Key D-1:  Key to Water Flow Paths


1. Wetland is periodically flooded by tides......................................................Bidirectional-tidal See Key F-2 for additional descriptors based on tidal ranges (i.e., macrotidal, mesotidal, and microtidal).

  1. Wetland is not flooded by tides.        2


  1. Water levels fluctuate due to lake influences or to variable river levels, but water does not flow through this wetland.............................................................................Bidirectional-nontidal


Note: Lentic wetlands with streams running through them are classified as Throughflow to emphasize this additional water source, while lentic wetlands located in coves or fringing the high ground would typically be classified as Bidirectional-Nontidal.

Similarly, many floodplain wetlands are throughflow types, while some are connected to the river through a single channel in which water rises and falls with changing river levels. The water flow path of the latter types is best classified as bidirectional-nontidal.

  1. Wetland is not subject to lake influences.        3
  2. Wetland is formed by paludification processes where in areas of low evapotranspiration and high rainfall, peat moss moves uphill creating wetlands on hillslopes (i.e., wetland develops upslope of primary water source)..................................................................................Paludified 3.  Wetland is not formed by paludification processes.        4
  3. Wetland receives surface or ground water from a stream, other waterbody or wetland (i.e., at a higher elevation) and surface or ground water passes through the subject wetland to a stream, another wetland, or other waterbody at a lower elevation; a flow-through


system....Throughflow, Throughflow-intermittent*, Throughflow-entrenched*, or

Throughflow-artificial*


Modifiers: Groundwater-dominated throughflow wetlands can be separated from Surface water-dominated throughflow wetlands.


*Note: Throughflow-intermittent is to be used with throughflow wetlands along intermittent streams; Throughflow-entrenched indicates that stream flow is through a wetland but the stream is deeply cut and does not overflow into the wetland (therefore the stream is, for practical purposes, separate from the wetland) - this water flow path is intended to be used with Terrene wetlands in this situation; Throughflow-artificial is used to designate wetlands where throughflow is human-caused - usually to indicate connection of Terrene wetlands to other Terrene wetlands and waters by ditches and not by streams either natural or channelized


  1. Water does not pass through this wetland to other wetlands or waters.        5


  1. There is no surface or groundwater inflow from a stream, other waterbody, or wetland (i.e., no documented surface or ground water inflow from a wetland or other waterbody at a higher elevation) and no observable or known outflow of surface or ground water to other wetlands or waters...............................................................................................................................Isolated


Attention: In most applications, isolation is interpreted as "geographically isolated" since groundwater connections are typically unknown for specific wetlands. For practical purposes then," isolated" means no obvious surface water connection to other wetlands and waters. If hydrologic data exist for a locale that documents groundwater linkages, such wetlands should be identified as either outflow. inflow, or throughflow with a "Groundwater-dominated" modifier and not be identified as isolated unless the whole network of wetlands is not connected to a stream or river.  In the latter case, the network is a collection of interconnected isolated wetlands.


  1. Wetland is not hydrologically or geographically isolated.        6


  1. Wetland receives surface or ground water inflow from a wetland or other waterbody (perennial or intermittent) at a higher elevation and there is no observable or known significant outflow of surface or ground water to a stream, wetland or waterbody at a lower elevation

...........................................................................................................................................Inflow


Modifiers: Groundwater-dominated inflow wetlands can be separated from Surface water-dominated inflow wetlands; Human-caused (usually to indicate connection of Terrene wetlands to other Terrene wetlands and waters [e.g., Inflow human-caused] by ditches and not by streams either natural or channelized).


6. Wetland receives no surface or ground water inflow from a wetland or permanent waterbody at a higher elevation (may receive flow from intermittent streams only) and surface or ground


water is discharged from this wetland to a stream, wetland, or other waterbody at a lower elevation.......................................................................................Outflow or Outflow-artificial*


Modifiers: Groundwater-dominated outflow wetlands can be separated from Surface water-dominated outflow wetlands. Might consider separating perennial outflow (Outflow-perennial) from intermitttent outflow (Outflow-intermittent), if interested.


*Note: Outflow-artificial is usually used to indicate outflow from formerly isolated wetlands resulting by ditches.


    1. Occurs along a coastal river or along an island in a river................River Fringe Wetland or River Island Fringe Wetland

c. Occurs elsewhere.........................................................................................................d


    1. Occurs along an oceanic island...........................................Ocean Island Fringe Wetland

d. Occurs along the shores of exposed rocky mainland...............Headland Fringe Wetland


2. Wetland is separated from main body of marsh by natural or artificial means; the former may be connected by a tidal stream extending through the upland or by washover channels (e.g., estuarine intertidal swales), whereas the latter occurs in an artificial impoundment or behind a road or railroad embankment where tidal flow is at least somewhat restricted........Basin Wetland

Go to Key D-1 for water flow path


Modifiers may be applied to separate natural from created basins (managed fish and wildlife areas; aquaculture impoundments; salt hay diked lands; tidally restricted-road, and tidally restricted-railroad), and for other situations, as needed.


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