TUCSON, AZ (Tucson News Now) - During the perfect storm, rushing, muddy waters fill our normally dry and dusty washes. Just 10 years ago that happened in the Rillito River.
Five days of downpours over the Santa Catalina Mountains flooded the river to record-setting levels and the normally dry waterway was filled bank-to-bank.
Before rushing into the Rillito River, these same floodwaters destroyed infrastructure in Sabino Canyon. The scene was dramatic in this popular recreational canyon tucked into the mountains. Bridges were washed away,buildings were turned to rubble and roads were covered in boulders.
"The hillside literally gave way," said U.S. Geological Survey Research Hydrologist Chris Magirl, while visiting the recovering canyon in May 2016.
Magirl said the damage was the result of debris flows, which he described as "a slurry of concrete" filled with rocks, boulders, plants and mud.
Even now, you can see what the destruction left behind.
Pointing to a lighter patch of dirt on the mountainside, Magirl said "we're looking at a debris flow scar on the hillside. When people come to Sabino today or even from Tucson they can look up and see these scars."
Much of the canyon infrastructure has been rebuilt at cost of millions of dollars.
Heidi Schewel, Public Information Officer with the U.S. Forest Service, was one of the first people to see the damage. She said it took "over a year to get things back to fully functional again."
The damage wasn't just in Sabino Canyon. Over 600 hundred debris flows crashed down in four different mountain ranges in a matter days. The risk of this happening during the next perfect storm is nearly impossible.
"To our minds that happened back in the ice age," Magirl said. "It really wasn't a process active today."
So next time you see a pile of boulders blocking your way, take a moment to think about how it got there.