Red List habitat classification > RLC - Freshwater habitats > RLC6.1 Underground standing and running waterbody

Underground standing and running waterbody

Quick facts

Red List habitat type code RLC6.1
Threat status
Europe Data Deficient
EU Data Deficient
Relation to
Source European Red List habitat factsheet
European Red List of habitats reports
European Red List of habitats (Excel table)


The habitat includes running or standing water bodies that develop under the ground surface. In many cases these water bodies are part of cave systems. Groundwater systems in soil are not included here. The underground water body is a result of impermeable layers below the body that enables accumulation of water. Water can also be captured between two impermeable layers (artesian water). This habitat most often develops on limestone bedrock. By dissolution of limestone, the water creates underground caves that can be filled with water. Specific animals are adapted to these conditions, such as Proteus anguinus the only cave-dwelling chordate species found in Europe. It is an entirely aquatic animal, as it eats, sleeps, and breeds underwater. This animal is most notable for its adaptations to a life of complete darkness: eyes are undeveloped and the animal is blind, while its other senses, particularly smell and hearing, are acutely developed. It has also no pigmentation in its skin. Underground water bodies are an important source for drinking water, and in that sense threatened by pollution. This habitat type can be connected with other habitats developing above the ground surface, like temporary flooded habitats, turloughs, poljes and others karst structures.

Indicators of good quality:

  • Unaltered stalactites, stalagmites or other carbonate concretions testifying an active karst phenomenon
  • No groundwater capture or canalization
  • Presence of invertebrate and vertebrate species typical of this habitat
  • No touristic use of the cave

Characteristic species
For full habitat description, please download the habitat factsheet.

Threat status

Synthesis of Red List assessment

Less than 20% of the countries in which the habitat occurs provided some quantitative or qualitative data. Although most of these countries stated that the habitat is stable or only slightly declining and/or damaged, any assessment would be based on very poor data. Very little is known on trends in quality, while the water quality may be negatively influenced by drainage of polluted surface water in many sites. For this reason the habitat type is overall assessed as Data Deficient (DD).
Red List Category Red List Criteria
Data Deficient -
Red List Category Red List Criteria
Data Deficient -

Confidence in the assessment

Red List of habitat categories and criteria descriptions

Pressures and threats

  • Human intrusions and disturbances
    • Sport and leisure structures
    • Other sport / Leisure complexes
    • Other human intrusions and disturbances
    • Trampling, overuse
    • Vandalism
    • Disturbance of species
  • Pollution
    • Pollution to groundwater (point sources and diffuse sources)
  • Natural System modifications
    • Human induced changes in hydraulic conditions
    • Water abstractions from groundwater
    • Saltwater intrusion of groundwater
  • Geological events, natural catastrophes
    • Earthquake
    • Undergound collapses

Habitat restoration potential

The capacity of this habitat to recover naturally or through intervention depends on the kind and severity of the damage that the habitat has undergone, by the geological substrate, the connection of the system with the surface and the time of groundwater renewal. The time for renewal of groundwater can naturally take thousands of years. Therefore, in case of water pollution, which is the most frequent cause of damage, after removal of the causes of pollution it may take decades or centuries to recover the habitat.

Trends in extent

Average current trend in quantity

Unknown Unknown
EU28 EU28+

Trends in quality

Average current trend in quality

Unknown Unknown
EU28 EU28+

Conservation and management needs

The measures that should be taken to preserve this habitat type are, consistently with the pressures and threats, those related to human activities that can alter the abiotic and biotic conditions of the habitat: (a) regulating the human access to the habitat for touristic and mining purposes, (b) regulating the water abstraction, (c) regulating the industrial and urban waste management to avoid that underground water systems can be directly or indirectly polluted, (d) improving or restoring the water quality whenever the habitat is already compromised.

List of conservation and management needs

  • No measures
    • Measures needed, but not implemented
  • Measures related to wetland, freshwater and coastal habitats
    • Restoring/Improving water quality
    • Restoring/Improving the hydrological regime
    • Managing water abstraction
  • Measures related to urban areas, industry, energy and transport
    • Urban and industrial waste management


For each habitat a distribution map was produced from a wide variety of sources indicating known and potential occurrences of the habitat in 10x10 km grids within Europe. Occurrences in grid cells were given in two classes: actual distribution from relatively reliable sources (surveys, expert knowledge), and potential distribution based on models or less reliable indicators. Please download the fact sheet to see the map.

