RAPID: Novel and timely geochemical responses of a sole source deep karst aquifer to a wildfire at Grand Canyon National Park

Roaring Springs, a karst spring emerging from a cave on the North Rim of the Grand Canyon, is the sole supply of water for over 4 million visitors and over 3,000 employees at Grand Canyon National Park. For several decades, the science team at the park along with partners, including Northern Arizona University, have been actively studying the complicated and remote karst system which serves as the catchment area for Roaring Springs. On July 4, 2025, a lightning strike started the Dragon Bravo fire within the spring’s contributing area. The fire spread to a substantial portion of the contributing area, including sinkholes, faults, and ephemeral streams known to contribute rapid recharge to Roaring Springs and others during snowmelt or during exceptional summer monsoon precipitation events. This project is collecting timely data related to the fire and fire suppression activities to improve knowledge of the karst system and its connections to water quality of the deep aquifer supplying the springs. The Dragon Bravo fire has the potential to be an intense natural tracer of suspended sediment, organic carbon, and other tracers released by the fire and fire suppression activities. As is typical for karst aquifers, the aquifer conduits provide pathways for rapid flow and transport of suspended solids and other products of the fire and fire suppression activities. Novel instrumentation and timely collection of water samples related to summer monsoon events and winter snowmelt will provide unprecedented information to improve knowledge of the connections between surface and subsurface hydrology. New understanding will translate to similar karst systems impacted by forest fire. The project will provide demonstrations of methods and technologies for new early alert and detection methods for the water utility at the Grand Canyon National Park to manage Roaring Springs water quality. The study will provide improved transferable methods of understanding and detecting water quality issues in fire-impacted karst aquifer systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.