Acid Precipitation
All forms of precipitation that have an acidity lower than normal rainfall (pH 5.6).
Acre-Foot
The amount of water needed to cover one acre of surface area to the depth of one foot (12 inches).
Aggradation
The build-up of sediments at the headwaters of a lake or reservoir or at a point where streamflow slows to the point that it will drop part or all of its sediment load
Algae
Simple one-celled or many-celled plants, capable of photosynthesis; usually aquatic.
Algal Bloom
Rapid growth of algae on the surface of lakes, streams, or ponds; stimulated by nutrient enrichment.
Alluvium
Sand, clay, and other earth materials gradually deposited by streams along riverbeds and floodplains.
Analysis of Covariance
A statistical procedure that examines the relationship between two or more measures simultaneously (i.e., one dependent variable and one or more independent variables).
Anthropogenic
Relating to the scientific study of the origin of man; human.
Aquatic
Plants or animal life living in, growing in, or adapted to water.
Aquifer
Saturated geologic material sufficiently permeable to yield significant quantities of water to wells and springs; described as artesian (confined) or water table (unconfined).
Available Nutrient
That portion of any element or compound (such as phosphorus and nitrogen) in the soil that can be readily absorbed and assimilated by growing plants.
Bank Stabilization
Implementation of measures along a streambank to prevent or reduce bank erosion.
Bank Storage
The water which infiltrates the banks of a stream channel during high flows or floods, is stored there, and is released to the stream after the high water recedes.
Basin
A physiographic region bounded by a drainage divide; consists of a drainage system comprised of streams and often natural or man-made lakes. (Also called drainage basin or watershed.)
Best Management Practices (BMPs)
Methods, measures, or practices to prevent or reduce water pollution and to protect other environmental values.
Biochemical Oxygen Demand (B.O.D.)
The quantity of oxygen utilized in the biochemical oxidation of organic matter in a specified time and at a specified temperature. Waste discharges containing high levels of B.O.D. will deplete oxygen supplies in receiving waters..
Biological Availability
Refers to the form that a substance or compound can take that can be readily used for plant or animal growth. Depending on their chemical structure, certain compounds are more available for plant growth than others.
Buffer Strip
Strips of grass or other erosion-resistant vegetation between a waterway and an area of more intensive land use.
Chlorophyll a
The green molecule in plant cells that carries out photosynthesis. It is used as an indicator of plant and algae productivity and acts as an empirical link between nutrient concentrations and other biological phenomena in lakes. Higher values suggest deteriorating water quality.
Cubic Feet Per Second (cfs)
A unit expressing rate of discharge, typically used in measuring streamflow. One cubic foot per second is equal to the discharge in a stream of a cross section one foot wide and one foot deep, flowing with an average velocity of one foot per second; equals 448.8 gallons per minute.
Database
A collection of information kept in accessible form for purposes of research, comparison and analysis.
Dissolved Oxygen (DO)
The amount of free oxygen dissolved in water and readily available to aquatic organisms.
Easement
A legal instrument enabling the giving, selling, or taking of certain land or water rights without transfer of title, such as for the passage of utility lines.
Effluent
Liquid attributed to human waste, i.e. sewage arising from various uses of water; often refers to waste water from a sewage treatment or industrial plant.
Ephemeral Stream
A stream that flows only part time usually during snow melt periods or following rainstorms.
Erosion
The removal or wearing away of soil or rock by water, wind or other forces or processes. Erosion occurs naturally from weathering or runoff, but can be intensified by land clearing practices.
Eutrophication
The addition of nutrients to a body of water. Accelerated by human activities, abundant growth of aquatic plants may consume much of the dissolved oxygen, making the lake uninhabitable for the previous diversity of fish and other aquatic life.
Floodplain
Any normally dry land area that is susceptible to being inundated by water from any natural source. This area is usually lowland adjacent to a stream or lake.
Fluvial Deposits
Sediments deposited by river action.
Fresh Water
Water without salinity.
Groundwater
The supply of fresh water that forms a natural reservoir under the earth’s surface in soil and bedrock.
Groundwater Recharge
The natural renewal of ground water supplies by infiltration of rain or recharge other precipitation through the soil.
Hydrograph
A graph showing the changes in discharge of a stream or river, or the changes in water levels of a well with the passage of time.
Hydrology
The area of science dealing with the study of the waters of the earth and its atmosphere.
Hypolimnion
The lowermost, non-circulating layer of cold water in a thermally stratified lake; usually deficient of oxygen.
Instream Flows
The water left in a stream to maintain the existing aquatic resources and associated wildlife and riparian habitat.
Labile
Constantly undergoing or likely to undergo chemical change; unstable.
Leaching
The removal of nutrients, chemicals or contaminants from the soil by water movement through the soil.
Limnology
The area of science dealing with the study of freshwater aquatic ecology.
Mass Flux
The input or gain and output or loss of materials (such as nutrients) to an area such as a body of water.
