Key A-1: Key to Wetland Landscape Position


This key allows characterization of wetlands based on their location in or along a waterbody, in a drainageway, or in isolation ("geographically isolated" - surrounded by upland).


    1. Wetland is completely surrounded by upland (non-hydric soils)....................................Terrene
  1. Wetland is not surrounded by upland but is connected to a waterbody of some kind.        2
  2. Wetland is located in or along tidal salt or brackish waters (i.e., an estuary or ocean) including its periodically inundated shoreline (excluding areas formerly under tidal influence).        3
  1. Wetland is not periodically inundated by salt or brackish tides.        4


3. Wetland is located in or along the ocean........................................................................Marine

Go to Key C-1 for coastal landform

  1. Wetland is located in or along an estuary (typically a semi-enclosed basin or tidal river where fresh water mixes with sea water)..................................................................................Estuarine

Go to Key E-2 for Estuary Type, then to Key C-1 for coastal landform


Note: If area was formerly connected to an estuary but now is completely cut-off from tidal flow, consider as one of inland landscape positions - Terrene, Lentic, or Lotic, depending on current site characteristics. Such areas should be designated with a modifier to identify such wetlands as "former estuarine wetland." Lands overflowed infrequently by tides such as overwash areas on barrier islands are considered Estuarine. Tidal freshwater wetlands contiguous to salt/brackish/oligohaline tidal marshes are also considered Estuarine, whereas similar wetlands just upstream along strictly fresh tidal waters are considered Lotic.


  1. Wetland is located in or along a lake or reservoir (permanent waterbody where standing water is typically much deeper than 6.6 feet at low water), including streamside wetlands in a lake basin and wetlands behind barrier islands and beaches with open access to a lake.............Lentic

Go to Key C-2 for Lake Type

Then Go to Key B-1 for inland landform


Note: Lentic wetlands consist of all wetlands in a lake basin (i.e., the depression containing the lake), including lakeside wetlands intersected by streams emptying into the lake. The upstream limit of lentic wetlands is defined by the upstream influence of the lake which is usually approximated by the limits of the basin within which the lake occurs. The streamside lentic wetlands are designated as "Throughflow," thereby emphasizing the stream flow through these wetlands. Other lentic wetlands are typically classified as "Bidirectional-nontidal" since water tables rise and fall with lake levels during the year.  Tidally-influenced freshwater lakes have "Bidirectional-tidal" flow.


Modifiers: Natural, Dammed River Valley, Other Dammed - see Key C-2 for others.

  1. Wetland does not occur along this type of waterbody.        5


  1. Wetland is located in a river or stream (including in-stream ponds), within its banks, or on its active floodplain and is periodically flooded by the river or stream          6
  1. Wetland is not located in a river or stream or on its active floodplain............................Terrene


Note: These wetlands may occur: (1) on a slope or flat, or in a depression (including ponds, potholes, and playas) lacking a stream but contiguous to a river or stream, (2) on a historic (inactive) floodplain, or (3) in a landscape position crossed by a stream (e.g., an entrenched stream), but where the stream does not periodically inundate the wetland.

Go to Key B-1 for inland landform


  1. Wetland is the source of a river or stream but this watercourse does not extend through the wetland.............................................................................................................................Terrene


Modifiers: May include Headwater for wetlands that are sources of streams and Estuarine Discharge or Marine Discharge for wetlands whose outflow goes directly to an estuary or the ocean, respectively.

  1. Wetland is located in a river or stream, within its banks, or on its active floodplain.        7


  1. Wetland is associated with a river (a broad channel mapped as a polygon or 2-lined watercourse on a 1:24,000 U.S. Geological Survey topographic map) or its active floodplain........

...................................................................................................................................Lotic River

Go to Couplet "a" below (Also see note under first couplet #3 - Lentic re: streamside wetlands in lake basins)


  1. Wetland is associated with a stream (a.linear or single-line watercourse on a 1:24,000 U.S. Geological Survey topographic map) or its active floodplain....................................Lotic Stream

Go to Couplet "a" below (Also see note under first couplet #3 - Lentic re: streamside wetlands in lake basins)


Note: Artificial drainageways (i.e., ditches) are not considered part of the Lotic classification, whereas channelized streams are part of the Lotic landscape position.


Modifiers: Headwater (wetlands along first-order streams and possibly second-order streams and large wetlands in upper portion of watershed believed to be significant groundwater discharge sites) and Channelized (excavated stream course).


    1. Water flow is under tidal influence (freshwater tidal wetlands)..............Tidal Gradient

Go to Key B-1 for inland landform

a. Water flow is not under tidal influence (nontidal)..........................................................b


    1. Water flow is dammed, yet still flowing downstream, at least seasonally........................

................................................................................................................Dammed Reach

Go to Key B-1 for inland landform Modifiers: Lock and Dammed, Run-of-River Dam, Beaver Dam, and Other Dam (see Waterbody Key B-2 for further information).


b. Water flow is unrestricted.............................................................................................c


    1. Water flow is intermittent during the year...................................Intermittent Gradient

Go to Key B-1 for inland landform

c.  Water flow is perennial (year-round)............................................................................d


    1. Water flow is generally rapid due to steep gradient; typically little or no floodplain development; watercourse is generally shallow with rock, cobbles, or gravel bottoms; first- and second-order "streams" in hilly to mountainous terrain; part of Cowardin's Upper Perennial Subsystem..........................................................................High Gradient

Go to Key B-1 for inland landform

  1. Watercourse characteristics are not so; "stream" order greater than 2 in hilly to mountainous terrain..........................................................................................................e


  1. Water flow is generally slow; typically with extensive floodplain; water course shallow or deep with mud or sand bottoms; typically fifth and higher order "streams", but includes lower order streams in nearly level landscapes such as the Great Lakes Plain (former glacial lakebed) and the Coastal Plain, and ditches; the lower order streams may lack significant floodplain development); Cowardin's Lower Perennial subsystem.....................

...................................................................................................................Low Gradient

Go to Key B-1 for inland landform

e. Water flow is fast to moderate; with little to some floodplain; usually third-, fourth- and higher order "streams" associated with hilly to mountainous terrain; part of Cowardin's Upper Perennial Subsystem...................................................Middle Gradient

Go to Key B-1 for inland landform


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