The State of Michigan defines a WHPA as "the surface and subsurface areas surrounding a water well, or well field, which supplies a public water system, and through which contaminants are reasonably likely to move toward and reach the water well, or well field within a 10-year time of travel."

The WHPAs for the MSU campus water supply wells were delineated by the USGS as part of a regional project undertaken by the Tri-County Regional Planning Commission (TCRPC). In 1991, the TCRPC began studies to assess the regional water supply and distribution system. As part of this effort, the USGS entered into a cooperative agreement with the TCRPC and a coalition of 22 communities, who supported a 4 year study of groundwater flow and contribution areas of public supply wells in the Tri-County region. During this process, the USGS developed a regional numerical groundwater flow model for the area using the MODFLOW code.

Additional work was performed by the USGS to more accurately delineate the WHPAs in the Tri-County area. This work involved making slight modifications to the MODFLOW model and delineating 10-year time of travel areas for the WHPAs.

The USGS identified WHPAs in the Tri-County area using particle-tracking techniques. Particles were traced backward from the wells until they reached the top cell face in the upper layer and then projected up to the land surface. The areas where the particles reached the surface were identified as areas of contribution. Areas between the wells and the areas of contribution were considered areas of transport.

MSU and its consultant refined the work by updating well locations and pumping rates. As old wells are removed from service and new wells are brought online, delineations are updated. The latest WHPA delineation was completed and approved in 2014.