2.5.6 Groundwater

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).    Areas of high aquifer sensitivity are generally related to wetlands.   There are also some areas of high sensitivity west of Piersons Lake and south of Marsh Lake, in pockets where ice- stratified deposits of gravel underlay the soil rather than the till deposits that typically underlay the subwatershed (see Figure 17). 

An area within St. Bonifacius has been designated a Wellhead Protection Area and a Drinking Water Sensitivity Management Areas (DWSMA) for a City of St. Bonifacius well.  A small area north of Stone Lake has been designated a DWSMA for a City of Minnetrista well.  The Minnesota Department of Health has designated these areas to be of low risk and vulnerability to contamination of the drinking water supply.  Figure 18 shows the DWSMAs and associated Wellhead Protection Areas.

The County Well Index has records of approximately 215 wells in the subwatershed, mostly shallow (less than 300 feet deep) domestic water supply wells and about six deeper, municipal wells.