Matanuska-Susitna Wetland Mapping

Cook Inlet Wetlands

DRAINAGEWAY  ECOSYSTEM Wetlands

A 2004 satellite photo showing a Relict Glacial Drainageway Ecosystem wetland (oorange tones) between Wasilla and Knk Arm.

Relict Glacial Drainageway wetlands are peatlands occupying relict, sometimes abandoned, drainageway features. These are linear features which drained once more extensive glaciers. Some may have formed along glacier margins. Some support modern streams but these streams are underfit. Many are now filled with peat. These peatlands are fens, with a stable high water table supported by ample groundwater throughflow that has had recent contact with mineral substrates.

A Relict Glacial Drainageway draining into Threemile Lake.

Explanation:

All data from wetlands throughout the Cook Inlet Lowlands, not just from the Matanuska-Susitna Valley.

Numbers in paraentheses indicate number of samples.

Peat depth is a minimum, because some sites had thicker peat deposits than the length of the auger used (between 160 - 493 cm).

Water table depth is a one time measurement. At sites with seasonally variable water tables this measurement reflects both the conditions that year, and the time of year. If no water table was encountered, no value was recorded; use number of samples to aid interpretation.

Redox features with deep depths typically indicate deeper peat deposits, which mask redox indicators so the depth corresponds to the peat thickness.

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

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

DRAINAGEWAY Ecosystem Wetland Map Components:

Map unit names are made of combinations of map components. A suffix 'c' idicates a created wetland, and a 'd' indicates a highly disturbed wetland.

DW1: Ponds in Drainageways.

DW2: Drainageways with water table near the surface most of the growing season. Often dominated by sedges, dwarf birch and/or sweetgale.

DW3: Drainageways often dominated by medium-height shrubs.

DW4: Drainageways dominated by Bluejoint reedgrass (Calamagrostis canadensis).

DW5: Draingeway margins dominated by thick Sphagnum moss, and often black spruce forests.

DW5A: Forested Drainageways.