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.i ,-AA--,' ''Abl-_-• 4 =f ' -,=,-• 9 n ° `°' ' r r; 7 ';-::,,l',#::- 1; ir. -- '4.- ;‘, :li:6i.it: , r It v4 ♦ Figure 3.Aerial photos of Harbison Creek,from left to right,in 2010,1980,1955,and 1937.Historical aerial photos of the stream indicate no appreciable lateral shifts in the stream or pond. Existing Conditions Existing Vegetation The study site vegetation includes a variety of grasses, sedges,herbaceous species, shrubs, and trees.Many of the species surrounding Harbison Creek are native to wet meadow and upland ecotones. The native species include a number of black willow, green ash,and walnut trees. Box elder is well established on the berm surrounding the pond. Floodplain vegetation includes jewelweed,nettle,joe pye weed, goldenrod, sedge species, and grapes. Red osier dogwood and high bush cranberry are also found onsite. Within the channel, abundant water cress indicates significan t groundwater inputs, and is considered a high value species that promotes the presence of stream macroinvertebrates and provides cover for fishes. A number of non-native species are also present;these include extensive monocultures of reed canary grass,patches of Canada thistle, and buckthorn upstream of the pond. Geology The majority of the Harbison Creek watershed is underlain by subglacial till complex typical of Northeastern Dane County(Figure 4). The gravely, clayey, silty sand till was deposited during the last Wisconsin Glaciation by the Green Bay Lobe, approximately 15,000 to 20,000 years ago. This Pleistocene (Horicon Member;gs-Figure 4) till ranges from 1 to 20 feet deep (Clayton et al., 1997), and overlies Cambrian Tunnel City group sandstone. The southern portion of Harbison Creek and the pond lies atop silty and sandy lake sediment deposited along the shore of an expanded Lake Mendota (og—Figure 4). Some finer floodplain sediment associated with Token Creek(sm) is deposited at the confluence of Harbison Creek and the larger channel. 3