MATTAWA — A Grant County wildfire that threatened homes and farms near Mattawa is now 65 percent contained, authorities said.

People in more than a dozen homes and businesses had been evacuated and others warned to be ready to evacuate.

The blaze, which is being called the Powerline fire, began just after 12:30 p.m. Sunday. By Tuesday morning, the fire had spread to about 7,800 acres (about 12.2 square miles), according to the Southeast Washington Interagency Incident Management Team. The blaze is about 65 percent contained.

“The weather this morning was overcast, the winds were calm and we did get some precipitation, and that has been really helpful for the crews out on the ground,” said spokeswoman Nancy Jones Monday evening. “Yesterday afternoon, it was very windy. The field was just dry grasses and brush. When you get those conditions, the fire just runs. It goes fast.”

Firefighters are struggling with a manure pile that has been particularly difficult to extinguish, Jones said.

“You’ve got this huge pile of compact materials that’s smoldering, and if you just put water on it ... it wouldn’t penetrate it,” she said. “I’m not sure that’s something that’s ever been dealt with before.”

The Sheriff’s Office wrote in a Facebook post Sunday that the fire is burning sagebrush and grasslands on steep terrain with no safe access for firefighters. No homes or other structures have been lost, but people in 15 homes and business have been told to evacuate and others have been told to be ready to evacuate; the exact number of people affected is unknown, according to the post.

“If you are not a resident of that area or if you are not assisting a resident of that area, stay off the roads,” the Sheriff’s Office wrote.

Ten power poles destroyed by the fire were replaced Monday by the Grant County PUD, according to the interagency team.

The cause of the fire is under investigation, according to the State Fire Marshal’s Office, a bureau of the Washington State Patrol.

The State Patrol has authorized four strike teams from the Fire Protection Bureau to help Grant County firefighters try to contain the blaze.

More than 20,000 acres of Grant County burned last month in the state’s first big wildfire of the year, the 243 fire. About 25 households were evacuated then, but no homes were lost.

Wenatchee World reporter Pete O’Cain contributed to this report.

___ (c)2019 The Seattle Times Visit The Seattle Times at Distributed by Tribune Content Agency, LLC.