Acre – 43,560ft2

Acre-foot – (Acre-ft, AF, AC-FT) The volume of water that would cover one acre of land (43,560 square feet, about the size of an average football field) to a depth of one foot, equivalent to 325,851 gallons of water. An acre-foot is the basic measure of agricultural water use. The average California family uses 2/3 of an acre-foot of water each year (afa = acre-ft per annum). The average crop uses three acre-feet of water in a growing season.

Alluvium – A general term for all detrital material deposited or in transit by streams, including gravel, sand, silt, clay, and all variations and mixtures of these.

Anastomosed Stream Type – a multi-tread channel system with a very low stream gradient and the bankfull width of each individual channel noted as highly variable.  The related valley morphology is seen as a series of broad, gently sloping wetland features developed on or within lacustrine deposits, river deltas, or splays, and fine-grained alluvial deposits.  Stream banks are often constructed with fine-grained cohesive materials, supporting dense-rooted vegetation species, and are extremely stable.

Appropriation Doctrine – (Also called Prior Appropriation Doctrine) the system for allocating water to private individuals used in most Western states. The doctrine of Prior Appropriation was in common use throughout the arid west as early settlers and miners began to develop the land. The prior appropriation doctrine is based on the concept of “First in Time, First in Right.” The first person to take a quantity of water and put it to Beneficial Use has a higher priority of right than a subsequent user. Under drought conditions, higher priority users are satisfied before junior users receive water. Appropriative rights can be lost through nonuse; they can also be sold or transferred apart from the land. Contrasts with Riparian Water Rights.

Aquifer – an underground layer of water-bearing permeable rock, or permeable mixtures of unconsolidated materials (gravel, sand, silt, or clay) (see also groundwater). Some productive aquifers are in fractured rock (carbonate rock, basalt, or sandstone). The study of water flow in aquifers and the characterization of aquifers is hydrogeology.

Artesian Water – ground water that is under pressure when tapped by a well and is able to rise above the level at which it is first encountered. It may or may not flow out at ground level. The pressure in such an aquifer commonly is called artesian pressure, and the formation containing artesian water is an artesian aquifer or confined aquifer.

Artificial Recharge – an process where water is put back into ground-water storage from surface-water supplies such as irrigation, or induced infiltration from streams or wells.

Avulsion – the sudden movement of soil from one property to another as the result of a flood or a shift in the course of a boundary stream.  Streamflow spilling out of the banks of the existing channels.  Channel avulsion typically occurs where the existing channel is incapable of carrying all of the water and sediment supplied to it.


Baseflow – streamflow coming from groundwater seepage into a stream or river. Groundwater flows underground until the water table intersects the land surface and the flowing water becomes surface water in the form of springs, streams/rivers, lakes and wetlands. Baseflow is the continual contribution of groundwater to rivers and is an important source of flow between rainstorms.

Bedrock – general term for consolidated (solid) rock that underlies soils or other unconsolidated material.

Benthic – refers to material, especially sediment, at the bottom of an aquatic ecosystem.  It can be used to describe the organisms that live on, or in, the bottom of a water body.  Benthic organisms are not free-floating like pelagic organisms.

Benthos – biota that live on or near the bottom of a body of water.  Both mobile and non-mobile.


Capillary Action – the movement of water in the interstices of a porous medium due to capillary forces (after ASTM, 1980). The depression or elevation of the meniscus of a liquid contained in a tube of small diameter due to the combined effects of gravity, surface tension, and the forces of cohesion and adhesion.

CFS – Cubic-Feet per second. 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. The volume of water represented by a flow of 1 cubic foot per second for 24 hours is equivalent to 86,400 cubic feet, approximately 1.983 AF, or 646,272 gallons.

Channel Flow – The volume of water in transit in a system between inflow and outflow.

Chute Cutoffs – small channels cutting across a point-bar.

Circuli – concentric lines of the smooth, flat, round scalles (called cycloid scales) found on trout, herring, and other fish.  Circuli act like growth rings on a tree.  They can tell how old a fish is, and how fast it grew each year.  This can give a clue to the life history of the fish.

Commercial Water Use – water used for motels, hotels, restaurants, office buildings, other commercial facilities, fish hatcheries, and civilian and military institutions as classified by Standard Industrial Classification (SIC) or North American Industrial Classification codes.

