Wisconsin State Agency Recommends Stringent Groundwater Standard for Hexavalent Chromium

The Wisconsin Groundwater Coordinating Council (comprised of representatives from several state agencies, the Governor’s office and universities) prepares an annual report that summarizes the operations and activities of the council, describes the state of the groundwater resource and its management and makes recommendations.  In the 2021 Wisconsin Groundwater Coordinating Council Report to the Legislature, the naturally-occurring chromium in groundwater was referenced.  The report noted that “[a]s water flows underground, metals such as chromium, may be dissolved from rock or soil and be mobilized, and therefore present in groundwater.  Natural sources of chromium in groundwater include some types of igneous bedrock and soils derived from those bedrock sources.”

While both trivalent chromium and hexavalent chromium are found in groundwater, in Wisconsin water quality analysis for chromium is generally done for “total chromium.”  The US EPA has established a public water supply MCL for total chromium at 100 micrograms per liter (μg/L) and, in Wisconsin, the groundwater quality enforcement standard for total chromium is also 100 μg/L.  

The Wisconsin Department of Natural Resources (DNR) Remediation and Redevelopment program requested a health-based groundwater standard for hexavalent chromium.  The Wisconsin Department of Health Services (DHS) recently recommended a groundwater quality enforcement standard of 70 nanograms per liter (ng/L) and a preventive action limit (PAL) of 7 ng/L for hexavalent chromium based on its potential to cause cancer.  DHS must identify the health-based level at the estimated cancer risk of one in one million for a person with body weight of 177 pounds.  The PAL is then set at ten percent of the enforcement standard as required by state statute.  The scientific Support Documents for this recommended standard is available on the DHS website at:  https://www.dhs.wisconsin.gov/publications/p02434v.pdf.  

Wisconsin has issued a white paper for rule development for this stringent groundwater standard, and has requested comments on the white paper.  This recommended level for hexavalent chromium is several orders of magnitude more stringent that the existing standard for total chromium. and could have a significant impact on the monitoring, control and remediation of groundwater in Wisconsin.  If you have any questions or would like additional information on this issue, please contact Jeff Hannapel with NASF at crichter#@thepolicygroup.com or jhannapel@thepolicygroup.com.  

This update is courtesy of the National Association for Surface Finishing (NASF). For more information or to become a member, visit nasf.org.