The body of a 46-year-old man was recovered on Sunday evening near Crystal Rapids along the Colorado River, the National Park Service said on Sunday.
Weekend flooding in Arizona's Bright Angel Creek, which flows into the river, happened on Saturday afternoon.
More than 60 people were evacuated from the depths of the canyon.
The park service said it had yet to account for 15 people and asked anyone with details about hikers or campers in the canyon to get in touch.
The Arizona Department of Public Safety was helping with additional evacuations.
Because the main water line was out of service, tourists won't be able to stay overnight at lodges and hotels within Grand Canyon National Park.
Permanent residents are being asked to conserve water.
"These measures are crucial for ensuring the safety and sustainability of water resources," the park said in a statement.
Parth Desai was hiking through a narrow passage in Bright Angel Canyon with fellow physicians and a park ranger when the downpour started on Saturday.
"We saw the creek flood, waterfalls coming up out of nowhere, boulders, mud, landslides happening everywhere," he said.
Later, as they made their way toward Phantom Ranch, a colleague shouted "Up, Up, Up, Up!" as a one metre debris wall headed toward them and they ran up into a patch of cacti, he said.
They were rescued by helicopter late Saturday after making it to the Phantom Ranch area.
Torrents of water wiped out footbridges over the creek and altered the landscape, widening the creek bed and extending an existing river rapid or creating a new one.
The flood was a major blow to an enduring effort to modernise the pipeline that serves six million visitors a year and roughly 1600 residents of Grand Canyon Village.
Popular tourist spots, including the Bright Angel Campground, the North Kaibab Trail and Phantom Ranch, home to a historic canteen and dormitories, remained closed on Sunday.
with dpa
