Significant acreage in the watershed is woodland. Away from the Wisconsin River floodplain there are few wetlands, mostly wet meadows which are grazed or cultivated adjacent streams. There are large wetland complexes along the Wisconsin River particularly near Avoca, which are very important for wildlife. The portion of the watershed on the Wisconsin River floodplain is also in an atrazine management area. Elevated levels of atrazine, a herbicide used on corn, has been found in some tested private water wells.
Soils are permeable, which allows atrazine to reach groundwater in some locations.
Avoca and Highland have Wisconsin Pollutant Discharge Elimination System-permitted discharges to groundwater in the watershed. Avoca is considering the possibility of a surface water discharge to Morrey Creek. Streams of the Watershed Harker Creek Harker Creek is a tributary to Otter Creek below Blackhawk Lake. The stream has a steeper gradient than Otter Creek. Otter Creek Otter Creek is a tributary to the Wisconsin River.