The HHPLS identified the infiltration potential of the upland areas within the subwatershed as medium to low with some areas of variability where the soils are organic in nature (see Figure 16). A few areas of high infiltration potential are located in sandy till areas. Areas of moderate to high or very high aquifer sensitivity roughly follow the two tributary/wetland corridors in the upper subwatershed and the Long Lake Creek corridor to Browns Bay. Elsewhere the Hennepin County Geologic Atlas classifies most of the upland areas as being of low to moderate sensitivity to pollution (see Figure 17).
Portions of the Long Lake subwatershed have been designated by the Minnesota Department of Health as a Drinking Water Sensitivity Management Area (DWSMA) and Wellhead Protection Area for City of Plymouth and City of Long Lake public wells. The MDH has designated much of this area to be of low risk and vulnerability to contamination of the drinking water supply, with a small area located in a till deposit being of moderate risk and vulnerability. Figure 18 shows the Wellhead Protection Areas and associated DWSMA by vulnerability risk.