AWRI Information Services Center

Lower Grand Watershed Interactive Tool (WIT) - General Watershed Terminology

FYI on Local Water Issues

A B C D E F G H  I  J K L M N O P Q R S T U V W X Y Z


Absorption - the process of taking up one substance into the body of another
Aerobic - living or active only in the presence of oxygen
Aggregate - mass or cluster of soil particles, often having a characteristic shape
Alkalinity - the capacity of water to neutralize acids
Anaerobic - living or active in the absence of oxygen
Antecedent Soil Condition - Soil moisture condition at the start of a storm event, influences runoff
Aquifer - a sand, gravel or rock formation capable of storing or conveying water below the surface of the land
Assimilative Capacity - natural ability of surface water to accept potential pollutants without harmful effects


Bacteria - microscopic plants, which occur as single cells, chains, filaments, well-oriented groups or amorphous masses
Bed Load - sediment particles resting on or near the channel bottom pushed or rolled along by the flow of water
Best Management Practice (BMP) - a conservation practice that is an effective, practical means of preventing or reducing pollution from nonpoint sources


Channel Flow - observable movement of surface water in a confined zone
Clay - soil particle less than 0.002 mm in diameter
Coliform Bacteria - a group of bacteria predominantly inhabiting the intestines of man or animal but also found in soil
Critical Area - area designated on a watershed map as contributing nonpoint source pollutants

Back to Top


Drainage - the removal of excess soil water from the soil profile


Effluent - the discharge of a pollutant, or pollutants, in a liquid form from a containing space
Erosion - detachment and movement of rocks and soil particles by gravity, wind and water
Eutrophication - natural or artificial process of nutrient enrichment whereby a water body becomes filled with aquatic plants and has a low oxygen content
Evapotranspiration - the loss of water from an area by evaporation from the soil and plant surfaces and by transpiration of plants


Fecal Coliform - the portion of the coliform group of bacteria originating in the intestinal tract of man and other warm-blooded animals
First Flush - phenomenon observed after prolonged dry spell in which concentration of pollutants in runoff is higher in earlier stages of a storm event
Fungicide - chemical used to destroy fungi


Grassed Waterway - a natural or constructed watercourse or outlet that is shaped or graded and established in suitable vegetation for the disposal of runoff
Groundwater - the subsurface water supply in the saturated zone below the water table

Back to Top


Half-Life - the time required for one-half of a specified substance to degrade
Herbicides - chemicals used to kill undesirable vegetation
Hydric Soils - a soil that is saturated, flooded, or ponded long enough during the growing season


Infiltration - the downward entry of water into the soil
Inorganic - materials not derived from hydrocarbons
Insecticides - chemicals used to kill insects


Leaching - the removal of salts and other materials from the soil by water movement through the soil profile
Loading - the quantity of a substance entering the receiving waters


Managerial Controls - control measures which involve changes in timing, chemical application rates, or tillage systems for the purpose of reducing the loss of pollutants
Mineralization - the microbial conversion of an element from an organic to an inorganic state
Mulch - any substance which is spread or allowed to remain on the soil surface to decrease the effects of raindrop impact and runoff

Back to Top


Nonpoint Source - entry of effluent into a water body in a diffuse manner with no definite point of entry and where the source is not readily discernible<


Organic Matter - residue of plant or animal origin


Particulate Matter - any solid so finely divided as to be capable of being wind-blown or suspended in air or gas
Pathogens - disease causing organisms
Percolation - the downward movement of water through the soil
Pesticide - a chemical used to kill or control pest such as weeds, insects, algae and other undesirable agents
Phosphorus - a nonmetallic element that occurs widely and is essential to growth of aquatic organism as well as all forms of life
Point Source - the release of an effluent from a pipe or discrete conveyance into a water body or a watercourse leading to a body of water
Pollutant - any substance of such character and in such quantities that when it reaches a body of water, soil, or air it is degrading in effect so as to impair its usefulness or render it offensive

Back to Top


Resource Management System - a combination of best management practices that, when installed, will at a minimum protect the resource bas by meeting acceptable soil losses, protect or improve water quality, and conserve plant, air and animal resources
Riparian Area - area bordering streams, lakes, rivers and other water courses
Runoff - that portion of the precipitation or irrigation water which leaves the field over the surface and appears in the surface streams or water bodies


Sand - soil particles between 0.05 and 2 mm in diameter
Sediment - the solid material, both organic and inorganic, that is in suspension, is being transported, or has been moved from its site of origin to rest on the earth's surface
Sheet Flow - water, usually storm runoff, flowing in a thin, even layer over relatively wide ground surface and not concentrated in channels
Silt - soil particles between .05 and .002 mm in diameter
Structural Controls - erosion control measures which require a capital investment and construction activities installed
Suspended Loads - sediment particles maintained in the water column by turbulence and carried with the flow of water

Back to Top


Tail Water - the runoff of irrigation water from the lower end of an irrigation field
Terrace - an earth embankment, channel or a combination ridge and channel constructed across the slope to decrease the slope length and control runoff
Total Dissolved Solids (TDS) - all material that passes through the standard glass fiber filter (0.45 um pore size)
Total Suspended Solids (TSS) - a measure of the amount of suspended solids found in the water column
Toxicity - the degree to which a chemical detrimentally affects an organism


Vegetative Controls - control measures or practices which usually involve the use of cropping systems, permanent grass, or other vegetative cover to reduce erosion and control pollutants
Volatilization - the loss of a substance through evaporation or sublimation


Water Quality - the biological, chemical, and physical conditions of a water body; a measure of a water body's ability to support life
Watershed - the geographic region within which water drains into a particular river, stream, or body of water. A watershed includes hills, lowlands and the body of water into which the land drains. Watershed boundaries are defined by the ridges separating watersheds.
Water Table - the upper level of a saturated zone below the soil surface

Back to Top

Back to Local Water Issues

Source: Michigan Department of Environmental Quality

Page last modified January 19, 2011