42-8 Determining Groundwater Flow Patterns in a Glacially-Influenced Midwestern Wetland

Abstract:

Wetlands provide critical ecological functions including groundwater storage and recharge, nutrient cycling, and biodiversity support. The Fish Lake Environmental Education Center is a 240-acre glacially-influenced site near Lapeer, Michigan, that includes a bog, kettles with vernal pools, and interconnected surface water features. Previous research at Fish Lake has investigated groundwater recharge, groundwater/surface water interactions, wetland chemistry, and the influence of precipitation on groundwater flow and water quality.These studies demonstrated that precipitation strongly influences groundwater levels and chemistry within the wetland system. However, groundwater flow relationships between the bog, kettles, and surface water features have not been evaluated in detail. 

This study characterized subsurface flow patterns within the Fish Lake wetland system to evaluate how wet and dry years influence groundwater-surface water interactions and recharge/discharge dynamics. Groundwater elevation data were obtained using pressure transducers, manual water-level measurements, and high-resolution survey data, which were used to develop groundwater flow maps. Long-term monitoring data including precipitation, groundwater elevations, electrical conductivity, pH, temperature, and nutrient concentrations were also evaluated to compare hydrologic conditions during wet and dry periods. Groundwater flow direction within the bog alternated flow directions between wet and dry years. This reversal suggests that precipitation-driven changes in hydraulic gradients influences groundwater/surface water interactions and recharge/discharge processes within the wetland system. This research contributes to long-term hydrogeologic monitoring efforts at Fish Lake and supports broader applications in wetland management, watershed protection, and climate resilience planning for similar upper Midwestern wetland environments.

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