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RiparianDEMRiparian Ecosystem wetlands are rivers and streams and their adjacent valley bottoms. Rosgen's stream classification system is employed, with some modification. In Rosgen's system streams are classified using channel and valley forms, among other characters. In the area mapped stream reaches are largely E streams, those formed on sediments laid down by other, larger processes. In the MAT-SU Valley these processes are associated with the maximum extent of glacial ice during the last advance. E streams are highly sinuous, pool dominated reaches in underfit valleys. E stream reaches in the valley have been classified into three types: l, s and b. Rel streams are linear E streams, Res reaches are sinuous (all of Rosgen's E streams are highly sinuous) and Reb reaches are bankfull - caused by either beaver dams, road crossings or under-sized culverts.


The Little Susitna River is a C stream, with cut banks and point bars. Wasilla Creek has many B stream reaches, where a riffle and pool structure dominates. Vine, or Phantom Creek exhibits B stream character, but is an unclassified different type because it does not connect at the surface to Cook Inlet. It is the creek that heads in a wetland south of Memory Lake, and disappears into gravels just west of Vine Road.

Adjacent valley bottoms often support uplands. Although they are not considered wetlands for regulatory purposes, these location ns will eventually flood as the channel migrates across the valley floor.

Table 1. Riparian Ecosystem Wetlands
Peat Depth (n=5)
Water Table (n=7)
Redox features (n=1)
Saturation (n=6)
pH (n= 22)
Specific Conductance (25°C; n=22)
Plant Prevalence Index (n=5)
121 cm
-5 cm
148 cm
11 cm
180.0 µS


Peat depth is a minimum, because some sites had thicker peat deposits than the length of the auger used (usually 493 cm).

Water table depth is a one time measurement. Negative numbers indicate a water table above the surface. At sites with seasonally variable water tables this measurement reflects both the conditions that year, and the time of year.

Redox features with low n and deep depths typically indicate deeper peat deposits, which mask redox indicators.

pH and specific conductance measured in surface water or a shallow pit with a YSI 63 meter calibrated each sample.

Plant Pre valance Index calculated based on Alaska indicator status downloaded from the USDA PLANTS database, which may use different values than the 1988 list.




Black spruce / Thinleaf alder

Water sedge - marsh fivefinger

Paper birch / prickly rose / field horsetail

Thinleaf alder / bluejoint reedgrass


Soils from 1998 Soil Survey of the Matanuska-Susitna Valley Area, Alaska, available online, follow the link in the table heading.

Plant communities based on Kenai Peninsula wetland mapping and soil survey, or other published accounts, especially Viereck, et.al., 1992.


Spring Fen Ecosystem Wetland Map Components:

SF1: Spring Fen Ponds.

SF2: Spring Fens with water table near the surface. Often dominated by creeping sedge, marsh cinquefoil, and/or bluejoint reedgrass.

SF3: Spring Fens dominated by shrubs, especially thinleaf alder and dwarf birch.

SF4: Spring fens with deeper fluctuating water table, forested.

Map Units currently in use: SF1, SF1-3, SF1-4, SF12, SF1c, SF2, SF2-4, SF21, SF21d, SF23, SF23C, D23d, SF24d, SF2c, SF2d, SF3, SF31, SF32, SF34, SF34d, SF3d, SF4, SF42, SF43.



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Kenai Watershed Forum
PO Box 15301
Fritz Creek, AK 99603
2 April, 2009

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