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WASHINGTON — Sexual harassment, bullying and other misconduct is rampant among employees at national parks across the country, including at iconic sites such as Yosemite, Yellowstone and the Grand Canyon, a congressional committee was told Thursday.

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 Yellowstone, officials are investigating complaints of sexual exploitation, intimidation and retaliation.

The complaints follow a report by the Interior Department's inspector general that found male employees at the Grand Canyon preyed on female colleagues, demanded sex and retaliated against women who refused.

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In a separate case, the park service has temporarily reassigned the superintendent of a Florida park where female employees long complained of sexual harassment and a hostile workplace.

"There seems to be some patterns here that are just not anything we should come close to tolerating," said Rep. Jason Chaffetz, R-Utah, chairman of House Oversight and Government Reform Committee.

Michael Reynolds, deputy director of operations for the National Park Service, acknowledged problems at many of the agency's 413 park sites, including the Grand Canyon and other parks visited by millions of people each year.

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Norris Geyser Basin in Yellowstone National Park, Wyo. in 2009. Beth Harpaz / AP file

Problems at the Grand Canyon and also the Canaveral National Seashore in Florida "were more than a wake-up call," Reynolds told lawmakers. "They presented us with clear and undeniable evidence that ... we must extend the same commitment to the employees of the National Park Service as we make to the protection of our nation's most extraordinary places."

Asked if he agreed the agency has a problem with harassment and hostile work environments, Reynolds said yes.

Kelly Martin, Yosemite's chief of fire and aviation management, told lawmakers that she has been sexually harassed throughout her 32-year career at the park service and U.S. Forest Service.

Early in her career, a Grand Canyon park ranger stood outside her bathroom window and watched her shower, Martin said. After she reported the incident, he apologized and no further action was taken. The ranger "was repeatedly caught engaging in voyeuristic behavior, all the while receiving promotions around the agency until his recent retirement as a deputy superintendent" at a national park, Martin said.

At Yosemite, dozens of people, mostly women, "are being bullied, belittled, disenfranchised and marginalized from their roles as dedicated professionals," Martin said. She and other employees said Park Superintendent Don Neubacher has "publicly humiliated" workers, intimidated them and questioned their professional credibility.

Yosemite employees described "horrific working conditions (that) lead us to believe that the environment is indeed toxic, hostile, repressive and harassing," the park service said in a preliminary report last month.

Chaffetz and other lawmakers said problems at Yosemite are exacerbated because Neubacher's wife, Patricia Neubacher, is deputy director for the Pacific region, which includes Yosemite.

Scott Gediman, a spokesman for Yosemite, declined to comment, referring questions to the agency's Washington headquarters

Spokesman Jeremy Barnum said the park service is implementing "a comprehensive plan to identify and stop harassment, educate our staff at all levels about their rights and responsibilities, and create a safe and respectful work environment for every employee."

The agency has set up a hotline for complaints, improved training and is conducting a survey of employees, Barnum said.

Park Service Director Jonathan Jarvis "has made clear to all NPS employees that when incidents of harassment are reported, NPS managers must take the allegations seriously ... and act promptly to ensure the harassment ... does not continue," Barnum said.

If allegations are verified, "disciplinary action will follow," he said.

Rep. Elijah Cummings of Maryland was dubious, noting that an agency task force reached many of the same conclusions 16 years ago.

"Sixteen years later, allegations have been made at Yosemite and Yellowstone national parks about possible harassment, hostile work environments and even sexual exploitation," Cummings said.