Watershed Glossary


Definition of Terms

Alluvial soil
Soil deposits resulting directly or indirectly from the sediment transport of streams, deposited in river beds, flood plains, and lakes.
An underground layer of porous, water-bearing rock, gravel, or sand.
Bottom-dwelling; describes organisms which reside in or on any substrate.
Benthic macroinvertebrate
Bottom-dwelling (benthic) animals without backbones (invertebrate) that are visible with the naked eye (macro).
The animal and plant life of a region.
Biocriteria monitoring
The use of organisms to assess or monitor environmental conditions.
The mechanical alteration of a stream which includes straightening or dredging of the existing channel, or creating a new channel to which the stream is diverted.
Concentrated animal feeding operation (CAFO)
Large livestock (ie.cattle, chickens, turkeys, or hogs) production facilities that are considered a point source pollution, larger operations are regulated by the MDNR. Most CAFOs confine animals in large enclosed buildings, or feedlots and store liquid waste in closed lagoons or pits, or store dry manure in sheds. In many cases manure, both wet and dry, is broadcast overland.
Confining rock layer
A geologic layer through which water cannot easily move.
Hard sedimentary rock composed of microcrystalline quartz, usually light in color, common in the Springfield Plateau in gravel deposits. Resistance to chemical decay enables it to survive rough treatment from streams and other erosive forces.
Cubic feet per second (cfs)
A measure of the amount of water (cubic feet) traveling past a known point for a given amount of time (one second), used to determine discharge.
Volume of water flowing in a given stream at a given place and within a given period of time, usually expressed as cubic feet per second.
Separated or disjoined populations of organisms. Populations are said to be disjunct when they are geographically isolated from their main range.
Dissolved oxygen
The concentration of oxygen dissolved in water, expressed in milligrams per liter or as percent.
A magnesium rich, carbonate, sedimentary rock consisting mainly (more than 50% by weight) of the mineral dolomite (CaMg(CO3)2).
In danger of becoming extinct.
Found only in, or limited to, a particular geographic region or locality.
Environmental Protection Agency (EPA)
A Federal organization, housed under the Executive branch, charged with protecting human health and safeguarding the natural environment — air, water, and land — upon which life depends.
The upper layer of water in a lake that is characterized by a temperature gradient of less than 1o Celcius per meter of depth.
The nutrient (nitrogen and phosphorus) enrichment of an aquatic ecosystem that promotes biological productivity.
Exterminated on a local basis, political or geographic portion of the range.
The animals of a specified region or time.
Fecal coliform
A type of bacterium occurring in the guts of mammals. The degree of its presence in a lake or stream is used as an index of contamination from human or livestock waste.
Flow duration curve
A graphic representation of the number of times given quantities of flow are equaled or exceeded during a certain period of record.
A natural subsurface soil horizon seemingly cemented when dry, but when moist showing moderate to weak brittleness, usually low in organic matter, and very slow to permeate water.
Gage stations
The site on a stream or lake where hydrologic data is collected.
Gradient plots
A graph representing the gradient of a specified reach of stream. Elevation is represented on the Y-axis and length of channel is represented on the X- axis.
Rapid and frequent fluctuations in flow resulting from power generation by a hydroelectric dam’s need to meet peak electrical demands.
Hydrologic unit (HUC)
A subdivision of watersheds, generally 40,000-50,000 acres or less, created by the USGS. Hydrologic units do not represent true subwatersheds.
The region of a body of water that extends from the thermocline to the bottom and is essentially removed from major surface influences during periods of thermal stratification.
Deep, well defined channel with narrow width to depth ration, and limited or no lateral movement. Often newly formed, and as a result of rapid down-cutting in the substrate
Intermittent stream
One that has intervals of flow interspersed with intervals of no flow. A stream that ceases to flow for a time.
Karst topography
An area of limestone formations marked by sinkholes, caves, springs, and underground streams.
Loamy soils deposited by wind, often quite erodible.
Low flow
The lowest discharge recorded over a specified period of time.
