“So if stormwater were to penetrate the breccia pipe it could find its way all the way down to groundwater,” said Malcolm Alter, a former geologic engineer who authored the study.

His study didn’t examine whether similar fractures extend from other breccia pipes, but Alter said the way to make sure water doesn’t pass from uranium rock to groundwater is to keep the mines dry.

Other studies on the north rim of the Grand Canyon suggest that water’s movement from surface to aquifer could be happening over a matter of days or weeks. For three years, Grand Canyon National Park hydrologist Ben Tobin has been putting fluorescent dye in sinkholes on the Kaibab Plateau, then tracking drainages and springs in the canyon to see where the dye turns up. In one test, it took less than a month for dye injected on the Kaibab Plateau to turn up in water sources as far as 26 miles away and 6,000 feet lower than where it began, Tobin said.

Another study by a graduate student at Northern Arizona University showed that after a monsoon event, it took just days to measure a response in springs fed by the regional aquifer, Tobin said.