Mass Wasting
A general term for a variety of processes by which large masses of earth material are moved by gravity either slowly or quickly from one place to another.
Mesotrophic
Descriptive of lakes in transition from oligotrophic status toward eutrophic. They are still generally pristine, but fish species are mixed, nutrient levels are higher and water is not quite as crystal clear.
Mitigation
An action designed to lessen or reduce adverse impacts; frequently used in the context of environmental assessment.
Nitrogen
A primary chemical element which is a part of all plant and animal tissues. It can promote algal blooms that cause eutrophication if it runs off or leaches out of the surface soil.
Nonpoint Source
A diffuse source of water pollution that does not discharge through a pipe.
Nutrients
Elements or compounds essential to life, including carbon, oxygen, nitrogen, phosphorus, and many others.
Nutrient Budget
The quantity of a given element or compound available for plant productivity over time. Changes in plant productivity are directly related to changes in the nutrient budget.
Nutrient Loading
Increases in the nutrient budget attributed to either increases from human-related or natural events.
Oligotrophic
Descriptive of crystal-clear lakes characterized by cold water fish species, low nutrient content and generally pristine features.
Ortho Phosphorus
The form of phosphorus most available to algae for growth.
Particulate Organic Carbon
Carbon content of particles in the water derived from living organisms (includes algae, waste products, dead or decayed organisms)
Permeability
The capacity of porous rock, sediment, or soil to transmit water.
pH
A measure that indicates the relative acidity or alkalinity of a substance. The pH scale ranges from 0 (most acid) to 14 (most basic), with a pH of 7 being neutral.
Phaeophytin
Formed when Chlorophyll adegrades. Data are used to correct for degradation of Chlorophyll athat might occur between sample collection and analysis.
Phosphorus
One of the primary nutrients required for the growth of aquatic plants and algae. Phosphorus is often the limiting nutrient for the growth of these plants. (See nitrogen.)
Point Source
Discrete sources of pollution, such as pipes, ditches, channels, wells, containers, or other vessels.
Pollution
Any contaminant or impurity.
Primary Productivity
The ability of a body of water to grow algae, measured as grams of carbon per square meter.
Recharge
The processes involved in the addition of water to the zone of saturation; also the amount of water added.
Revegetation
The planting of ground cover on highly erodible and marginal lands as a means of preventing further erosion.
Riparian
Located or living along or near a stream, river or body of water.
River Hydrograph
The pattern of a river or lake expressed as in-flow and out-flow ratios (such as cubic feet per second) and containing temperature, chemical and other expected characteristics.
Runoff
Water from rain, snow melt, or irrigation that flows over the ground surface and returns to streams. It can collect pollutants from air or land and carry them to the receiving waters.
Secchi Disk
A 20cm reflective disk used by volunteers and professional researchers to determine water clarity and derive a value used in computing a lake’s trophic status.
Sediment
Solid material (silt, sand, or organic matter) that has been moved from its site of origin and has settled to the bottom of a watercourse or water body. Excessive amounts can clog a watercourse. If disturbed, it can contribute to turbidity.
Sedimentation
The deposition of sediment from a state of suspension in water or air.
Solubility
The capacity to be dissolved or liquefied.
Suspended Solids
Solids floating in the water column that generally impart a cloudy appearance to water, sewage, or other liquids.
Terrestrial
Living or growing on land rather than in water or air.
Tertiary Waste
Selected biological, physical, and chemical separation processes to remove organic and treatment inorganic substances that resist conventional secondary treatment practices.
Total Maximum Daily Load (TMDL)
A U.S. Environmental Protection Agency determined level of pollution that can be permitted to enter a body of water if water quality is to be maintained.
Total suspended Solids (TSS)
Solids, found in waste water or in a stream, which can be removed by filtration. The origin of suspended matter may be man-made wastes or natural sources such as silt.
Tributary
A steam that contributes its water to another stream or body of water.
Trophic Status
The descriptive phase of a lake: oligotrophic, mesotrophic, eutrophic or somewhere in between. (Flathead Lake currently is described as oligomesotrophic).
Turbidity
Haziness or cloudiness in water because of suspended silt or organic matter.
Voluntary Nutrient Reduction Strategy (VNRS)
The voluntary strategy through which the Flathead Basin Commission will work with local groups and individuals to identify and implement the non-regulatory means to achieve the Total Maximum Daily Load (TMDL) for Flathead Lake.
Water Column
A cross section of a body of water from a point on the surface, straight down to the bottom.
Water Cycle
The continuous circulation of water in systems throughout the planet, involving condensation, precipitation, runoff, evaporation and transpiration.
Water Pollution
The presence of harmful material in water in sufficient quantities to result in a measurable degradation of the water quality.
Water Quality
A term used to describe the chemical, physical, and biological characteristics of water with respect to its suitability for a particular use.
Watershed
The area of land that drains into a particular watercourse or water body.
Wetlands
Any land area that tends to be regularly wet or flooded.
Zooplankton
Plankton that is composed of tiny animals and animal matter.
