More than 750 firefighters backed by air support are battling three lightning-caused wildfires in southwestern Oregon.

More than 750 firefighters backed by air support are battling three lightning-caused wildfires in southwestern Oregon.

The largest is the 625-acre Horse Mountain fire on the Wild Rivers Ranger District in the Rogue River-Siskiyou National Forest about 17 miles southwest of Grants Pass. More than 460 firefighters have been deployed just east of the Illinois River.

Nearly 300 firefighters are on the higher elevation 500-acre Lonesome complex fire near the Rogue-Umpqua Divide on both the Rogue River-Siskiyou and Umpqua national forests. The complex is made up of three different fires in the vicinity.

Firefighters and equipment also are deployed to the 150-acre Bessie Rock fire about eight miles east of Prospect.

All the fires were sparked by lightning on Aug. 16. More than 40 smaller lightning-caused fires in the region have been snuffed out.

However, fire officials are concerned the mercury is expected to rise following an unusual cool but short August weather pattern, spurring more aggressive fire behavior.

"Suppression efforts have been successful over the last few days," said Tom Suwyn, who heads the effort to stop the Horse Mountain fire. "Safety remains our first priority as firefighters continue work. We appreciate the patience of the community as our work continues."

The Lake Selmac park and campground in Selma is closed to provide a base for the firefighters. Travel restrictions may also be imposed on Illinois River Road as a safety precaution because of the fire vehicle traffic, officials said.

Containment for the Horse Mountain fire is about 35 percent. In addition to the firefighters, five helicopters, 12 fire engines, one bulldozer and two water tenders are deployed to the fire.

Over at the Lonesome complex on the far northern end of the High Cascades Ranger District, eight fire engines, four water tenders and three heavy helicopters have been deployed to help the ground pounders.

The fire camp is based at the Jim Creek Seed Orchard. Officials warn of heavy fire vehicle traffic on Forest Road 68 in the Woodruff Bridge area.

The Lonesome fire is spreading slowly across the Rogue-Umpqua Divide, according to fire spokesman Paul Galloway.

Minimum impact suppression techniques will be employed by firefighters to reduce the impact on the ground and natural features, he said. Natural features such as rock outcroppings and wet meadows will be used to halt the spread of the fire, he added.

Reach reporter Paul Fattig at 776-4496 or e-mail him at pfattig@mailtribune.com.