T6DW3 is a mixture of the Lyngbye's sedge Tidal Ecosystem map component (T6) with the hummocky shrubby Relict Glacial Drainageway Ecosystem component (DW3). The only wetlands with mixed ecosystem names are found in the upper reaches of the tidally influenced zone. 

T6 and DW3 mix in one location, represented by four polygons, near the Warren Ames Memorial Bridge over the Kenai River, at about river mile 4.  The single DW3T6 unit is the largest and occupies most of the inside river bend between river miles 5 and 7.5.

The Lyngbye's sedge component (T6), corresponds with Vince and Snow's (1984) 'Inner Sedge Marsh Zone 7', estimated to be inundated on only the highest spring tides, or an average of 2 times per summer on the Susitna Flats (with a range of 0-5 times per summer). 

Sweetgale (Myrica gale) is often the first shrub to dominate wetlands just above tidal influence, and it dominates the DW3 component.  Sweetgale forms a hummocky peatland with dwarf birch (Betula nana) and fewflower sedge (Carex pluriflora), another common upper-tidal-influence plant.

In the large DW3T6 wetland, Lyngbye's sedge (T6) forms small, more or less segregated patches in micro-topographic low spots within a larger hummocky shrubby Relict Glacial Drainageway (DW3) matrix.  In the smaller T6DW3 wetlands, the drainageway component is more or less mixed in with the Lyngbye's sedge component.