The Geology and Ecohydrology of Springs in the Driftless Area of Southwest Wisconsin
What: The Driftless Area of southwest Wisconsin is home to thousands of springs that help to support the region’s world-class trout streams and sustain critical habitat for endangered and threatened species. Springs provide evidence of heterogeneity of permeability in the subsurface. As such, spring occurrence and geochemistry can provide important insights into local influences on groundwater flow and aquifer contamination susceptibility. Students on this project will work together to better understand geological controls on the distribution of springs in the region and the contributions of springs to stream ecology.
When: July 12-August 9
Where: Project members will spend three weeks in the field in the Driftless Area of southwest Wisconsin. We will be based in the picturesque Mississippi River Valley of Crawford County, Wisconsin. The final week of the program will be spent on the campus of Beloit College, where we can take advantage of the laboratory and computer facilities in new Center for the Sciences.
Who: Six students
Project Faculty: Susan Swanson, Associate Professor of Geology, Beloit College, Maureen Muldoon, Associate Professor of Geology, University of Wisconsin – Oshkosh
Project Description and Goals
The goals of the project are to:
- Characterize and describe the sedimentary strata in the vicinity of spring systems to better understand the features that influence discrete flow and improve upon conceptual models of spring flow in the region. Although recent studies have improved knowledge of the distribution of spring resources (Macholl, 2007; Swanson et al., 2007), the hydrogeologic controls on the majority of the spring systems in the region remain poorly studied. Studies of the Cambrian Tunnel City Group (Swanson, 2007) and the Silurian dolomite (Muldoon et al., 2001) have shown that stratigraphically-controlled features can be important influences on preferential groundwater flow. Combined outcrop and core studies of the other Cambrian and Ordovician age strata in the vicinity of spring systems, in combination with existing information (e.g., Michelson and Dott, 1973; Dott et al., 1986), may elucidate similar relationships. Results of such studies could further the argument that detailed lithostratigraphic information can aid in characterizing hydrostratigraphy and evaluating potential for discrete flow. Because the Cambrian and Ordovician units are heavily utilized for water supply purposes throughout the Upper Midwest, the potential for discrete flow through these aquifers and the predictability of such zones also has important implications for the development of effective aquifer-management strategies. A fuller understanding of spring flow paths can also lead to more effective conservation or restoration strategies for individual springs and their receiving waters.
- Use physical hydrologic conditions to understand patterns of discrete versus diffuse groundwater discharge to springs and their receiving waters. Springs in Wisconsin help create unique habitat for endemic species of plants and animals because they often provide a stable physical and chemical environment. Springs can maintain stream flow during dry periods and provide refuge to organisms from heat in summer and cold in winter. Additional benefits may include increasing concentrations of dissolved oxygen and adding small amounts of nutrients that are essential to the health of organisms (Webb et al., 1998; Grannemann et al., 2000). Studies of flow, temperature, and geochemical conditions in spring pools and spring receiving waters can contribute to the development of effective conservation strategies where stream-aquifer interactions create beneficial aquatic habitat. In addition, patterns of flow, temperature, and geochemical conditions along stream reaches have the potential to reveal significant aquifer heterogeneities.
- Investigate unique spring systems that support biological communities uncommon to the region and/or have the potential to provide longer term records of hydrologic conditions. Springs that deposit tufa are uncommon in Wisconsin, but several are known to exist in the Driftless Area (Heller, 1988). These springs are capable of supporting diverse biological communities that sometimes mediate the carbonate precipitation. They may also provide a special opportunity to study paleoclimatic conditions because variability in δ18O of the tufa deposits is driven by changes in temperature and the δ18O of water that recharges the aquifer and flows to the spring. Depending on the extent and persistence of deposition, seasonal-, decadal-, and centennial-scale variations in climate can be recorded (Andrews, 2006).
Listed below are potential student projects within the overall project’s goal of evaluating the influence of stratigraphically-controlled features on preferential groundwater flow and their contributions to the ecohydrology of springs in the Driftless Area of southwest Wisconsin.
- Conduct outcrop and core studies of clastic and/or carbonate sedimentary bedrock units to better understand the distribution of stratigraphically-controlled features and their influence on the formation of springs in the region.
