Long-Term Hydrologic Sustainability of Calcareous Fens along the Glacial Lake Agassiz Beach Ridges, Northwestern Minnesota, USA

Nicholas R. Budde, Howard D. Mooers, Timothy K. Cowdery, Nigel J. Wattrus

Research output: Contribution to journalArticlepeer-review

Abstract

Calcareous fens are peat-accumulating wetlands fed by calcium-rich groundwater that support several threatened species of plants that thrive in these geochemical conditions. This investigation characterized the hydrology of two calcareous fens in the Glacial Lake Agassiz beach ridge complex in northwestern Minnesota, USA. Sandy surficial beach ridge aquifers and underlying buried glacial aquifers were considered as sources of groundwater to the fen. A combination of the two sources influenced by seasonal hydrology was also considered. Synchronous hydrologic responses to rainfall events and hydraulic gradients indicate the calcareous fens are well-connected to the beach-ridge aquifers. Chemistry of water discharging to the fens is calcium-magnesium-bicarbonate type similar to the beach ridge aquifers, and distinct from buried aquifers that have significant sodium and chloride. High tritium values and oxygen isotope signatures similar to the beach ridge aquifers characterized fen water. Beach ridge aquifer complexes are relatively thin (8–10 m) and overlie thick clay/clay loam till. These beach ridges exhibit high seasonal recharge and have permanent saturated zones, providing a continual source of calcium-rich water for the fens. Electrical resistivity profiles characterized the glacial stratigraphy and highlighted the well-developed physical connection between beach ridge aquifers and calcareous fens. The results of this study allow evaluation of the potential impacts of irrigation and aggregate quarrying on calcareous fens along sand and gravel beach ridges.

Original languageEnglish (US)
Article number28
JournalWetlands
Volume42
Issue number4
DOIs
StatePublished - Apr 2022

Bibliographical note

Funding Information:
This research was funded by the Graduate School of the University of Minnesota and by the Geology Research Fund in the Department of Earth and Environmental Sciences at the University of Minnesota Duluth. The authors would like to thank Jason Ver Steeg of Duininck Companies, Keith Chisholm, and other landowners for access to their properties for the research project. Various departments and individuals at the University of Minnesota helped provide equipment and expertise as well as laboratory services that made this project possible. This includes the co-authors, Salli Dymond, John Pastor, Nate Johnson, Julie Agnich, the College of Food, Agricultural, and Natural Resource Science?s Research Analytical Lab, and the Natural Resources Research Institute. The U.S. Geological Survey lent the pressure transducers used for this project. The Tritium Laboratory at the University of Miami donated the tritium analyses used in this project through the Geological Society of America. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the University of Minnesota or the United States Government.

Funding Information:
This research was funded by the Graduate School of the University of Minnesota and by the Geology Research Fund in the Department of Earth and Environmental Sciences at the University of Minnesota Duluth. The authors would like to thank Jason Ver Steeg of Duininck Companies, Keith Chisholm, and other landowners for access to their properties for the research project. Various departments and individuals at the University of Minnesota helped provide equipment and expertise as well as laboratory services that made this project possible. This includes the co-authors, Salli Dymond, John Pastor, Nate Johnson, Julie Agnich, the College of Food, Agricultural, and Natural Resource Science’s Research Analytical Lab, and the Natural Resources Research Institute. The U.S. Geological Survey lent the pressure transducers used for this project. The Tritium Laboratory at the University of Miami donated the tritium analyses used in this project through the Geological Society of America. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the University of Minnesota or the United States Government.

Funding Information:
This project was supported with funds from the University of Minnesota Graduate School and the Geology Research Fund in the Department of Earth and Environmental Sciences, University of Minnesota Duluth.

Publisher Copyright:
© 2022, The Author(s), under exclusive licence to Society of Wetland Scientists.

Keywords

  • Calcareous fen
  • Glacial Lake Agassiz
  • Hydrology
  • Minnesota
  • Water chemistry

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