Flash flooding causes major damage, forces evacuations in part of Grand Canyon National Park

The flash flooding that damaged Bright Angel Canyon and Phantom Ranch in Grand Canyon National Park is a warning for Tucson residents and other Southern Arizonans who plan summer trips into desert and mountain canyons. The flooding forced emergency evacuations, destroyed most footbridges over Bright Angel Creek and closed several major routes and river crossings. With more thunderstorms and heavy rain possible in the coming days, park officials are cautioning visitors that conditions can change quickly, even when rain is falling miles away.

The National Park Service said flooding began at about 2:30 p.m. Saturday and moved through the Bright Angel Canyon and Phantom Ranch areas. At least 62 people were evacuated from Phantom Ranch and the lower North Kaibab Trail. Additional evacuations were expected Sunday at Phantom Ranch, Cottonwood Campground and other nearby locations as crews continued examining the damage and determining where visitors could safely travel.

Nearly all footbridges crossing Bright Angel Creek were destroyed, according to the Park Service. The agency has closed the Black Bridge and Silver Bridge over the Colorado River indefinitely, along with other impacted areas. Officials have not provided an expected reopening date, and more closures remain possible while damage assessments continue. For hikers, backpackers and park employees, the destruction of crossings could affect access through one of the canyon’s most heavily traveled corridors.

The flooding also temporarily shut down the Colorado River to river traffic after debris and metal structures washed into the water. River parties already inside the canyon are being directed by river operations rangers and through the Grand Canyon River Alert system. Visitors with upcoming river trips have been told to contact their commercial outfitter or the National Park Service River Permits office for information specific to their itinerary. The closures mean that a planned trip could be affected even if the flooding occurred far from a visitor’s launch point or scheduled destination.

The danger is especially relevant to people from Tucson because the same storm pattern can produce rapidly changing conditions across Southern Arizona. On Saturday, the National Weather Service in Tucson issued severe thunderstorm and flash flood warnings for Pima and Pinal counties, including Tucson, Mount Lemmon, Oro Valley, Marana, the Catalina Foothills, Sabino Canyon Recreation Area and Saguaro National Parks East and West. Forecasters warned of wind gusts reaching 70 mph, small or quarter size hail and flooding in washes, streets, underpasses and other low lying areas.

One flash flood warning covered eastern Pima County after radar indicated that thunderstorms had dropped between three quarters of an inch and 1.25 inches of rain in parts of the eastern Tucson metro area in only half an hour. The weather service specifically identified drainages feeding Agua Caliente and Tanque Verde creeks as areas where flooding was ongoing or expected. Locations listed in the warning included Harrison Road at Pantano Wash, Agua Caliente Wash, Wentworth Road at Tanque Verde Wash, Tanque Verde Loop Road, Escalante Road at Atterbury Wash, Freeman Road and Limberlost Road.

Another warning covered southeastern Pinal County after storms produced between three quarters of an inch and 1.5 inches of rain in the northern Catalina Mountains. An automated gauge at Oracle Ranger Station recorded 1.54 inches. The warning included Oracle, Saddlebrooke, San Manuel, Campo Bonito and Biosphere 2, as well as Route 77. Severe thunderstorm warnings also moved through areas near Davis Monthan Air Force Base, Tanque Verde, Vail, Rita Ranch, Summerhaven and San Manuel, with officials warning that wind could damage roofs, siding, trees, vehicles and mobile homes.

The National Weather Service describes Arizona flash floods as sudden events that can develop in minutes and occur even when skies overhead appear clear. Rain falling upstream can funnel into normally dry washes and riverbeds. Desert ground can absorb water poorly, particularly after long dry periods, while steep mountains, narrow canyons and areas affected by wildfires can accelerate runoff. An inch of rain or less in an hour can be enough to trigger flooding, depending on how quickly and where the rain falls.

For Tucson area residents heading outdoors, officials advise moving indoors at the first sound of thunder because lightning can strike miles from a storm. People should wait 30 minutes after a storm passes before resuming outdoor activities and secure loose objects when there is time to do so. Drivers should never attempt to cross a flooded roadway, since most flood deaths occur in vehicles. In the Grand Canyon, the latest damage shows why those precautions also apply to hikers, campers and river travelers: a familiar trail or bridge can become impassable without warning, and reopening decisions may take time as park crews inspect the canyon.