A wolf pack in northeastern Washington recently associated with a fourth confirmed attack on livestock since September – despite the presence of range riders – has triggered a protocol that authorizes lethal removal, the Washington Department of Fish and Wildlife announced Thursday.

Agency director Jim Unsworth has authorized killing of wolves in the Smackout Pack of Stevens County, the agency said on its website.

The authorization calls for an incremental removal of pack members starting this week. If the pack’s livestock-attacking behavior is changed by killing a few wolves, the rest of the pack would be spared, officials said.

The last estimate of the Smackout Pack’s size from the 2016 winter survey was eight wolves. The pack has produced an unknown number of pups this spring.

Likely options for lethal removal include shooting from a helicopter, trapping, and shooting from the ground, officials said.

The department’s policy allows removing wolves if they prey on livestock three times in a 30-day period or four times in a 10-month period, said Donny Martorello, WDFW’s lead wolf manager.

That policy was developed last year by WDFW and its 18-member Wolf Advisory Group, which represents the concerns of environmentalists, hunters and livestock ranchers.

“Based on the information provided by the Department, it is clear that the ranchers involved in this case have been doing everything possible to avoid conflicts with wolves and other predators,” said Western Washington-based Conservation Northwest in a statement.

The statement said the group is saddened by the loss of livestock and the potential loss of wolves, but supports the guidelines that trigger lethal removal as a last resort.

The Smackout Pack is one of 20 confirmed packs in Washington.