The organizer of a Grand Canyon adventure described it as a chance to trek along the South Rim, “one of the greatest hikes in the planet.”

By September, at least 100 people from 12 different states had signed up on Facebook for the one-day hike. The organizer, Joseph Don Mount, said on Facebook he hoped more people would sign up for the hike.

“If you want to keep inviting friends, I am determined to make this work for as many who want to go,” Mr. Mount said, according to federal court documents.

A tipster sent the Facebook post to officials at the Grand Canyon National Park, where hikes had been limited to no more than 11 people per group in response to the pandemic.

When a park official contacted Mr. Mount, he denied that he was planning a large-scale trip.

Yet, he continued to advertise the hike and to organize cabin stays and shuttle rides for dozens of people, according to court documents. By Oct. 24, the day of the hike, more than 150 people had paid $95 to register for the trip, the documents show.

That morning, at least 150 people showed up at the North Kaibab Trail, astounding rangers and overwhelming other visitors who struggled to steer clear of the hikers, many of whom were not wearing masks or social distancing, according to the documents.

On Tuesday, Mr. Mount was charged in the U.S. District Court in Arizona with five separate counts, including giving a false report, interfering with a government employee or agent acting in an official duty, soliciting business in a federal park without a permit, and violating restrictions for group sizes for park visits and restrictions related to Covid-19.

Mr. Mount did not immediately return messages seeking comment. It was unclear from federal court records whether he had a lawyer.

In an interview with The Daily Beast, Mr. Mount said he had arranged the trip because “with Covid and everything, people were just itching to get out.”

“I didn’t do it for profit,” he said.

Timothy Hopp, a U.S. park ranger, said in an affidavit that Mr. Mount collected $15,185 from participants for the hiking event.

Mr. Mount planned to use the money to pay for two buses, three passenger vans, hotel lodging and about $2,900 for the drivers’ tips, meals, fuel, car pool drivers and other expenses, according to the affidavit.

Mr. Mount “knowingly profited from leading this commercially organized” event, Mr. Hopp said. “J. Mount admitted he would be receiving a net profit of $65.11 and it would be enough to buy a new pair of hiking poles.”

Mr. Hopp said he contacted Mr. Mount in October after receiving the tip, and Mr. Mount told him at the time that he was taking a “small group of close rugby associates and family friends.”

Mr. Hopp said he repeatedly told Mr. Mount that the limit for group tours of the rim were 11 people and that groups could not be split up to circumvent the size limit because of the pandemic.

Mr. Mount’s planned hike exceeded the limit set even during normal times, when up to 30 people are allowed in a group, Mr. Hopp said.

After the conversation, Mr. Mount told hikers that he was backing out as their trip leader but said the transportation plans remained in place and cabins and hotels were still booked.

“Remember — there is nothing stopping you from hiking the Grand Canyon on this day,” he wrote, according to court documents. “However, there is now a target on my back and this is the best way I know to still hike” and “not be tied to any of you.”

He told the hikers he would be in his own group and advised them to travel in groups of no more than 11 people.

“Ranger Hopp — this is my plausible deniability,” Mr. Mount wrote on Facebook. “I am no longer leading a group through Grand Canyon on 10/24.”

At 5 a.m. that day, a caravan of cars arrived at the trailhead. A ranger on the trail saw at least 150 people walk through the area between 7:30 a.m. and 8 a.m.

The ranger, Cody Allinson, said that in seven months of work he had never seen “so many individuals traveling in the same direction in such a condensed period of time and space,” according to the affidavit.

When park rangers approached them, many hikers were evasive.

“It was obvious they had been coached not to identify with their fellow participants,” one ranger said, according to court documents.

Hikers who were not with the group later complained to the park service about the sheer number of people they encountered on the trail.

“There was no social distancing, nobody was wearing masks,” one of the visitors complained, according to court documents. “The group size was way out of control,”

The day after the hike, some of the participants praised Mr. Mount on Facebook and suggested everyone send him a “bonus for all the extra hard work he did planning a weekend of memories.”

It was not clear from the affidavit whether Mr. Mount received the bonus.