The secret underground system keeping the Grand Canyon alive

That water comes from a single source: Roaring Springs, a cave-fed spring on the North Rim. Although hikers can hear and glimpse the spring from the North Kaibab Trail, there is no trail leading directly to it. Roaring Springs provides water not only for park visitors but also for the plants, animals, and ecosystems that depend on it. As the region becomes hotter and drier, protecting this vital water source is becoming increasingly important.

Researchers at Northern Arizona University's School of Informatics, Computing, and Cyber Systems are working to better understand how Roaring Springs and other cave-fed springs function. With support from a new grant funded by Grand Canyon National Park, the team will expand efforts to map these water systems and investigate how snowmelt is connected to the springs.

"Understanding where the water sinks is critical for the infrastructure, the animals, the plants and the rest of the ecosystems that rely on these springs," said Blase LaSala, a Ph.D. student in ecoinformatics. "They're like oases."

Early findings from the project were recently published in Scientific Reports.

Mapping the Grand Canyon's Hidden Caves

Most people will never enter the caves that feed Grand Canyon springs. They are closed to the public and often located far from established trails. As a result, much of what scientists know about them comes from specialized mapping projects.

For his doctoral research, LaSala worked with professor Temuulen "Teki" Sankey, an expert in remote sensing, to create detailed maps of several cave systems. Using a mobile lidar scanner, the team produced high-resolution three-dimensional models that captured cave walls, ceilings, passages, and chambers in remarkable detail.

Over 45 days, researchers, volunteers, and park staff documented more than 10 kilometers of underground passages and rooms.

"I had no idea how large and long these caves are," Sankey said. "We have been able to produce really high-resolution 3D maps, which, from a remote sensing perspective, is what's unique and novel about it. Grand Canyon's caves have never been mapped in 3D like this."

The work required major logistical effort. Team members carried packs weighing up to 55 pounds, including lidar equipment, while hiking to remote cave entrances that could take as long as two days to reach. Once inside, they climbed, rappelled, crawled, and even floated through flooded sections while recording the caves' shapes and fracture patterns.

Those details are valuable because cave formation follows recognizable geological processes. The arrangement of passages, cracks, and openings can reveal how water travels through different layers of rock beneath the canyon.

Following Snowmelt to Roaring Springs

The simplest explanation for where the water comes from is the surface, particularly snowmelt from the Kaibab Plateau.

The more difficult question is how that water travels underground before emerging at springs like Roaring Springs.

The cave-fed springs are located within Redwall and Muav limestone formations. Several other rock layers sit between those springs and the surface above. Previous dye tracing experiments conducted by the park have shown that water can move surprisingly quickly through this underground system.

Abe Springer, a professor in NAU's School of Earth and Sustainability and a collaborator on the project, has worked with the park on dye tracing studies. In some tests, dye poured into sinkholes on the plateau traveled roughly 20 kilometers and appeared at springs in as little as a week.

Exactly how the water moves through the subsurface remains uncertain. Factors such as fractures, faults, rock permeability, and underground pathways all influence the journey.

"The dissertation work was making the geologic connection between what we might see at the surface versus what we might see hundreds or thousands of feet belowground," Sankey said.

"It's like looking at a black box," LaSala added. "You see what comes in and what comes out, but it's very hard to quantify what's going on in there. Now that we know what patterns are there, we can really start to relate the data to spring change over time."

Water Quality and Contamination Risks

Understanding these underground pathways is important for more than scientific curiosity. It also has practical implications for water quality and public safety.

The Grand Canyon's largest springs are fed by karst systems, which Sankey compares to "Swiss cheese" because of the numerous holes, channels, and openings in the rock. Water can move rapidly through these pathways, leaving little opportunity for natural filtration.

That means contaminants may travel quickly as well. Runoff from wildfire burn areas or bacteria such as E. coli could enter sinkholes connected to Roaring Springs Cave and reach the water supply. If contamination is detected, park officials may need to temporarily shut down pumping operations until the issue is addressed.

By identifying where water enters the system and tracing how it moves, researchers can help managers pinpoint contamination sources and reduce the risk of future disruptions.

New Research on Snowmelt and Sinkholes

The next phase of the project is scheduled to begin in early 2026.

Using airborne lidar surveys and satellite observations collected over several decades, LaSala and Sankey plan to map sinkholes on both sides of the Grand Canyon while examining patterns of snow accumulation and snowmelt over the last 40 years.

Much of the upcoming work will focus on surface features, although researchers remain interested in exploring newly discovered caves if opportunities arise.

The goal is to better understand the geological processes that influence sinkhole formation, disappearing streams, and underground water movement. Researchers will compare patterns observed at the surface with those documented inside caves. The findings will also guide future dye tracing experiments.

Snowmelt is an especially important focus because Arizona has experienced declining snow levels over time, and the Grand Canyon region has followed the same trend.

The project will create an extensive archive of environmental data that can be combined with lidar and other imaging resources to improve understanding of water systems throughout the region.

Why the Findings Matter Beyond Arizona

Although the research directly benefits Grand Canyon National Park, its significance extends well beyond northern Arizona.

More than one billion people around the world rely on water from karst springs. Improving scientists' understanding of how water moves through these complex underground systems could help inform water management efforts globally.

The findings may also prove valuable for Native American tribes located within or near the park.

"It's exciting to find patterns that verify the hypotheses made over 50 years ago," LaSala said. "We have all this amazing data now, and we're trying to combine it with other data to find useful things. There are so many places that could benefit from this type of analysis."

How the Dragon Bravo Fire Affects the Study

Researchers expect the Dragon Bravo Fire to influence future observations, but they view it as another factor to incorporate into their work rather than an obstacle that changes the overall mission.

When asked how the fire might affect the project, both LaSala and Sankey acknowledged that unexpected developments are common in scientific research.

"It's a new twist to our study," Sankey said.

The fire's effects on the Kaibab Plateau will likely alter some of the environmental conditions researchers are monitoring. As the project continues, those changes will be incorporated into the analysis, and the team plans to assist the park however possible in understanding the fire's impacts.