Missouri Department of Conservation (MDC)
Missouri agency charged with: protecting and managing the fish, forest, and wildlife resources of the state; serving the public and facilitating their participation in resource management activities; and providing opportunity for all citizens to use, enjoy, and learn about fish, forest, and wildlife resources.
Missouri Department of Natural Resources (MDNR)
Missouri agency charged with preserving and protecting the state’s natural, cultural, and energy resources and inspiring their enjoyment and responsible use for present and future generations.
Mean monthly flow
Arithmetic mean of the individual daily mean discharge of a stream for the given month.
Mean sea level (MSL)
A measure of the surface of the Earth, usually represented in feet above mean sea level. MSL for conservation pool at Pomme de Terre Lake is 839 ft. MSL and Truman Lake conservation pool is 706 ft. MSL.
Organisms that live in the open water areas (mid and upper) of water bodies and streams.
Non-point source
Source of pollution in which wastes are not released at a specific, identifiable point, but from numerous points that are spread out and difficult to identify and control, as compared to point sources.
National Pollution Discharge Elimination System (NPDES)
Permits required under The Federal Clean Water Act authorizing point source discharges into waters of the United States in an effort to protect public health and the nation’s waters.
Increased inputs, viewed as a pollutant, such as phosphorous or nitrogen, that fuel abnormally high organic growth in aquatic systems.
Optimal flow
Flow regime designed to maximize fishery potential.
Perennial streams
Streams fed continuously by a shallow water table an flowing year-round.
Numeric value that describes the intensity of the acid or basic (alkaline) conditions of a solution. The pH scale is from 0 to 14, with the neutral point at 7.0. Values lower than 7 indicate the presence of acids and greater than 7.0 the presence of alkalis (bases).
Point source
Source of pollution that involves discharge of wastes from an identifiable point, such as a smokestack or sewage treatment plant.
Recurrence interval
The inverse probability that a certain flow will occur. It represents a mean time interval based on the distribution of flows over a period of record. A 2-year recurrence interval means that the flow event is expected, on average, once every two years.
Unconsolidated and partially weathered mineral materials accumulated by disintegration of consolidated rock in place.
Pertaining to, situated, or dwelling on the margin of a river or other body of water.
Riparian corridor
The parcel of land that includes the channel and an adjoining strip of the floodplain, generally considered to be 100 feet on each side of the channel.
7-day Q10
Lowest 7-day flow that occurs an average of every ten years.
7-day Q2
Lowest 7-day flow that occurs an average of every two years.
The upper and most weathered portion of the soil profile.
Special Area Land Treatment project (SALT)
Small, state funded watershed programs overseen by MDNR and administered by local Soil and Water Conservation Districts. Salt projects are implemented in an attempt to slow or stop soil erosion.
Stream Habitat Annotation Device (SHAD)
Qualitative method of describing stream corridor and in-stream habitat using a set of selected parameters and descriptors.
Stream gradient
The change of a stream in vertical elevation per unit of horizontal distance.
Stream order
A hierarchical ordering of streams based on the degree of branching. A first order stream is an unbranched or unforked stream. Two first order streams flow together to make a second order stream; two second order streams combine to make a third order stream. Stream order is often determined from 7.5 minute topographic maps.
The mineral and/or organic material forming the bottom of a waterway or water body.
The plane or surface of maximum rate of decrease of temperature with respect to depth in a water body.
A species likely to become endangered within the foreseeable future if certain conditions continue to deteriorate.
United States Army Corps of Engineers (USCOE) and now (USACE)
Federal agency under control of the Army, responsible for certain regulation of water courses, some dams, wetlands, and flood control projects.
United States Geological Survey (USGS)
Federal agency charged with providing reliable information to: describe and understand the Earth; minimize loss of life and property from natural disasters; manage water, biological, energy, and mineral resources; and enhance and protect the quality of life.
The total land area that water runs over or under when draining to a stream, river, pond, or lake.
Waste water treatment facility (WWTF)
Facilities that store and process municipal sewage, before release. These facilities are under the regulation of the Missouri Department of Natural Resources