UTILIZING KARST RESEARCH TO INFORM THE NEPA PROCESS AT GRAND CANYON NATIONAL PARK

Grand Canyon National Park (GRCA) relies exclusively on a karst spring to supply water to both the North and South Rim communities and approximately 5 million visitors per year. This spring, Roaring Springs, is fed entirely from focused, ephemeral snowmelt that sinks into the karst landscape above the rims and emerges in the canyon walls 3,500 feet below. Current water infrastructure that pipes this water from the spring back to the rims has far outlived its life expectancy and the park is currently looking at alternatives for replacing it. As part of the National Environmental Policy Act (NEPA) procedures, the park is undertaking numerous studies to determine the environmental impact of these alternatives. There is a lack of borehole data, deep geophysical surveys, or other data to characterize the deep aquifers away from the outcrops of the Canyon. To improve the characterization of the aquifer, a combination of dye tracing, hydrograph, chemograph, and ion analyses are being used to establish a baseline understanding of aquifer behavior. These data are providing critical information to guide the NEPA process, leading GRCA towards the least impactful and most sustainable option for the future of the park’s water supply system.