Michigan Dept. of Environment, Great Lakes, and EnergyWellhead protection areas represent the land surface area that contributes ground water to wells serving public water supply systems throughout Michigan. The areas define a landscape in which management strategies are employed to protect public water supply wells from ground water contamination. This dataset is just community WHPAs, defined as Type I water supplies. It does not include WHPAs for Type II water supplies (noncommunity transient or non-transient supplies). Wellhead Protection Areas in the dataset are categorized as traditional, provisional, and low vulnerability. The categories are used to describe how the wellhead protection area was identified. A traditional wellhead protection area is established by a hydrogeologic study. A hydrogeologic study includes an initial compiling of readily available information, the completion of fieldwork to obtain a better understanding of the hydrogeologic system, and groundwater modeling to identify the WHPA. Available information is normally sufficient to develop a rudimentary conceptualization of the hydrogeologic system and identify areas requiring additional acquisition of information and data. Fieldwork is completed to fill voids in the available information, confirm or modify the rudimentary conceptualization, and provide the information base necessary for groundwater flow modeling to delineate the WHPA. The available information and information collected through fieldwork is used to develop a final conceptualization of the hydrogeologic system. The final hydrogeologic conceptualization is incorporated into a groundwater flow model that is used to identify the WHPA. There are three widely accepted approaches for delineation of a WHPA. The three approaches reflect an increase in the amount of fieldwork, an increase in the level of complexity of the groundwater flow model, or both. The approaches will be referred to as follows: 1. Confirmation of Existing Information, 2. Direct Determination of Groundwater Flow Direction and Hydraulic Gradient, 3. Extensive Hydrogeologic Investigations. A common denominator to the three approaches is the use of "reverse particle tracking" to identify the WHPA. Particle tracking may be described as "tracing the movement of an imaginary groundwater particle on the groundwater potentiometric surface." Thus, particle tracking identifies the path which groundwater takes in moving from areas of high energy to areas of low energy. In WHPA delineations it is more practical to perform the tracing of groundwater movement in reverse, or reverse particle tracking. Reverse particle tracking traces the movement of groundwater from areas of low energy to areas of high energy (i.e., from the pumping well back to the area of recharge). Reverse particle tracking eliminates the "trial-and-error" associated with forward particle tracking by eliminating areas of the potentiometric surface from which groundwater would not migrate to the well. With any of these three delineation approaches, there must be an appropriate aquifer test conducted for the water supply well. If there is not a test which meets the requirements of Aquifer Test Requirements for Public Water Supply Wells, an appropriate aquifer test will need to be performed. A provisional wellhead protection area is an area which has been approved by the department in accordance with the State of Michigan wellhead protection program as the wellhead protection area based on computer manipulation of existing state of Michigan databases. A low vulnerability wellhead protection area is one that is defined by having low tritium concentrations indicating the source water pre-dates nuclear weapons testing in the 1950s and 1960s. The traditional WHPAs and any updates are typically submitted by consultants who work for community water supplies. The WHPAs and updates are added to the system through GIS georeferencing and digitization as they are submitted and approved by the Department. The provisional wellhead delineations were completed by EGLE staff using MGMT groundwater modeling software program. The provisional WHPAs were created prior to 2013. Field Name Description AREA Area of the WHPA in square miles WSSN Water Supply Serial Number SYSTEM Water Supply System Name TYPE Provisional or Traditional WHPA APPROVAL_DATE Date WHPA approved by EGLEArcGIS DynamicMapLayerhttps://hub.arcgis.com/datasets/868e2d670a2641d48e0b150a84769e18_0engState of Michigan Open Data PortalPublicWellhead Protection Areas (WHPA) [Michigan]Web servicesMichiganLast Modified: 2025-09-24