Jewel Cave National Monument water resources scoping report

Sharrow, David; Albright, Jeff; Werrell, William; Wiles, Michael

Jewel Cave National Monument was set aside as a unit of the National Park System to protect the unique underground resources of a maze of containing over 100 miles of known cave passage, tightly packed, under approximately three square miles of land surface. Portions of the cave extend beyond the monument boundary, and more passages are regularly being discovered. The cave is very old, and developed under a series of environments that produced rare and unusual cave minerals. Water is one of the most critical resource concerns facing the monument because it is a very effective vehicle for transporting contaminants from the land surface into the cave. The entire known cave lies above the water table, so water movement occurs as complex percolation through the unsaturated zone. The rapidity with which water can move from the surface to the interior of the cave has been demonstrated by past investigations. Direct pathways for contaminants have been confirmed between the cave and the wastewater system and the monument's parking lot on the surface. Many water resource issues facing the monument are associated with contamination of groundwater. All of the visitor and administrative facilities in the monument are located over cave passages including: the visitors center, maintenance yard, employee housing, parking lot, and sewage lagoons. A state highway also passes through a portion of the monument and over a portion of the cave. Serious problems with the amount and quality of water reaching the cave have occurred when the wastewater system developed extensive leaks. Problems with the wastewater system have been corrected, but its location necessitates continued monitoring. Other significant issues include: an incomplete understanding of the link between surface and groundwater draining to the cave, potential contamination from the highway and parking lot, alterations in natural drainage patterns, water rights, and long-term viability of wells. The water resource issues facing Jewel Cave National Monument can be addressed without preparation of a Water Resources Management Plan, at this time. Recommendations are made in this report for each of the significant issue areas. Six project statements are attached for proposed or ongoing actions. These statements will be inserted into the monument's Natural and Cultural Resource Management Plan in order to compete for funding. Monitor Water Resources. A continuation of the current monitoring program, which should become a base-funded activity when the current project is complete. Surface and Groundwater Interactions. Further investigations into the complex interactions of surface and groundwater flow. Water Rights. Determining the status of water rights for the monument, and preparations for possible state adjudications. Hydrologic Connections With Hell Canyon. An investigation into possible hydraulic connections between the surface and subsurface as indicated by sediment deposits in the cave. Monitor Groundwater Level. Long term monitoring of groundwater levels in wells and the cave in order to protect water supplies and cave resources. Restore Natural Hydrologic Patterns. Restoration of natural hydrology if significant disturbances are found in other investigations. Other recommended actions include pursuing an outstanding resource waters designation through the state, additional monument staff to carry out the longterm monitoring and water management program, and implementing several proposed actions from the Draft General Management Plan.