Aquifer is a porous rock structure within which water travels and is stored. Aquifers may be shallow, a few metres in depth, or very deep being several hundred metres in depth.
Artificial water body is a body of surface water created by human activity. It is known as a heavily modified water body if, as a result of physical alterations by human activity, it is changed substantially in character as designated by an individual Member State and in accordance with the provisions of Annex II of the Water Framework Directive.
Coastal water is that area of surface water on the landward side of a line, every point of which is at a distance of one nautical mile on the seaward side from the nearest point of the baseline from which the breadth of territorial waters is measured, extending where appropriate up to the outer limit of transitional waters.
Diffuse sources (of pollution) are primarily associated with run-off and other discharges related to different land uses such as agriculture and forestry, from septic tanks associated with rural dwellings and from the land spreading of industrial, municipal and agricultural wastes.
Ecological status is an expression of the structure and functioning of aquatic ecosystems associated with surface waters. Such waters are classified as being of good ecological status when they meet the requirements of the Directive.
Emission limit value means the amount of a substance, usually expressed as a concentration and/or a level, which may not be exceeded during any one or more periods of time.
Emission controls are controls which are placed on emissions (point sources) requiring a specified emission limit value.
Environmental objectives are objectives set out in Article 4 of the Directive. These define the environmental goals which must be achieved.
Environmental quality standard means the concentration of a particular pollutant or group of pollutants in water, sediment or in aquatic life which should not be exceeded in order to protect human health and the environment.
Evaporation is the transformation of liquid water into vapour as a result of heating.
Good status is a general term meaning the status achieved by a surface water body when both the ecological status and its chemical status are at least good or, for groundwater, and when both its quantitative status and chemical status are at least good.
Good surface water status is when both its ecological status and its chemical status are at least good and a surface water body is regarded as being of good status.
Good surface water chemical status means that concentrations of pollutants in the water body do not exceed the environmental limit values specified in the Directive.
Good groundwater status is that achieved by a groundwater body when both its quantitative status and chemical status are good.
Groundwater is all water which is below the surface of the ground in the saturation zone and in direct contact with the ground or subsoil. This zone is commonly referred to as an aquifer which is a subsurface layer or layers of rock or other geological strata of sufficient porosity and permeability to allow a significant flow of groundwater or the abstraction of significant quantities of groundwater.
Hydrological means pertaining to water.
Hydrological cycle (sometimes called the water cycle) is the movement of water from the atmosphere to the land as precipitation, its flow to the sea via rivers and lakes and the return to the atmosphere via evaporation.
Inland water is all standing or flowing water on the surface of the land (such reservoirs, lakes, rivers and coastal waters) and all groundwater on the landward side of the baseline from which the breadth of territorial waters is measured.
Lake is a body of water, which may be man-made or natural, occurring on the land surface.
Point sources (of pollution) are primarily discharges from municipal wastewater treatment plants associated with population centres or effluent discharges from industry.
Polluter pays principle is enshrined within the Directive requiring that the polluter of the water environment should pay, provided this is established through fair pricing policies.
Precipitation is the release of water from the atmosphere as rain, snow or hail.
Programme of measures defines in detail those actions which are required to achieve the environmental objectives of the Directive within a River Basin District.
Quantitative status is an expression of the degree to which a body of groundwater is affected by direct and indirect abstractions. If this complies with Directive requirements the status is good.
River is a body of inland water flowing for the most part on the surface of the land but which may flow underground for part of its course. Upland rivers are generally fast flowing and lowland rivers are generally slow flowing and meandering.
River basin means the area of land from which all surface water run-off flows, through a sequence of streams, rivers and lakes into the sea at a single river mouth, estuary or delta.
River Basin District is a river catchment or a group of catchments.
River basin management plan is a detailed document describing the characteristics of the basin, the environmental objectives that need to be achieved and the pollution control measures required to achieve these objectives through a specified work programme.
Soil water is water held within or travelling through soil which is within the reach of plants.
Surface water means inland waters, except groundwater, which are on the land surface (such as reservoirs, lakes, rivers, transitional waters, coastal waters and, under some circumstances, territorial waters) which occur within a river basin.
Transitional waters are bodies of surface water in the vicinity of river mouths which are partly saline in character as a result of their vicinity to coastal waters, but which are substantially influenced by freshwater flows.
Water body is a discrete and significant element of surface water such as a river, lake or reservoir, or a distinct volume of groundwater within an aquifer.