Condemnation – See “Eminent Domain”

Condensation – the process by which a substance changes from a vapor or gaseous state to a liquid form, as water vapor in the air condenses into droplets of liquid on the outside of a cold drinking glass. The condensation of water vapor into clouds and precipitation is a vital link in the hydrologic cycle.

Consumptive Use – that part of water withdrawn that is evaporated, transpired, incorporated into products or crops, consumed by humans or livestock, or otherwise removed from the immediate water environment. Also referred to as water consumed.

Conveyance Loss – water that is lost in transit from a pipe, canal, conduit, or ditch by leakage or evaporation. Generally, the water is not available for further use; however, leakage from an irrigation ditch, for example, may percolate to a ground-water source and be available for further use.


Discharge – the volume of water (or more broadly, volume of fluid plus suspended sediment) that passes a given point within a given period of time.

Domestic Water Use – water for household purposes, such as drinking, food preparation, bathing, washing clothes and dishes, flushing toilets, and watering lawns and gardens. Also called residential water use. The water may be obtained from a public supply or may be self supplied.

Drainage Basin – See “Watershed”

Drawdown – the lowering of the surface elevation of a body of water, the water surface of a well, the water table, or the piezometric surface adjacent to the well, resulting from the withdrawl of water therefrom.

Drip Irrigation – a method of microirrigation wherein water is applied to the soil surface as drops or small streams through emitters. Discharge rates are generally less than 8 Liters/hour (2 gal/hour) for single-outlet emitters and 12 Liters/hour (3 gal/hour) per meter for line-source emitters ASAE.)


Eminent Domain – (also know as condemnation) is the taking of title to private land by a public agency or publicly regulated utility company

Endemic Species – Plants or animals that occur naturally in a certain region and whose distribution is relatively limited to a particular locality.  Enimism is the occurance of endemic species in an area.

Erosion – the wearing away of land surface by wind or water, intensified by land-clearing practices related to farming, residential or industrial development, road building, or logging.

Evaporation – The change of state of liquid, from a liquid to a vapour state, below the boiling point of the liquid. Has the effect of cooling the liquid as it is the molecules with the highest kinetic energies which escape into the atmosphere through the liquid surface. This results in a drop of the average kinetic energy of all the molecules in the liquid, and consequently a fall in temperature. The calculation of evaporative losses is very complex. Most areas have a meteorological office who can provide approximations of evaporative losses for the area.

Evapotranspiration – the evaporation of water from the soil and the transpiration of water from the plants that live in that soil. Approximately one-quarter of a forest’s annual rainfall returns to the air through evapotranspiration.


Floodplain – land immediately adjoining a stream which is inundated when the discharge exceeds the conveyance of the normal channel. The channel proper and the areas adjoining the channel which have been or hereafter may be covered by the regulatory or 100-year flood. Any normally dry land area that is susceptible to being inundated by water from any natural source. The floodplain includes both the floodway and the floodway fringe districts.

Flood Routing – The computation of inflow, outflow and storage for a reach of river

Freshwater – water that contains less than 1,000 milligrams per liter (mg/L) of dissolved solids; generally, more than 500 mg/L of dissolved solids is undesirable for drinking and many industrial uses.


Geometric Mean – a measure of the central tendancy of a data set that minimizes the effects of extreme values.

Groundwater – generally all subsurface water as distinct from surface water; specifically, that part of the subsurface water in the saturated zone (a zone in which all voids are filled with water) where the water is under pressure greater than atmospheric.


Headwater(s) – 1.) the source and upper reaches of a stream; also the upper reaches of a reservoir. 2.) the water upstream from a structure or point on a stream. (3) the small streams that come together to form a river. Also may be thought of as any and all parts of a river basin except the mainstream river and main tributaries.

Humus – decomposed organic matter.  Healthy soil will consist of about 3.5 to 5% of this organic matter.  Humus is soft, sweet-smelling, shapeless dark, and crumbly, and smells like the forest floor (more correctly, the forest floor smells like humus because that is what it is made of).  It is this stage of the decomposition process which provides nutrients for plant life.  It contains about 30% each of lignin, protein, and complex sulfars.  It contains 3-5% Nitrogen and 55-60% carbon (which can’t be right, because that all adds up to 155%, but that is what I have written in my notes).  Humus is the slow-release food source for microorganism development.  It is constantly being transformed into acids, enzymes, and minerals, and, therefor, must be constantly replenished for proper vegetative nutrition.

