EPA Superfund site
MOSES LAKE WELLFIELD CONTAMINATION
Exposure status: insufficient data
Data limitations: Proximity to a Superfund site boundary does not mean your property is contaminated. EPA site boundaries show the area designated for cleanup, not the full extent of contamination. Groundwater plumes can extend beyond site boundaries. This tool shows publicly available EPA federal data. It is not affiliated with or endorsed by EPA, and is not a substitute for a professional environmental assessment.
About this site's exposure pathways
As of July 2026, the Moses Lake Wellfield Contamination Superfund (Site) is considered “Insufficient Data to make a Human Exposure evaluation” (HEID) because it has not been determined if per- and polyfluoroalkyl substances (PFAS) are present in residential drinking wells. The contaminants of concern for soil at the Site are polychlorinated biphenyls, petroleum hydrocarbons, trichloroethylene (TCE), arsenic, lead, and mercury. The contaminant of concern for groundwater at the Site is TCE. Currently, there are no exceedances above EPA’s maximum contaminant levels of TCE in private drinking water wells. Perfluorohexanesulfonic acid, perfluorononanoic acid, perfluorooctane sulfonic acid and perfluorooctane acid are present and above EPA’s maximum contaminant level in monitoring wells at 6 isolated locations within the wellfield area. Sampling in private residential wells used for drinking water have not been tested for PFAS to date. The planned activities to collect sufficient information to evaluate Human Exposure control status are groundwater sampling for PFAS and continued monitoring of TCE in private wells. EPA is currently determining strategic sampling locations at private residential wells to better understand PFAS contamination in groundwater and understand risk. EPA currently anticipates that there will be sufficient data to make a Human Exposure evaluation by 2030. In addition, EPA will continue to conduct annual groundwater sampling for TCE at private wells throughout the site and install water filtration systems in homes with TCE levels at or above 3.5 ug/L. EPA continues to implement an institution control (IC) plan to ensure that new or expanded drinking water systems and private wells do not inadvertently deliver TCE-contaminated groundwater for human consumption or contribute to the expansion of existing groundwater plumes. Groundwater use within the IC boundary is evaluated quarterly by reviewing of public records, including water well permits and well completion reports. If a new well is installed within the IC boundary, groundwater samples are collected to evaluate its suitability for potable use and if a whole-house filter is necessary.