- Map karst features, such as sinkholes and caves, and relate their distribution and development to the distribution of springs in the Driftless Area.
- Measure and map patterns of dissolved oxygen and nutrient conditions and/or flow and water temperature conditions in springs and trout streams in the Driftless Area to determine influences of preferential flow and contributions to aquatic habitat.
- Investigate heavy metal geochemistry (Zn, Pb, Cu, Ni) of spring waters to determine groundwater flow paths to springs and streams in the Upper Mississippi Valley Lead-Zinc District.
- Utilize groundwater flow and temperature models to better understand the influence of stratigraphically-controlled features on aquatic habitat.
- Collect core of spring tufa deposits and analyze spring water and spring tufa deposits for stable isotopes of oxygen to provide insights into changes in hydrology and climate over time.
The group will spend three weeks in the Driftless Area of southwest Wisconsin and one week on the Beloit College campus. A log cabin in the Mississippi River Valley will serve as our base in the Driftless Area, and we will drive to students’ field sites in Crawford and adjacent counties on a daily basis. Fieldwork will involve wading in streams, walking through wetlands, and climbing on rock outcrops. Therefore, in addition to hiking shoes, waterproof knee boots are highly recommended. The log cabin that we will stay in has a loft with six single bunks for the students. It also has a fully-equipped kitchen, so the group will cook together. While on the Beloit College campus, students will be housed in dorms.
Students should have completed at least one course in hydrogeology, sedimentology/stratigraphy, geochemistry, or geomorphology (with an emphasis on fluvial geomorphology). Introductory or advanced courses in chemistry or freshwater ecology are also desirable.
- Andrews, J.E., 2006, Paleoclimatic records from stable isotopes in riverine tufas; synthesis and review: Earth-Science Reviews 75 (1-4), pp.85-104.
- Dott, R.H., Byers, C.W., Fielder, G.W., Stenzel, S.R., Winfree, K.E., 1986. Aeolian to marine transition in Cambro-Ordovician cratonic sheet sandstones of the northern Mississippi Valley, USA: Sedimentology 33, pp.345–367.
- Grannemann, N.G.; Hunt, R.J.; Nicholas, J.R.; Reilly, T.E.; Winter, T.C., 2000, The importance of ground water in the Great Lakes region: U.S. Geological Survey Water-Resources Investigations Report 2000-4008, 14 p.
- Heller, S.A., 1988, Seasonal geochemistry of two tufa-depositing springs in southwestern Wisconsin: Geoscience Wisconsin 12, pp.77-83.
- Macholl, J.A., 2007, Inventory of Wisconsin’s Springs: WGNHS Open File Report 2007-03, 20 p. plus appendices.
- Michelson, P.C., Dott, R.H., 1973, Orientation analysis of trough cross stratification in Upper Cambrian sandstones of western Wisconsin: Journal of Sedimentary Petrology 43 (3), pp.784–794.
- Mudrey, M.G., Jr., Brown, B.A., Greenberg, J.K., 2007, Bedrock geologic map of Wisconsin: WGNHS State Map 18-DI, version 1.0, 1 CD-ROM.
- Muldoon, M.A., Simo, J.A., Bradbury, K.R., 2001, Correlation of hydraulic conductivity with stratigraphy in a fractured-dolomite aquifer, northeastern Wisconsin, USA: Hydrogeology Journal 9, pp.570-583.
- Swanson, S.K., 2007, Lithostratigraphic controls on bedding-plane fractures and the potential for discrete groundwater flow through a siliciclastic sandstone aquifer, southern Wisconsin: Sedimentary Geology 197, pp.65-78.
- Swanson, S.K., Bradbury, K.R., Hart, D.J., 2007, Assessing the Ecological Status and Vulnerability of Springs in Wisconsin: WGNHS Open File Report 2007-04, 15p. plus appendices.
- Webb, D.W., Wetzel, M.J., Phillippe, L.R., 1998, The aquatic biota and groundwater quality of springs in the Lincoln Hills, Wisconsin Driftless, and Northern Till Plains of Illinois: Illinois Natural History Survey, Center for Biodiversity Technical Report 1998 (6), 164p.