Hydrologic Cycle – A model describing the movement of water above, on, and in the Earth. Can be shown mathematically as Precipitation = Run Off + EvapoTranspiration + Infiltration + Storage (P=RO+ET+I+S)

Hypatic Circulation – circulation of blood through the liver.


Infiltration – the passage of water through the soil surface into the soil.

Instream Use – water that is used, but not withdrawn, from a surface-water source for such purposes as hydroelectric-power generation, navigation, water-quality improvement, fish propagation, and recreation.

Irrigation Water Use – water that is applied by an irrigation system to assist in the growing of crops and pastures or to maintain vegetative growth in recreational lands such as parks and golf courses. Irrigation includes water that is applied for pre-irrigation, frost protection, chemical application, weed control, field preparation, crop cooling, harvesting, dust suppression, the leaching of salts from the root zone, and water lost in conveyance.




Lacustrine – 1.) of, or pertaining to a lake.  2.) Deposits laid down in relatively still-water lakes – May be detrital or organic material, or clays and silts.  Lacustrine is related to the word “Lake.”  Thus a lacustrine wetland is, by definition, lake-associated.  This category may include freshwater marshed, aquatic beds, as well as lake shores.  Distinctions between lacustrine and palustrine habitat are primarily contingent on the way in which lake is defined.

Land – 1.) Physical material: soil, minerals (subsurface mineral rights), and vegetation.   2.) Real Estate – land as property.   3.) Capital Value – land has instrument value.

Lentic – of, or relating to, or living in still waters.  Lentic tends to be used for freshwater habitats.  Some examples of lentic environments are lakes, ponds, and flooded forests.  Deeper standing water, like a lake, is affected by strong stratification.  There is an upper layer and a lower layer seperated by a narrow in-between layer of water.  The upper layer of water has higher oxygen, more light, more plankton, and tends to be warmer that the lower layer.  Contrast with lotic.

Levee – tn hydrologic terms, a long, narrow embankment usually built to protect land from flooding. If built of concrete or masonary the structure is usually referred to as a flood wall. Levees and floodwalls confine streamflow within a specified area to prevent flooding. The term “dike” is used to describe an embankment that blocks an area on a reservoir or lake rim that is lower than the top of the dam.

Lotic – of, or relating to, or living in actively moving water.  Lotic tends to be used for freshwater habitats.  Some examples of lotic habitats are rivers and streams.  In lotic water, most fish prefer deeper, slow-moving areas of water to shallow, fast-moving waters in the same stream or river.  In a fast current, the fish must use more energy to keep from being carried downstream.  Fish also tend to prefer vegetation because it protects them from predators.  Contrast with lentic.


Mining Water Use – water use for the extraction of minerals occurring naturally including solids, such as coal and ores; liquids, such as crude petroleum; and gases, such as natural gas. Also includes uses associated with quarrying, well operations (dewatering), milling (crushing, screening, washing, floatation, and so forth), and other preparations customarily done at the mine site or as part of a mining activity. Does not include water used in processing, such as smelting, refining petroleum, or slurry pipeline operations. These uses are included in industrial water use.




Palustrine – vegetated wetlands dominated by trees, shrubs, and persistant emergents.  Comes from the Latin word “palus” which means marsh.  Wetlands in this category include areas traditionally called marsh, swamp, bog, fen, prarie, and also includes small, shallow, permanent or intermittent water bodies called ponds less than 6.6ft deep.  Ant inland wetland which lacks flowing water and conains ocean-derived salts of less than .05%.  Except for ponds, palustrine bodies are situated shoreward of lakes, river channels, and large river enbayments.

