Hydrologic Controls on the Extent of the Kasota 7 Calcareous Fen, Le Sueur County, Minnesota
Presented on Monday, May 5, 2014
Matthew Uliana1, Aaron Weegar1, Jamie Swenson2 and Doug Losee3, (1)Weegar-Eide & Associates, LLC, Austin, TX, (2)I&S Group, Inc., Mankato, MN, (3)UNIMIN Corporation, Mankato, MN
Calcareous fens are defined as ground- and surface-water supported wetlands that contain a plant assemblage dominated by calciphilic (i.e., “calcium-loving”) plant indicator species. These fens are also defined by a set of criteria that include continuous groundwater discharge that is sufficient to maintain soil saturation, histosol soils containing a significant fraction of calcium carbonate minerals, and various water quality parameters.
The Kasota 7 calcareous fen is a legally protected wetland area located in Le Sueur County, Minnesota, in the floodplain of the Minnesota River. Geochemical and head data indicate that fen waters are derived from about 35% fresh water (river and local meteoric water) and 65% groundwater discharge from the Cambrian Jordan Sandstone aquifer, with no contribution from other potential surface and groundwater sources.
Soil samples from the calcareous fen indicate average Ca concentrations of about 21% (dry weight) for the calcareous fen soils vs. <8% for non-calcareous peat soils adjacent to the fen. Geochemistry and stable isotope data indicate that the carbonate material in the fen soils are precipitates from groundwater discharge rather than detrital carbonate minerals derived from overlying Ordovician Prairie du Chien Group sediments. Carbon-14 data indicate a maximum age of 850 (±100) years bp for fen peat material.
Based on the local groundwater hydrology, we should expect to see calcareous fens throughout the local floodplain of the Minnesota River. Fen occurrence, however, is limited to a few isolated locations, suggesting that some non-groundwater-related factor is controlling and limiting floodplain fen occurrence. Using field observations, survey data, and historic river stage data, we have concluded that calcareous fen occurrence is controlled by the maximum river stage during major flooding events. We hypothesize that fresh water flood events flush out carbonate particulate matter, rendering the most frequently flooded peat soils unsuitable for the calciphilic plant species.
Matthew Uliana
Weegar-Eide & Associates, LLC, Austin, TX
Matthew Uliana is a Senior Hydrogeologist-Associate with Weegar-Eide & Associates in Austin, Texas. He has a B.S. in Geology/Anthropology from James Madison University and M.A. and Ph.D. degrees in Geological Sciences from The University of Texas at Austin. He has more than 15 years of consulting experience dealing with water resources, groundwater modeling, aqueous geochemistry, and general geology, and holds a professional geoscience license in Texas.
Aaron Weegar
Weegar-Eide & Associates, LLC, Austin, TX
Aaron Weegar is an owner and Principal Hydrogeologist with Weegar-Eide & Associates. He has a B.A. in Geology from Iowa State University, and has more than 25 years of consulting experience specializing in water resources, surface mine dewatering, groundwater contamination investigation and remediation projects, in-situ mineral solution mining, and a wide variety of underground injection control projects. He holds professional geology licenses in Texas, Minnesota, and Alabama.
Jamie Swenson
I&S Group, Inc., Mankato, MN
Jamie Swenson is a Principal Environmental Manager with I&S Group in Mankato, Minnesota. She has a B.A. in Community Development from Saint Cloud State University and is currently enrolled in the Environmental Science M.S. degree program at Minnesota State University-Mankato. Swenson has more than nine years of experience as an Environmental Manager with I&S Group, and specializes in environmental permitting and compliance, watershed management, wetlands management, and GIS.
Doug Losee
UNIMIN Corporation, Mankato, MN
Doug Losee is the General Manager of Environmental Affairs with Unimin Corp. He has a B.S. in Natural Resources and Environmental Science from the University of Minnesota. Losee has more than 17 years of experience working in the environmental field. He began his career as a Hydrologist with the Minnesota Department of Natural Resources before working seven years as an environmental consultant. He has worked the last six years directly for industry environmental affairs.
