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General Description

Open water is defined as water lying beyond the limits of swamp or emergent vegetation, although it may contain submerged, free-floating or floating-leaved vegetation. The dominant species of any such vegetation should be coded, and the salinity of the water, whether fresh or brackish, indicated if possible. Where aquatic vegetation is present in quantity but there is insufficient room to code all abundant species, a target note should be provided. Details of the trophic status of the water can also be provided.

G1 Standing water Description

Standing water includes lakes, reservoirs, pools, flooded gravel pits, ponds, water-filled ditches, canals and brackish lagoons. Details of the trophic status of the water can also be provided.

• G1.1 Standing water - eutrophic Description - Standing water includes lakes, reservoirs, pools, flooded gravel pits, ponds, water-filled ditches, canals and brackish lagoons. Physical characteristics of eutrophic waters: water often strongly discoloured by algae; pH usually over 7; substrate often highly organic mud. Typical plant species of eutrophic waters: Lemna spp., Myriophyllum spicatum, Potamogeton pectinatus, Ceratophyllum spp., Zannichellia palustris, Ranunculus circinatus, Polygonum amphibium, Chara spp., Nuphar lutea, Ranunculus penicillatus var. calcareus is typical of flowing waters.
• G1.2 Standing water - mesotrophic Description - Standing water includes lakes, reservoirs, pools, flooded gravel pits, ponds, water-filled ditches, canals and brackish lagoons. Physical characteristics of mesotrophic waters: water sometimes discoloured by planktonic algae; pH usually around or slightly below neutral. Typical plant species of mesotrophic waters: Potamogeton gramineus, P. obtusifolius, P. perfoliatus, Callitriche hermaphroditica, Nitella spp., Nuphar lutea, Nymphaea alba.
• G1.3 Standing water - oligotrophic Description - Standing water includes lakes, reservoirs, pools, flooded gravel pits, ponds, water-filled ditches, canals and brackish lagoons. Physical characteristics of oligotrophic waters: water very clear, plankton sparse; pH usually less than 7; substrate rocky, sandy or peaty. Typical plant species of oligotrophic waters: Potamogeton polygonifolius, Myriophyllum alterniflorum, Juncus bulbosus, Scripus fluitans, Subularia aquatica, Lobelia dortmanna, Isoetes lacustris, Sparganium angustifolium, Callitriche hamulata, Flowing waters dominated by bryophyes.
• G1.4 Standing water - dystrophic Description - Standing water includes lakes, reservoirs, pools, flooded gravel pits, ponds, water-filled ditches, canals and brackish lagoons. Physical characteristics of dystrophic waters: water usually peat-stained; pH very low (3.5 - 5.5); alkalinity very low (up to 2mg/l CaCO3). Typical plant species of dystrophic waters: Sphagnum spp., Juncus bulbosus, Potamogeton polygonifolius, Macrophyte flora very restricted.
• G1.5 Standing water - marl Description - Standing water includes lakes, reservoirs, pools, flooded gravel pits, ponds, water-filled ditches, canals and brackish lagoons. Physical characteristics of marl waters: may be eutrophic, mesotrophic (or very rarely) oligotrophic; water very clear; alkalinity at least 100mg/l CaCO3; powdery yellow-brown deposit of marl covers substrate in lakes; highly calcareous streams deposit tufa. Typical plant species of marl waters: Chara spp., Myriophyllum spicatum, Potamogeton lucens.
• G1.6 Standing water - brackish Description - Standing water includes lakes, reservoirs, pools, flooded gravel pits, ponds, water-filled ditches, canals and brackish lagoons. Physical characteristics of brackish waters: most brackish systems are coastal but a few are inland, with salinity derived from artificial sources such as mine drainage, or form residues or ancient marine incursions in peaty areas; conductivity 1,250 to 50,000 µmhos.Typical plant species of brackish waters: flora very restricted:
  • Slightly saline waters -
    • Potamogeton pectinatus
    • P. pusillus
    • Myriophyllum spicatum
    • Zannichellia palustris
    • Ceratophyllum submersum
    • Ranunculus baudotii
    • Enteromorpha spp.
  • More saline waters -
    • Ruppia spp,
    • Fucoi
    • Zostera spp.

G2 Running water Description

Running water comprises rivers and streams. The direction of flow should be indicated by an arrow. Details of the trophic status of the water can also be provided.

• G2.1 Running water - eutrophic Description - Running water comprises rivers and streams. The direction of flow should be indicated by an arrow. Physical characteristics of eutrophic waters: water often strongly discoloured by algae; pH usually over 7; substrate often highly organic mud. Typical plant species of eutrophic waters: Lemna spp., Myriophyllum spicatum, Potamogeton pectinatus, Ceratophyllum spp., Zannichellia palustris, Ranunculus circinatus, Polygonum amphibium, Chara spp., Nuphar lutea, Ranunculus penicillatus var. calcareus is typical of flowing waters.
• G2.2 Running water - mesotrophic Description - Running water comprises rivers and streams. The direction of flow should be indicated by an arrow. Physical characteristics of mesotrophic waters: water sometimes discoloured by planktonic algae; pH usually around or slightly below neutral. Typical plant species of mesotrophic waters: Potamogeton gramineus, P. obtusifolius, P. perfoliatus, Callitriche hermaphroditica, Nitella spp., Nuphar lutea, Nymphaea alba. 
• G2.3 Running water - oligotrophic Description - Running water comprises rivers and streams. The direction of flow should be indicated by an arrow. Physical characteristics of oligotrophic waters: water very clear, plankton sparse; pH usually less than 7; substrate rocky, sandy or peaty. Typical plant species of oligotrophic waters: Potamogeton polygonifolius, Myriophyllum alterniflorum, Juncus bulbosus, Scripus fluitans, Subularia aquatica, Lobelia dortmanna, Isoetes lacustris, Sparganium angustifolium, Callitriche hamulata. Flowing waters dominated by bryophyes. 
• G2.4 Running water - dystrophic Description - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - Running water comprises rivers and streams. The direction of flow should be indicated by an arrow. Physical characteristics of dystrophic waters: water usually peat-stained; pH very low (3.5 - 5.5); alkalinity very low (up to 2mg/l CaCO3). Typical plant species of dystrophic waters: Sphagnum spp., Juncus bulbosus, Potamogeton polygonifolius, Macrophyte flora very restricted. 
• G2.5 Running water - marl Description - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - Running water comprises rivers and streams. The direction of flow should be indicated by an arrow. Physical characteristics of marl waters: may be eutrophic, esotrophic (or very rarely) oligotrophic; water very clear; alkalinity at least 100mg/l CaCO3; powdery yellow-brown deposit of marl covers substrate in lakes; highly calcareous streams deposit tufa. Typical plant species of marl waters: Chara spp., Myriophyllum spicatum, Potamogeton lucens. 
• G2.6 Running water - brackish Decription - (* This Phase 1 alphanumeric reference code differs from that used in either the 1984 NCC/RSNC classification or the 1982 SSSI mapping system.) - Running water comprises rivers and streams. The direction of flow should be indicated by an arrow. Typical plant species of brackish waters: flora very restricted:
  • Slightly saline waters -
    • Potamogeton pectinatus
    • P. pusillus
    • Myriophyllum spicatum
    • Zannichellia palustris
    • Ceratophyllum submersum
    • Ranunculus baudotii
    • Enteromorpha spp.
  • More saline waters -
    • Ruppia spp,
    • Fucoi
    • Zostera spp.