WU represents the wetland/upland complex.  This mapping unit indicates that wetlands and uplands are present, but at a scale too fine to map separately at the scale of 1:25,000.  It can occur with any wetland Ecosystem.  The wetland proportion exceeds at least 30%.

WUs are not numerous but can be extensive.  The are usually forested, often found at edges the terraced moraines fronting the western slope of the Caribou Hills, the edges of high elevation Late Snow Plateaus or at the edge of the interlobate moraine along the coast north of Nikiski.  Modified moraines with plenty of surface relief typify all of these locations.  High spots are upland with wetlands in low spots, too small to delineate at 1:25,000. 

Some areas mapped as WU lack heterogeneous surface relief, but have ambiguous wetland character.  The water table may be very near 30 cm (one foot) below the surface, coming closer in some spots than others, or the peat layer may be 41 cm thick in some spots and 38 cm in others, barely qualifying as a jurisdictional wetland.  Accurate wetland delineation at a practical scale is difficult in many WU areas.