Alkalinity is a measure of the proton-accepting capacity of a solution. This property is also referred to as its "acid-neutralizing capacity", and is equal to the sum concentration of all proton acceptors in the solution or the total strong base concentration. Total alkalinity is operationally defined as the alkalinity neutralized by titration with a strong acid to the carbonic acid equivalence point. (IT = incremental titration, DIS = dissolved, TOT = total)
Basic fixed siteSite on streams at which streamflow is measured and samples are collected to assess the broadscale spatial and temporal character and transport of inorganic constituents of streamwater in relation to hydrologic conditions and enviromental settings. Reach assessments of ecological conditions and bed-sediment and tissue sampling also are conducted at these sites. NAWQA study units usually have 8-12 basic fixed sites.
Bed-sediment study is the assessment of concentrations and distributions of trace elements and hydrophobic organic contaminants in streambed sediment to assess spatial distribution.
Benthic Invertebrates are animals without backbones that live in association with streams and lake bottom habitats. Examples are larval insects such as caddisflies and mayflies, and crustaceans such as crayfish.
Comparison sites are similiar to indicator sites in that they represent a dominant land use within a basin, but are sampled less frequently.
Constituent code-- see Parameter code
Cubic foot per second (ft3/s, or CFS) is the rate of discharge representing a volume of 1 cubic foot passing a given point during 1 second and is equivalent to approximately 7.48 gallons per second or 448.8 gallons per minute or 0.02832 cubic meters per second.
Discharge is the volume of water (or more broadly, volume of fluid plus suspended sediment) that passes a given point within a given period of time.
Mean discharge (MEAN) is the arithmetic mean of individual daily mean discharges during a specific period.
Instantaneous discharge is the discharge at a particular instant of time.
Dissolved is that material in a water sample which passes through a 0.45 mm membrane filter. This is a convenient operational definition used by Federal agencies that collect water data. Determinations of "dissolved" constituents are made on subsamples of the filtrate.
Dissolved-solids concentration of water is determined either analytically by the "residue-on-evaporation" method, or mathematically by totaling the concentrations of individual constituents reported in a comprehensive chemical analysis. During the analytical determination of dissolved solids, the bicarbonate (generally a major dissolved component of water) is converted to carbonate. Therefore, in the mathematical calculation of dissolved-solids concentration, the bicarbonate value, in milligrams per liter, is multiplied by 0.492 to reflect the change.
Drainage area of a stream at a specific location is that area, measured in a horizontal plane, enclosed by a topographic divide from which direct surface runoff from precipitation normally drains by gravity into the river from an upstream specified point. Figures of drainage area given herein include all closed basins, or noncontributing areas, within the area unless otherwise noted.
Drainage basin is a part of the surface of the earth that is occupied by a drainage system, which consists of a surface stream or a body of impounded surface water together with all tributary surface streams and bodies of impounded surface water.
Flow System Study is a study conducted to characterize the spatial and temporal distribution of water quality in relation to ground-water flow and to increase understanding of the natural processes and human influences on ground water along a flowpath.
Gaging station is a particular site on a stream, canal, lake, or reservoir where systematic observations of hydrologic data are obtained.
GCMS (Gas chromatography mass spectrometry) is an analytical method used to measure chromatographic separation, identification, and quantification of pesticides isolated in natural-water samples.
HPLC (High-performance liquid chromatography) is an analytical method used for the chromatographic separation, identification, and quantification of pesticides isolated in natural-water samples.
Indicator site Stream sampling sites located at or near outlets of drainage basins with near homogeneous land use and physiographic conditions.
Integrator site Stream sampling sites located in drainage basins that are large and complex and often contain multiple environmental settings.
Intensive fixed sites Basic fixed sites with increased sampling frequency, during selected seasonal periods and analysis of pesticides for a period of about one year.
Ground-Water Land-Use studies are investigations of the concentrations and distribution of water-quality constituents in recently recharged ground water, associated with a near homogeneous land use and hydrogeologic conditions.
MRL (Minimum Reporting Level) is a statiscally determined level at which a particular substance can be measured with an acceptable level of confidence.
Micrograms per gram (uG/G, ug/g) is a unit expressing the concentration of a chemical element as the mass (micrograms) of the element sorbed per unit mass (gram) of sediment.
Micrograms per liter (uG/L, ug/L) is a unit expressing the concentration of chemical constituents in solution as mass (micrograms) of solute per unit volume (liter) of solution. One thousand micrograms per liter is equivalent to one milligram per liter.
Milligrams per liter (MG/L, mg/L) is a unit for expressing the concentration of chemical constituents in solution. Milligrams per liter represent the mass of solute per unit volume (liter) of solution. Concentration of suspended sediment also is expressed in mg/L, and is based on the mass of dry sediment per liter of water-sediment mixture.
National Stream-Quality Accounting Network (NASQAN) is a nationwide data-collection network designed by the U.S. Geological Survey to meet many of the information needs of government agencies and other groups involved in national or regional water-quality planning and management.
National Water-Quality Assesment (NAWQA) Program is a long-term program of the U.S. Geological Survey with goals to describe the status and trends of water-quality conditions for a large, diverse, and geographically distributed part of the Nation's ground- and surface-water resources, and to identify, describe, and explain the major natural and human factors that affect these observed conditions and trends.