Particle Size – in dealing with sediments and sedimentary rocks it is necessary that precise dimensions should be applied to such terms as clay, sand, pebble, etc. Numerous scales have been suggested, but in this work, the Wentworth-Udden scale is used, as it is widely accepted as an international standard. Particle size is normally determined by hand measurement of pebbles, cobbles, and boulders; sieving of gravel, sand, and silt; and elutriation of silt and clay. Boulder: >256 mm; Cobble: 64 – 256 mm; Pebble: 4 – 64 mm; Gravel: 2 – 4 mm; Sand: 1/16 – 2 mm; Silt: 1/256 – 1/16 mm; Clay: <1/256 mm.

Peak Flow – maximum flow through a watercourse which will recur with a stated frequency. The maximum flow for a given frequency may be based on measured data, calculated using statistical analysis of peak flow data, or calculated using hydrologic analysis techniques. Projected peak flows are used in the design of culverts, bridges, and dam spillways.

Pelagic – refers to fish and animals that live in the open sea, away from the sea bottom.  Pelagic organisms swim through the ocean, and may rise to the surface or sink to the bottom.  They are not confined to the bottom like benthic organisms.  Pelagic organisms are generally free-swimming (nektonic) or ploating (planktonic).

Percolation – the actual movement of subsurface water either horizontally or vertically; lateral movement of water in the soil subsurface toward nearby surface drainage feature (eg stream) or vertical movement through the soil to groundwater zone.

Permeability – a measure of the rate at which water will flow into or through soil or rocks.

Phytotoxic – toxic, damaging or harmful to plants, often by destroying the protective surface on plant leaves.  Partially composted organic matter may have acids or alchohols present that will harm young or sensitive plants.  Partially-decomposed compost is therefore refered to as phytotoxic.  The property of a substance at a specific concentration that restricts or constrains plant growth.

Phytotoxin – any substance produced by plants that is similar in properties to extracellular bacterial toxin.  Plant toxin.

Porosity – is a measure of the voids in unconsolidated sediments or bedrock. It is the ratio of volume of openings to the total volume of the material.

Piscary – fishery: a workplace where fish are caught and processed and sold.

Prior Appropriation Doctrine – See “Appropriation Doctrine”

Public Supply – water withdrawn by public governments and agencies, such as a county water department, and by private companies that is then delivered to users. Public suppliers provide water for domestic, commercial, thermoelectric power, industrial, and public water users. Most people’s household water is delivered by a public water supplier. The systems have at least 15 service connections (such as households, businesses, or schools) or regularly serve at least 25 individuals daily for at least 60 days out of the year.

Public Water Use – water supplied from a public-water supply and used for such purposes as firefighting, street washing, and municipal parks and swimming pools.


Quasi-Equilibrium – unimpaired by humans, natural river conditions are balanced, where the size and form of the channel is maintined by the flow of water and sediment with only slow and gradual change.


Recharge – mechanisms of inflow to the aquifer. Typical sources of recharge are precipitation, applied irrigation water, underflow from tributary basins and seepage from surface water bodies.

Reservoir – a pond, lake, or basin, either natural or artificial, for the storage, regulation, and control of water.

Riffle – a protuberance on the bed of a stream.  A topographic high.

Riparian Water Rights – the rights of an owner whose land abuts water. They differ from state to state and often depend on whether the water is a river, lake, or ocean. The doctrine of riparian rights is an old one, having its origins in English common law. Specifically, persons who own land adjacent to a stream have the right to make reasonable use of the stream. Riparian users of a stream share the streamflow among themselves, and the concept of priority of use (Prior Appropriation Doctrine) is not applicable. Riparian rights cannot be sold or transferred for use on nonriparian land.

Runoff – 1.) That part of the precipitation, snow melt, or irrigation water that appears in uncontrolled surface streams, rivers, drains or sewers. Runoff may be classified according to speed of appearance after rainfall or melting snow as direct runoff or base runoff, and according to source as surface runoff, storm interflow, or ground-water runoff. 2.) The total discharge described in #1, above, during a specified period of time. 3.) Also defined as the depth to which a drainage area would be covered if all of the runoff for a given period of time were uniformly distributed over it.


Saline Water – water that contains significant amounts of dissolved solids. Fresh water – Less than 1,000 parts per million (ppm); Slightly saline water – From 1,000 ppm to 3,000 ppm; Moderatly saline water – From 3,000 ppm to 10,000 ppm; Highly saline water – From 10,000 ppm to 35,000 ppm

Sediment – solid fragmental matter, either inorganic or organic, that originates from weathering of rocks and is transported and deposited by air, water, or ice, or that is accumulated by other natural agents, such as chemical precipitation from solution or secretion from organisms. When deposited, it generally forms layers of loose, unconsolidated material (for example, sand, gravel, silt, mud, till, loess, alluvium).

