A pipeline on the San Francisco Peaks that provides water to Flagstaff has been shut down after it suffered heavy damage during recent monsoon rain. Many areas northeast of Flagstaff have seen cataclysmic flooding following this year’s wildfires.
City officials say there are several breaks in the Inner Basin waterline. But the most significant damage appears to be in areas that were burned during the Pipeline Fire in June. Flooding also caused heavy erosion, debris flows and rock fall on forest roads, complicating assessment efforts. City staff are hiking the area and using drones to determine the extent of the impacts.
"To date, we don’t really know the damage. It’s really hard to get up there, just the amount of flood events we’ve had, the amount of stream incision, erosion and also fill, the amount of debris flows," says City of Flagstaff Stormwater Manager Ed Schenk.
Repair is expected stretch into the millions of dollars, but work won’t begin anytime soon as more flooding events are still possible before the end of monsoon season.
It’s still unknown whether the waterline on the west side of the peaks near Schultz Creek has also been damaged.
The Inner Basin pipeline provides up to a fifth of Flagstaff’s drinking water during the summer. The city plans to further tap groundwater wells and Lake Mary to make up the difference. The waterline was damaged following the 2010 Schultz Fire, and officials say many previous repairs appear to have held.
They plan to shore up the newly affected areas and eventually return the pipe to service.