Parameter Code is a 5-digit number used in the U.S. Geological Survey computerized data system, WATSTORE, to uniquely identify a specific variable. The codes used in WATSTORE are mostly the same as those used in the U.S. Environment Protection Agency data system, STORET. The Environmental Protection Agency assigns and approves all requests for new codes. For the NAWQA data report, Parameter codes are refered to as Constituents
Particle-size is the diameter, in millimeters (mm), of suspended sediment or bed material determined by either sieve or sedimentation methods. Sedimentation methods (pipet, bottom-withdrawal tube, visual- accumulation tube) determine fall diameter of particles in either distilled water (chemically dispersed) or in native water (the river water at the time and point of sampling).
Pesticides are chemical compounds used to control undesirable plants and animals. Major categories of pesticides include insecticides, miticides, fungicides, herbicides, and rodenticides.
Picocurie (PC, pCi) is one trillionth (1 x 10-12) of the amount of radioactivity represented by a curie (Ci). A curie is the amount of radioactivity that yields 3.7 x 10-10 radioactive disintegrations per second (dps). A picocurie yields 2.22 disintegrations per minute (dpm).
Reference site is a site located downstream (surface-water) or within (ground-water) a relatively undistrubed drainage basin that represent background conditions, but not neccessarily natural conditions, because most areas have been disturbed to some degree and atmospheric sources of contaminants do not respect basin boundaries.
Runoff in inches (IN, in) shows the depth to which the drainage area would be covered if all the runoff for a given time period were uniformly distributed on it.
Specific conductance is a measure of the ability of a water solution to conduct an electrical current. It is expressed in microsiemens per centimeter (us/cm) at 25C. Specific conductance is related to the type and concentration of ions in solution and can be used for approximating the dissolved-solids content of the water. Commonly, the concentration of dissolved solids (in milligrams per liter) is about 65 percent of the specific conductance (in microsiemens). This relation is not constant from stream to stream, and it may vary in the same stream with changes in the composition of the water.
Standard Length When measuring fish, standard length is the length from the tip of the upper jaw to posterior end of the fleshy peduncle.
Streamflow is the discharge that occurs in a natural channel. Although the term "discharge" can be applied to the flow of a canal, the word "streamflow" uniquely describes the discharge in a surface stream course. The term "streamflow" is more general than "runoff" as streamflow may be applied to discharge whether or not it is affected by diversion or regulation.
Study Unit is a major hydrologic system of the United States in which NAWQA studies are focused.
Study-Unit Survey is a broad assessment of the water-quality conditions of the major aquifer systems of the study unit.
Suspended (as used in tables of chemical analyses) refers to the amount (concentration) of undissolved material in a water-sediment mixture. It is associated with the material retained on 0.45- micrometer filter.
Suspended sediment is the sediment that, at any given time, is maintained in suspension by the upward components of turbulent currents or that exists in suspension as a colloid.
Suspended-sediment concentration is the velocity-weighted concentration of suspended sediment in the sampled zone (from the water surface to a point approximately 0.3 ft above the bed) expressed as milligrams of dry sediment per liter of water-sediment mixture (mg/L).
Suspended-sediment discharge (tons/day) is the rate at which dry weight of sediment passes a section of a stream or is the quantity of sediment, as measured by dry weight or volume, that passes a section in a given time. It is calculated in units of tons per day as follows: concentration (mg/L) x discharge (cfs) x 0.0027.
Synoptic sites are sites sampled during a short term investigation of specific water-quality conditions during selected seasonal or hydrologic conditions to provide improved spatial resolution for critical water-quality conditions.
Taxonomy is the division of biology concerned with the classification and naming of organisms. The classification of organisms is based upon a hierarchial scheme beginning with Kingdom and ending with Species at the base. The higher the classification level, the fewer features the organisms have in common. For example, the taxomy of a particular mayfly, Hexagenia limbata, is the following:
| Kingdom | -->> | Animalia |
| Phylum | -->> | Arthropoda |
| Class | -->> | Insecta |
| Order | -->> | Ephemeroptera |
| Family | -->> | Ephemeridae |
| Genus | -->> | Hexagenia |
| Species | -->> | Hexagenia limbat |
Taxonomic Code
Tissue study is the assessment of concentrations and distributions of trace elements and hydrophobic organic contaminants in tissues of aquatic organisms.
Total is the total amount of a given constituent in a representative water-suspended sediment sample, regardless of the constituent's physical or chemical form. This term is used only when the analytical procedure assures measurement of at least 95 percent of the constituent present in both the dissolved and suspended phases of the sample. A knowledge of the expected form of the constituent in the sample, as well as the analytical methodology used, is required to judge when the results should be reported as "total." (Note that the word "total" indicates that the sample consists of a water-suspended sediment mixture and that the analytical method determines all of the constituent in the sample.)
Total Length When measuring fish, total length is the distance to from the mouth to the tip of the caudal fin, when the mouth is closed and the lobes of the caudal fin are squeezed together.
Turbidity is a cloudy condition in water due to suspended sediment or organic matter, and is expressed as nephelometric turbidity units (NTU).
Water-column study are investigations of physical and chemical characteristics of stream water, which include suspended sediment, dissolved solids, major ions and metals, nitrients, organnic carbon, and dissolved pesticides, in relation to hydrologic conditions, sources, and transport.
Water year is the 12-month period, October 1 through September 30, in U.S. Geological Survey reports dealing with surface-water supply. The water year is designated by the calendar year in which it ends and which includes 9 of the 12 months. Thus, the year ending September 30, 1980, is called the "1980 water year."