Classification Glossary

Definitions and Descriptions for the Cowardin Classification

Hierarch: System-Subsystem-Class-Subclass-Modifier


  • Lacustrine: deepwater habitats with all the following characteristics:

    1. Situated in a topographic depression or damned river channel.

    2. Lacking trees, shrubs, persistent emergents, emergent mosses, or lichens with greater than 30% areal coverage.

    3. Total area exceeds 20 acres. Areas less than 20 acres may be included in the lacustrine system if an active wave formed or bedrock shoreline makes up all or part of the boundary, or if water is greater than 6.6 feet in the deepest part of the basin at low water.

  • Palustrine: area dominated by trees, shrubs, persistent emergents, emergent mosses, or lichens. Areas lacking such vegetation are also included if they have all of the following characteristics :

    1. Area less than 20 acres ( 8 hectares).

    2. No active wave formed or bedrock shoreline.

    3. Water depth in deepest part of basin less than 6.6 feet ( 2 meters ) at low water. May be situated at the edge of a lake or river or in river floodplain.

  • Riverine: wetland and deepwater habitats contained within a channel with periodically or continuously moving water.


  • Intermittent: flowing water present only part of the year. When water is not flowing, it may remain in isolated pools or surface water may be present.

  • Limnetic: deep water (greater than 6.6 feet).

  • Littoral: from shore to a depth of 6.6 feet.

  • Lower perennial: water velocity slow, but some water flows throughout the year. Gradient is low. The substrate consists of sand and mud. Oxygen deficits may occur.

  • Upper perennial: gradient high, water velocity fast. Water flows throughout the year. Substrate consists of rock, cobble, gravel, and sand. Dissolved oxygen content high.


  • Aquatic bed: this includes wetlands and deepwater habitats dominated by plants that grow principally on or below the surface of the water for most of the growing season in most years.

  • Emergent: vegetation includes erect, rooted herbaceous hydrophytes representing more than 30% of the areal cover.

  • Persistent: vegetation remains upright and visible throughout the year.

  • Non-persistent: vegetation dies back and is not visible during the non-growing season.

  • Forested: woody vegetation that is 6m tall or taller covering 30% or more of the area.

  • Open water: non-vegetated areas less than 20 acres that are covered by water less than6.6 ft (2m) deep. This includes ponds, borrow pits, small reservoirs, and open water areas within a marsh or swamp.

  • Rock bottom: areas with stone, boulder, or bedrock cover 75% or more, vegetative cover <30%, and permanently flooded.

  • Rocky shore: areas with 75% or more bedrock, stones, or boulders, vegetative cover <30%, and not permanently flooded.

  • Scrub-shrub: characterized by woody vegetation less than 20 ft (6m) covering 30 % or more of the area.

  • Stream bed: areas where channel is completely dry at low water periods and vegetative cover <30%.

  • Unconsolidated bottom: wetlands in which the substrate is at least 25% particles smaller than stones, vegetative cover < 30 %, and permanently flooded.

  • Unconsolidated shore: areas with less than 75% coverage of bedrock, stone, or boulders, vegetative cover < 30%, and not permanently flooded.


Water regime

  • Artificially flooded: flooding controlled by pumps or siphons in combination with dikes or dams.

  • Intermittently exposed: surface water throughout the year except in extreme droughts.

  • Intermittently exposed/permanent: see definitions for intermittently exposed and permanently flooded.

  • Intermittently flooded: substrate usually exposed, variable presence of surface water without detectable seasonal periodicity.

  • Permanently flooded: surface water throughout the year in all years.

  • Saturated: substrate saturated to the surface for extended periods during the growing season but surface water seldom present.

  • Seasonally flooded: surface water for extended periods in growing season but not at the end of the growing season.

  • Semipermanently flooded: surface water throughout the growing season in most years.

  • Temporarily flooded: surface water for only brief periods during the growing season with the water table well below the soil surface for most of the season.

  • Special modifier

  • Artificial substrate: substrates placed by humans.

  • Beaver: created by beaver activity.

  • Diked/impounded: barrier obstructs inflow (dike) or outflow (impoundment) of water.

  • Excavated: lies in a basin or channel excavated by humans.

  • Farmed: altered for the production of crops but hydrophytes could reestablish.

  • Partially drained/ditched: artificially drained but can still support hydrophytes.

  • Spoil: refuse material removed from an excavation.