Wellhead Protection Area (WHPA)
A designated zone around a public water supply well where contamination poses a direct threat to drinking water quality.
A Wellhead Protection Area (WHPA) is the surface and subsurface area surrounding a water well or well field that supplies a public water system, through which contaminants are reasonably likely to move toward and reach the well. WHPAs are delineated based on hydrogeological analysis of groundwater flow patterns, aquifer characteristics, and pumping rates.
UST facilities and LUST release sites located within WHPAs are of particular concern because contamination from these sources could directly impact public drinking water supplies. The EPA's UST database tracks whether each facility falls within a WHPA, providing a critical risk factor for environmental assessment and prioritization.
States implement Wellhead Protection Programs under the Safe Drinking Water Act to prevent contamination of public water supplies. These programs may impose additional restrictions on UST operations within WHPAs, including enhanced monitoring requirements, stricter closure standards, and expedited cleanup timelines for any detected releases.
Related Terms
The area from which a public water system draws its drinking water, where contamination prevention is critical.
Groundwater ContaminationThe pollution of underground water sources by petroleum products or hazardous substances from leaking USTs or other sources.
Underground Storage Tank (UST)A tank and connected piping with at least 10% of volume underground, used for storing petroleum or hazardous substances.
RemediationThe process of cleaning up contaminated soil, groundwater, or other environmental media at a LUST or hazardous waste site.