WASHINGTON – Park rangers, wildlife refuge workers and U.S. Park Police experienced more assaults and threats from visitors last year than in 2011, according to a group that represents federal resource workers.

Six land and water agencies reported a total of 591 incidents in 2012, up 38 percent from the previous year, the group says. More than one-quarter of the incidents involved some sort of violence against the employee or officer, the report by the advocacy group Public Employees for Environmental Responsibility says.

More than half of 100 reported incidents against U.S. Park Police involved violence, the report said, including an incident where a suspected drunk driver tried to run over a police officer.

The report is set to be released on Monday. The Associated Press obtained a copy in advance. The report is based on figures obtained from the National Park Service, Bureau of Land Management and other agencies.

The report says 2012 began violently, with the New Year’s Day shooting death of a park ranger at Mount Rainier National Park in Washington state, the first ranger killed in the line of duty in a decade. That same month, a note was a left at a Texas wildlife refuge visitor center that included racist remarks and a threat to burn down the center. In September, someone took a shot at a land management worker driving an agency vehicle at an Arizona recreation area.

Other incidents include assaults on law enforcement officers, resisting arrest and threats of violence, including at least one that resulted in a court-imposed restraining order.

Jeff Ruch, executive director of PEER, said the report shows that incidents of violence and abuse directed against rangers and other federal employees are becoming more common.

“The saying ‘It’s not easy being green’ is becoming truer with each passing year,” said Ruch.