BILLINGS, Mont. — Government investigators were expected to visit Yellowstone National Park to look into an employee’s claims of sexual exploitation of female workers and financial misconduct, park officials said.

The visit Tuesday is part of an investigation by the inspector general of the U.S. Interior Department following reports of widespread sexual misconduct at national parks such as Grand Canyon and Yosemite, where the superintended has apologized to his staff in an email.

In Yellowstone, the sexual exploitation of female employees has been rife in the park’s special projects division, which does construction and maintenance, equipment operator Robert Hester said in a statement submitted last week to the U.S. House Oversight and Government Reform Committee.

In one case, a supervisor kept a young female worker drunk and she was in effect paid to have sex, a situation that was common knowledge in the park, Hester said.

“From the date I started to work at the park, I was shocked and amazed at what I saw and heard in regard to the talk and acceptance of sexual exploitation of female workers,” Hester wrote.

He worked from 2010 to 2012 in the special projects division, which Hester described as being like a “men’s only club.” He now has a permanent job as an engineering equipment operator at Yellowstone, which includes portions of Wyoming, Montana and Idaho and was the nation’s first national park.

The accusations also include misuse of government credit cards. Hester said he and another employee had been instructed to violate rules about purchasing repair parts and maintenance.

The investigation would focus initially on the special projects division and expand as needed, Yellowstone Superintendent Dan Wenk said Monday. He said no one else has stepped forward with claims similar to Hester’s.

Wenk initially planned to bring in outside investigators to eye the claims. Those plans were canceled when the Inspector General’s Office stepped in, he said.

Hester’s complaints follow an inspector general’s report that found male employees at the Grand Canyon preyed on female colleagues, demanded sex and retaliated against women who refused.

At Yosemite, at least 18 employees have come forward with allegations of harassment or other misconduct so severe that a recent report labeled working conditions at the park “toxic.”

At Florida’s Canaveral National Seashore, the park superintendent was recently reassigned after female employees had long complained of sexual harassment and a hostile workplace.

Hester could not be immediately located for comment. His accusations were first reported by Montana Pioneer magazine earlier this month.

During testimony last week before the House oversight committee, a senior National Park Service official acknowledged that the agency has a problem with harassment and hostile work environments.

Yet evidence obtained by lawmakers suggests the park service has not held people accountable for past incidents of sexual harassment, committee spokeswoman MJ Henshaw said.

It’s too soon to say if that’s the case for Yellowstone or if its alleged problems are on the same scale as events at other parks, Henshaw said.

Wyoming U.S. Rep. Cynthia Lummis said there’s no indication that Wenk was aware of the allegations and ignored them.

Inspector General’s Office Director of External Affairs Nancy DiPaolo said the government’s probe of events at Yellowstone will be unlimited.

“We’ll go wherever the leads take us,” she said. “At this point we’re looking into management issues at the park that run the gamut.”

Don Neubacher, superintendent at Yosemite, sent an apology Sunday in an email to all park employees, referencing “some serious staff concerns related to Yosemite’s workplace environment.”

Neubacher has been superintendent at Yosemite for nearly seven years, but he said he wasn’t aware of these problems until recently, which make him “deeply saddened.”

He said he has an open-door policy and encouraged employees to bring their concerns to him, their direct supervisor or another superior.

“If I did offend any of you at anytime, I want to sincerely apologize,” he said in the email, adding that he has strived to make Yosemite a positive workplace. “The concerns I just recently became aware of have only strengthened my resolve to reach that goal.”

AP Correspondent Scott Smith contributed to this story from Fresno, California.