarity. It is most commonly associated with rainfall events but can also 
be associated with excessive algal growth (e.g., a red tide) or point source pollution. In addition to visual observations of turbidity, this parameter can also be measured by empirical procedures. 

Color: Color can be assessed for both flowing water (e.g. in streams) or in lakes, estuaries or bays. Poor color (e.g. brown or yellowish) can indicate turbidity caused by sediment, pollution, or excessive algae blooms. 

Oil: Most of the hydrocarbon molecules found in petroleum are lighter than water and therefore float at its surface. Even very small amounts of oil 
can cause large rainbow colored "sheens," which result from the fact that hydrocarbon molecules are repelled by water molecules. When weathered oil winds up on a shoreline, the lighter molecules evaporate or degrade, 
and the remaining tar is left behind. While petroleum is biodegradable, it is also toxic. 

Litter: Litter degrades the aesthetic quality of a water body, but is often detrimental to wildlife due to entanglement or even ingestion. Litter can also increase nutrient loading. 

Odor: Certain odors, such as chemical, petroleum, decay, fecal matter, and rotten egg" smells can indicate water quality problems.


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