HYDROLOGY OF GOLIATH'S CAVE, FILMORE COUNTY MINNESOTA

Goliath’s Cave is 2.39+ miles long and developed in the Ordovician Dubuque and Stewartville Formations in Fillmore County, Minnesota. The west half of the cave is under the Cherry Grove Blind Valley Science and Natural Area (SNA). The east half of the cave is part of John Ackerman’s Minnesota Cave Preserve (MCP). In Goliath’s Cave, two underground steams emerge from the SNA section, join in the MCP section, flow east, and ultimately sump. Previous dye traces have documented resurgence of the water in the Canfield Big Spring complex that is the headwaters of Canfield Creek, a Designated Minnesota Trout Stream.

Human impacted water from a sinking stream, tile drains, and surface runoff sinks at several places into the SNA depending on the volume of the runoff. Fluorescent dye traces were conducted from three different sink points in the SNA to identify the sink points that supplied water to the two flow systems under the SNA. Rhodamine WT was injected in sink (23B143) near the Goliath’s natural entrance. Eosine was injected in sink (23B144) fed by a tile drain outlet east of Coon Sink. Fluorescein was injected in Downwater Sink (23B20). The Rhodamine WT and eosine dyes emerged in the northern flow system and the fluorescein emerged in the southern flow system. These results indicate multiple and independent flow networks supply water from the surface to the cave system. Travel times from each dye injection point to the confluence of the two flow systems was under two hours documenting rapid, direct connections between the surface stream and the cave stream.

Water chemistry data indicate surface water, some that originates from tile drains, had greater nitrate-nitrogen levels and more elevated Cl/Br ratios than that of Goliath’s Cave, and the surface water influence Goliath’s Cave. The data also indicated that larger volumes of water resulted in elevated nitrate as nitrogen concentrations and Cl/Br ratios in the waters.

This study found there to be rapid flow rates and responses between the three sinks and water in Goliath’s Cave. The study also determined that anthropogenic activities influence the water quality Goliath’s Cave and hence the aquifer. Future work is needed to further delineate the entirety of all the sinkholes that supply surface water to Goliath’s Cave during all flow conditions.