ACRE-FOOT (AF): A unit commonly used to measure volume of water; equal to 43,560 cubic
feet, or 325,861 gallons (will cover one acre one foot deep).
AQUIFER: A geologic formation that stores and/or transmits water. A CONFINED AQUIFER
is bounded above and below by formations of impermeable or relatively impermeable material.
An UNCONFINED AQUIFER is made up of loose material, such as sand or gravel, that has not
CONFLUENCE: A meeting or junction of two or more streams.
DEPLETION (GROUNDWATER): The withdrawal of water from a ground water source at a
rate greater than its rate of recharge.
EPHEMERAL: As it relates to source dependability small, shallow stockponds that dry up
following a single storm event; streams that flow only in direct response to precipitation, lasting no more than several weeks. See perennial, intermittent.
FLOOD PLAIN: A relatively flat area bordering a stream or adjoining a body of standing water that may be overflowed during times of high water.
GROUNDWATER: Water under ground, such as in wells, springs, and aquifers.
HEADWATERS: The source and upper reaches of a stream or reservoir; small streams that
come together to form a river.
HISTORIC FLOW: The flow that has occurred and was or would have been recorded at a gaging station.
HYDROLOGIC CYCLE: The circuit of water movement from the atmosphere to the earth and return to the atmosphere through various stages or processes such as precipitation, interception, runoff, infiltration, percolation, storage, evaporation and transportation.
IMPERMEABLE: Unable to transmit water; not easily penetrated.
INTERMITTENT, STREAM: As it relates to source dependability springs that discharge only during certain periods but at other times of the year are dry; streams with alternating surface and subsurface flow; no intermittent stockponds (see ephemeral or seasonal).
RESERVOIR: A pond, lake, or basin, either natural or artificial, for the storage, regulation, and control of water.
RIGHTS-OF-WAYS: Permission granted by land owners for the use of that land for specific projects.
RIPARIAN DOCTRINE: The legal right to use water by an owner of land contiguous to or bordering on a natural stream or lake.
RIPARIAN: Pertaining to the banks of a river, stream, or other body of water as well as to plant and animal communities along such bodies of water.
SEASONAL: As is relates to source dependability springs and wells that exist only during
periods of high water levels, stockponds where water is available during and after periods of seasonal precipitation but not year-round.
SPRING: Groundwater seeping or flowing out of the Earth’s surface without the aid of man;
springs occur where the water table reaches the surface.
STREAM: A general term for a body of flowing water. In hydrology the term is generally
applied to the water flowing in a natural channel as distinct from a ditch or canal. Types of streams:
- EPHEMERAL – A stream which flows only in direct response to precipitation, and whose
channel is at all times above the water table.
- INTERMITTENT OR SEASONAL – A stream which flows only at certain times of the year when it received water from springs, rainfall, or from surface sources such as melting snow.
- PERENNIAL – A stream which flows continuously.
- GAINING – A stream or reach of a stream that receives water from groundwater.
- LOSING – A stream or reach of a stream that contributes to groundwater.
SURFACE WATER: All waters whose surface is naturally exposed to the atmosphere, e.g., rivers, lakes, reservoirs, impoundments, springs.
WATER TABLE: The top of an unconfined aquifer; indicates the level below which soil & rock are saturated with water.