Assessment of Mercury in Sediments and Waters of Grubers Grove Bay, Wisconsin

Open-File Report 2022-1051
Prepared in cooperation with U.S. Army Environmental Command
By: , and 



Mercury is a global contaminant that can be detrimental to wildlife and human health. Anthropogenic emissions and point sources are primarily responsible for elevated mercury concentrations in sediments and waters. Mercury can physically move and chemically transform in the environment, resulting in biomagnification of mercury, in the form of methylmercury, in the food web and causing elevated mercury concentrations in upper trophic levels. The ability to measure total mercury concentrations in the environment has existed for several decades and makes it possible to detect hotspots that might exist because of ongoing or previous anthropogenic activity. However, recent (within the past 15 years) developments in mass spectrometry have made it possible to complete low level stable isotope analysis allowing for the determination of mercury sources—natural and anthropogenic—in the environment through “fingerprinting.” Grubers Grove Bay in Lake Wisconsin, the focus area of this study, was determined to have elevated mercury levels even after multiple remediation efforts, resulting in its listing on the Federal list of impaired waters pursuant to the Clean Water Act. Adjacent to the bay is the former Badger Army Ammunition Plant, which manufactured ammunition for the U.S. Army during the early and middle 20th century, after which it was put on standby before being fully decommissioned. This study assesses mercury concentrations in the sediments and suspended particulate matter of Grubers Grove Bay, Wiegands Bay, and upstream sites, and in adjacent soils on the former Badger Army Ammunition Plant site. This study confirmed that mercury contamination exists in the sediments of Grubers Grove Bay even after dredging attempts by the U.S. Army. Additionally, using isotope ratios and a two-endmember mixing model, it was determined that soil from within Badger Army Ammunition Plant’s former site contributed a substantial amount of mercury to the bay. This result was supported by an observed gradient of high to low mercury concentrations from the innermost (nearest Badger Army Ammunition Plant) to the outermost (farthest from Badger Army Ammunition Plant) part of the bay.

Suggested Citation

Routhier, E.J., Janssen, S.E., Tate, M.T., Ogorek, J.M., DeWild, J.F., and Krabbenhoft, D.P., 2022, Assessment of mercury in sediments and waters of Grubers Grove Bay, Wisconsin: U.S. Geological Survey Open-File Report 2022–1051, 20 p.,

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Acknowledgments
  • Abstract
  • Introduction
  • Methods
  • Results
  • Discussion
  • References Cited
  • Glossary
  • Appendix 1. Suspended Particulate Matter Total Mercury and Methylmercury Data
  • Appendix 2. Sediment and Soil Methylmercury Data
  • Appendix 3. Isotope Quality Assurance Results
Publication type Report
Publication Subtype USGS Numbered Series
Title Assessment of mercury in sediments and waters of Grubers Grove Bay, Wisconsin
Series title Open-File Report
Series number 2022-1051
DOI 10.3133/ofr20221051
Year Published 2022
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Wisconsin Water Science Center, Upper Midwest Water Science Center
Description Report: vii, 20 p.; Data release
Country United States
State Wisconsin
Other Geospatial Grubers Grove Bay
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details