Integration of Water Tracing and Structural Geology for the Delineation of Springsheds

Abstract

Fountain, Fillmore Co., Minnesota, a small town self-identifed as “The Sinkhole Capitol of the U.S.A.,” is located on a large sinkhole plain in the Upper Ordovician Galena Group. Recent mapping of the structural setting in the Fountain area provides new constraints for the interpretations of flow paths in springsheds defined by three decades of dye traces (Runkel, 2012, private communication). The strata of the Galena Group are deformed into a low-angle, assymetric syncline that is plunging northwest. The Fountain East dye traces, initiated in May 2012, were designed to further refine springshed boundaries on the northern edge of the sinkhole plain and to delineate source areas for cold-water springs that feed Minnesota designated trout streams in the area, particularly Rice Creek. Two major springsheds were previously mapped in the Fountain East area: the Fountain Springshed, which drains northwest and forms the headwaters for Rice Creek; and the Mahoney Springshed that drains southeast to form the headwaters for Mahoney Creek. The newest tracing efforts begin to document a new springshed to the northeast of Fountain feeding Klomp’s Spring and ultimately Rice Creek. The integration of dye trace data, structural contours, and ArcGIS imagery contextualizes the regional subsurface flow and further provides evidence for the delineation of the Fountain, Mahoney and Klomp Springsheds. Knowledge of the structural setting of the Fountain East trace area is a significant step in answering broader questions regarding the hydrogeologic behavior of the Galena Group karst system and its role in the productivity of designated trout streams.