Geographic occurrence and trends

EU28 Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Austria Present Unknown Stable Stable
Belgium Present Unknown Unknown Unknown
Bulgaria Present Unknown Decreasing Decreasing
Croatia Present Unknown Stable Stable
Czech Republic Present 0.02 Stable Stable
Estonia Present Unknown Unknown Unknown
France mainland Present Unknown Decreasing Unknown
Corsica Present Unknown Decreasing Unknown
Germany Present Unknown Stable Stable
Greece (mainland and other islands) Present Unknown Unknown Unknown
Crete Present Unknown Unknown Unknown
East Aegean Present Unknown Unknown Unknown
Hungary Present Unknown Unknown Unknown
Ireland Present Unknown Stable Stable
Italy mainland Present Unknown Unknown Unknown
Sardinia Present Unknown Unknown Unknown
Sicily Present Unknown Unknown Unknown
Latvia Present Unknown Unknown Unknown
Luxembourg Present Unknown Unknown Unknown
Malta Uncertain Unknown Unknown Unknown
Poland Present Unknown Unknown Unknown
Spain mainland Present 358 Unknown Decreasing
Balearic Islands Present 358 Unknown Decreasing
Canary Islands Present 358 Unknown Decreasing
Portugal mainland Present 200 Unknown Unknown
Portugal Azores Present 200 Unknown Unknown
Madeira Present 200 Unknown Unknown
Savage Islands Present 200 Unknown Unknown
Romania Present 45 Stable Stable
Slovakia Present 0.0001 Stable Stable
Slovenia Present Unknown Stable Stable
Sweden Present Unknown Unknown Unknown
United Kingdom Present Unknown Unknown Unknown
Northern Island Present Unknown Unknown Unknown
Gibraltar Uncertain Unknown Unknown Unknown
Cyprus Present Unknown Unknown Unknown
Denmark Uncertain Unknown Unknown Unknown
Lithuania Present Unknown Unknown Unknown
EU28 + Present or presence uncertain Current area of habitat (Km2) Recent trend in quantity (last 50 years) Recent trend in quality (last 50 years)
Albania Present Unknown Unknown Unknown
Bosnia and Herzegovina Present 25 Decreasing Stable
Kosovo Present Unknown Unknown Unknown
Former Yugoslavian Republic of Macedonia (FYROM) Present Unknown Unknown Unknown
Montenegro Present Unknown Unknown Unknown
Norway Mainland Present Unknown Unknown Unknown
Svalbard Present Unknown Unknown Unknown
Jan Mayen Present Unknown Unknown Unknown
Serbia Present Unknown Unknown Unknown
Switzerland Present Unknown Unknown Unknown
Liechtestein Uncertain Unknown Unknown Unknown

Extent of Occurrence, Area of Occupancy and habitat area

Extent of Occurrence (EOO) (Km2) Area of Occupancy (AOO) Current estimated Total Area Comment
EU28 11555150 7190 603 AOO and EOO incl. potential distribution
EU28+ 7191 628 AOO and EOO incl. potential distribution
AOO = the area occupied by a habitat measured in number of 10x10 km grid cells.
EOO = the area (km2) of the envelope around all occurrences of a habitat (calculated by a minimum convex polygon).

Characteristic species

The full list of characteristic species and genus are available above from the Summary. The species available in the EUNIS database are shown here.
Amphibians Atylodes genei
Amphibians Proteus anguinus
Invertebrates Gammarus lacustris
Species scientific name English common name Species group
Atylodes genei Amphibians
Proteus anguinus Olm Amphibians
Gammarus lacustris Invertebrates

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Other classifications

This habitat may be equivalent to, or broather than, or narrower than the habitats or ecosystems in the following typologies.
Classification Code Habitat type name Relationship type
EUNIS Habitat Classification 200711 H1.6 Underground running waterbodies wider
EUNIS Habitat Classification 200711 H1.5 Underground standing waterbodies wider
European Environment Agency (EEA)
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