This March 2008 photo shows the Grand Canyon at a bend in the Colorado River. (Matt York/AP)

Out on the river, with the sheer, many-colored cliffs of the Grand Canyon looming overhead, one woman said she felt terror as a fellow National Park Service employee yelled at her drunkenly, an ax in one of his hands.

Another woman recalled how a supervisor harassed and belittled her after she rejected his attempts to flirt. He questioned her abilities in front of colleagues, insisting she should never have been hired. And she thought that he was the one who placed ammunition cans filled with human waste outside her tent.

Still more claimed that one of the boatmen on their team would refuse to take them to their work sites if they rejected his sexual advances. One employee even said that the boatman withheld food from those who refused him.

Women on these Park Service boat trips, that employee told Interior Department investigators, were forced to “walk the line” between “not being hated and not being desired.” It was a near impossible balancing act.

These details come from a federal investigation into allegations of harassment on National Park Service river trips through the Grand Canyon. A report published Tuesday found “evidence of a long-term pattern of sexual harassment and hostile work environment” for at least 19 people during these trips at one of America’s most spectacular natural wonders, as boatmen and a supervisor pressured female colleagues for sex and retaliated against some who refused or reported them.

The long river trips — which are used for a combination of research, education and maintenance of trails and shorelines and staffed by a mix of Grand Canyon National Park employees and outside contractors — were known for their “laissez faire” culture, one human resources manager told federal investigators. There was a sense that, “what happens on the river, stays on the river,” she said.

Co-workers would spend weeks at a time on the narrow waterway that snakes between the Grand Canyon’s towering walls, cut off from cellphone service and most signs of civilization and with no one to interact with but each other.

Another human resources specialist said that the park was a “good ol’ boy network” and that female victims of misconduct had a hard time getting their complaints taken seriously.

The investigation was prompted by a 2014 letter of complaint from 13 current and former Grand Canyon employees citing incidents of abuse over a span of more than a decade. The complaint alleged that women working for the Grand Canyon River District were subjected to “discrimination, retaliation and a sexually hostile work environment” and that reports of abuse were mishandled or ignored by the park hierarchy.

The Interior Department’s investigation found 13 instances where Park Service employees were disciplined for sexual misconduct, but the report concludes that harassment complaints were treated so haphazardly that many women chose simply not to come forward.

And although there was not sufficient evidence that the suspension of two female employees for twerking during a dance party was retaliation for their complaints against men who they said had harassed them, several supervisors with the Interior Department spoke to said that the punishment was too harsh — particularly compared with the lack of discipline for men who were accused of groping, propositioning or bullying their coworkers.

“No NPS employee should ever experience the kind of behavior outlined in the report, and it is even more disappointing because previous efforts to change the culture at the river district of the Grand Canyon failed to improve working conditions,” National Park Service spokesman James Doyle wrote in an email to the Associated Press on Tuesday.

Since the initial complaint in 2014, the Park Service now requires a pre-trip briefing for all trip participants and bars all consumption of alcohol during trips. It also took the power to remove trip participants away from the trip leader — usually a veteran river trip guide — and gave it to the project leader — a supervisor overseeing the research or maintenance projects for the trip.

The agency is still considering a number of other reforms, Doyle said, including requiring nightly check-in calls over a satellite telephone, the presence of a supervisor on every trip and the installation of a “regional ombudsman” outside the park’s chain of command to deal with complaints. The latter would be an unprecedented new policy for the National Park Service, according to the AP.

None of the people involved are named in the report, but it centers on four male employees of the National Park Service: three boatmen (who operate the watercraft used on the trips) and one supervisor. One male Park Service employee told investigators that the men “all tried to get laid as much as possible” during river trips and that there was “some sort of wager . . . or challenge between the three of them . . . to see who would get laid the most.”

The man identified as Boatman 2 resigned in June 2006 after serving a 30-day suspension for taking a photograph under a female co-worker’s dress. He was also accused of making sexual remarks to colleagues and harassing women.

Boatman 1 resigned in July 2013 after he was suspended for two weeks for groping and propositioning an employee. The supervisor, who was described as a “classic bully” who once spat beer on a woman’s head during a trip, served a 10-day suspension in 2005 for grabbing the crotch of a contract employee. He retired in May 2015.

The third boatman was never disciplined, according to the report, but he was involved in the majority of complaints listed in the Interior Department’s report. Co-workers described him as a “womanizer” and spoke of how he made suggestive comments to women or touched them inappropriately. If they rebuffed him, female Park Service employees said he would refuse to take them to their work sites or even give them food. He was the employee who allegedly yelled at a co-worker while waving an ax in 2005.

Some employees interviewed by the department denied seeing evidence of misconduct. A longtime friend of Boatman 3 and the supervisor said that the men were “free spirits” and that women were at fault for being “scantily clad” and flirting with their male colleagues.

Writing in an email to the AP, one of the woman who took part in the 2014 complaint said that the report was a good first acknowledgement of the problem, but that most of the proposed changes were trivial.

“It was a culture of victim-blaming perpetuated by all levels of management,” she said. “I repeatedly sat in meetings in which victims who had reported sexual violence were degraded and discredited.”