Sinkhole – a depression in the Earth’s surface caused by dissolving of underlying limestone, salt, or gypsum. Drainage is provided through underground channels that may be enlarged by the collapse of a cavern roof.

Splash Dams – dames used in logging to impound water on small streams.  The water from several dams was released in a coordinated fashion to supply a “tide” of water to float large logs.

Spray Irrigation – an common irrigation method where water is shot from high-pressure sprayers onto crops. Because water is shot high into the air onto crops, some water is lost to evaporation.

Stream – a general term for a body of flowing water; natural water course containing water at least part of the year. In hydrology, it is generally applied to the water flowing in a natural channel as distinct from a canal.

Subsidence – a settling of the ground surface caused by the collapse of porous formations that result from withdrawal of large amounts of groundwater, oil, or other underground materials.

Surface Water – water that sits or flows above the earth, including lakes, oceans, rivers, and streams.

Suspended Sediment – very fine soil particles that remain in suspension in water for a considerable period of time without contact with the bottom. Such material remains in suspension due to the upward components of turbulence and currents and/or by suspension.

Suspended Solids – solids that are not in true solution and that can be removed by filtration. Such suspended solids usually contribute directly to turbidity. Defined in waste management, these are small particles of solid pollutants that resist separation by conventional methods.


Teleost – any member of the infraclass Teleostei, a large and extremely diverse group of ray-finned fishes.  Along with the Chondrosteans and the Holosteans, they are one of the threthat part of water withdrawn that is evaporated, transpired, incorporated into products or crops, consumed by humans or livestock, or otherwise removed from the immediate water environment. Also referred to as water consumed.e major subdivisions of the class Actinopterygii, the most advanced of the bony fisheds.  Includes 95% of the world’s fish species.

Thalweg – line of deepest water in a stream.  The thalweg is the part that has the maximum velocity and causes cutbanks and channel migrations.that part of water withdrawn that is evaporated, transpired, incorporated into products or crops, consumed by humans or livestock, or otherwise removed from the immediate water environment. Also referred to as water consumed.

Transpiration – the process in which water is absorbed by the root systems of plants, moves up through the plant (via the xylem), passes through pores (stomata) in the leaves and other plant parts, and then evaporates into the atmosphere as water vapor.

Turbidity – the cloudy appearance of water caused by the presence of suspended and colloidal matter. In the waterworks field, a turbidity measurement is used to indicate the clarity of water. Technically, turbidity is an optical property of the water based on the amount of light reflected by suspended particles. Turbidity cannot be directly equated to suspended solids because white particles reflect more light than dark-colored particles.

Turgor – the normal rigid state of fullness of a cell or blood vessel or capillary resulting from pressure of the contents against the wall or membrane.


Unsaturated Zone – the zone between the land surface and the regional water table. Generally, fluid pressure in this zone is less than atmospheric pressure, and some of the voids may contain air or other gases at atmospheric pressure. Beneath flooded areas or in perched water bodies, the fluid pressure locally may be greater than atmospheric.



Wastewater – water that has been used in homes, industries, and businesses that is not for reuse unless it is treated.

Water Cycle – See “Hydrologic Cycle”

Watershed – (also called Drainage Basin) the land above a given point on a waterway that contributes runoff water to the flow at that point; a drainage basin or a major subdivision of a drainage basin.

Water Table – The level of ground water. The upper surface of the zone of saturation of groundwater above an impermeable layer of soil or rock (through which water cannot move) as in an unconfined aquifer. This level can be very near the surface of the ground or far below it.

Water Use – water that is used for a specific purpose, such as for domestic use, irrigation, or industrial processing. Water use pertains to human’s interaction with and influence on the hydrologic cycle, and includes elements, such as water withdrawal from surface- and ground-water sources, water delivery to homes and businesses, consumptive use of water, water released from wastewater-treatment plants, water returned to the environment, and instream uses, such as using water to produce hydroelectric power.