In a statement on Monday, the NPS said search and rescue efforts continue.
The recent rains in the Grand Canyon area, and more widely in south-western parts of the US, are due to monsoonal showers.
A change in wind direction at this time of year pulls warm, moist air northward from the Gulf of California and the tropical Pacific, triggering storms over mountainous terrain.
The storms are difficult to pinpoint in forecasts and so can strike without warning. But because the ground is usually very dry, any heavy downpours lead to dangerous flash flooding and frequent lightning which increases the threat of wildfires.
Flood watches from the National Weather Service cover large parts of Arizona, as well as New Mexico, Utah and Colorado. There are lots of showers currently showing on the weather radar and these downpours will continue during Monday.
The threat of flooding is something that will remain for many more weeks. The North American monsoon season usually runs to the end of September.
Joey Martin told the BBC that he was at the Grand Canyon working on a transcanyon pipeline project when dense, grey clouds rolled in.
He described rain “coming down so hard and so thick that you couldn’t see the Grand Canyon walls”.
“You couldn’t see anything,” Martin said.
Visibility returned roughly 30 minutes later, he said. That’s when he saw the creek begin to rise. It eventually turned into a torrent of mud and debris that slammed into a nearby bridge connecting Martin’s work site to his living quarters.
“From where we were standing, it looked to be about 15ft tall,” he said. “That wall of debris ended up taking out the bridge right there.”
Martin said he and roughly 16 other workers were there and coordinated with NPS once it became clear conditions were unsafe. They gathered hikers in the area and headed for higher ground.
Eventually all were airlifted out.
“It was scary,” he recalled.
“Never been in any kind of vicinity of something like that to that caliber,” he said. “Staying calm was hard, but everybody kind of played a part in keeping people calm and keeping people, you know, focused on just getting away from the danger.”
The NPS initially said it was looking for information about 15 people who were thought to be missing or unaccounted for.
It reported that flooding had caused significant damage in some areas and that trails in the area have been closed.
Overnight guest lodgings in the South Rim will be stopped from Monday until further notice as the floods have caused “extensive damage” to the national park’s water infrastructure.
On Monday, the NPS said that preliminary assessments indicate about 40% of the Transcanyon Waterline, which delivers water for visitors and approximately 2,500 residents, was damaged or destroyed in the flood.
The NPS asked anyone who knew of hikers or backpackers who were in the inner canyon along the Bright Angel Creek corridor on Saturday to get in touch.
