Wetland Classification and Mapping of the Kenai Lowland, Alaska





Map Unit Descriptions



Ecosystem: Riparian


Map Unit: Res


Extent: 53 wetland polygons; 2294.8 ha; 1.62% of wetland area; 0.32% of wetland polygons.

An Res reach on an RDA tributary to Starisky Creek  (polygon 2904).

Wetland Indicators

Type: Stream

Average depth to water table: 54.4 cm; n=18

Organic layer thickness: 23.1 cm; n=16

Average depth to redoximorphic features: 28.0 cm; n=9


Common Plant communities:

Barclay willow / Bluejoint - Field horsetail

Bluejoint streamside

Barclay Willow / Bluejoint

Barclay willow / Bluejoint / Marsh fivefinger

Lutz spruce / Barclay willow / Field horsetail / Crowberry


NWI: Stream: R2US3,4.  Valley wetlands: PSS1/EM1Jg

HGM: Stream: Low Gradient Natural Straight Stream-single thread.  Valley wetlands: Lotic Slope/Flat groundwater-dominated Throughflow/Bidirectional-nontidal.

Accuracy assessment: 14 polygons interpreted as Res on aerial photographs were field checked.  11 remained Res; 1 each was revised to: RDA, Rel and RB.


Res units are in Rosgen's (1996) E stream category.  E streams are slightly entrenched, low-gradient, pool-dominated sluggish streams with thickly vegetated banks.  They occur on surfaces deposited by larger processes.  On the Kenai Lowlands, those larger processes occurred when glaciers occupied more of the landscape during the last major advance and then left behind lakebed, drainageway and kettle surfaces. 

Res units are E streams with sinuous channels (with sinuosity greater than 1.3).  E streams are the most common streams on the lowlands;  typical Rosgen E streams have high channel sinuosity, but many Kenai Lowland E streams have a sinuosity of less than 1.3 (usually around 1.1).  Res units often occur as underfit streams flowing through peatlands on relict glacial drainageways.  Streambed material is typically cobbles (Rosgen's E3), or gravels (E4).

Res streams frequently have an extensive wetland fringe, as they often occupy relict glacial surfaces which support large peatland complexes. 

After the floods that occurred during October and November of 2002, many E streams' character changed.  Their beds were scoured, creating more riffles, and exposing cobbles and gravels.  Beaver dams breached, so E streams that were dammed became free-flowing and now exhibit some B and C stream characters. 

E streams are considered "evolutionary" (Rosgen, 1996).  Many of these steams should probably be re-examined to observe whether or not they: 1) changed during the floods, 2) return to their former character, or 3) begin to evolve into a different stream type.  The floods may have been one of the first big episodes in the long term evolution of these streams.  The glacial till these streams now flow across will eventually be left as a terrace as the stream valley becomes entrenched into underlying bedrock over time.  Then the till terrace will erode into the stream, a deep V-shaped valley will form, then perhaps glaciers will return and reset the process.


Fifty foot habitat protection area

Fourteen streams in the project area are covered under Kenai Peninsula Borough's Anadromous Streams Habitat Protection Ordinance.  Many activities require a permit, or are prohibited within 50 feet of these streams.  For a list of the streams, rationale for the ordinance, and details on obtaining a permit, visit the link highlighted above.


Floodplain regulation

From The Kenai Borough website:

"The Kenai Peninsula Borough manages a Floodplain Ordinance that addresses proper development to reduce flood risks and lessen the economic losses caused by flood events. The ordinance provides building standards for construction projects within the floodplain to ensure the availability of flood insurance through the National Flood Insurance Program. These building requirements also are intended to minimize or prevent damage when flood events occur. The ordinance requires floodplain development permits for all projects in floodplains."

Do I Need a Permit?

 Introduction and Key to Plant Communities  

Introduction and Key to Ecosystems

    Kenai Hydric Soils    Map Unit Summary    Methods    Glossary


Contact: Mike Gracz
Kenai Watershed Forum 
Homer Field Office
Old Town Professional Center
3430 Main Street Suite B1
Homer, AK  99603

15 November 2005 15:04