Fire crews spent Thursday protecting structures in Rocky Bar and Dutch Creek from the fast-moving Trinity Ridge Fire near Atlanta and warning recreationists to clear out of the area.

At its north edge, the fire jumped the Middle Fork of the Boise River and destroyed several Forest Service cabins. In all, seven structures were lost.

On the south, where the fire is moving toward the historic community of Rocky Bar, firefighters set up a network of sprinklers to keep the ground and buildings wet.

“They make it rain,” said Steve Hardwick, who lives about 200 days a year in what was once the house of a Chinese storekeeper. He and his wife, Gail Ann, said they appreciate the crews’ efforts to protect their tiny, remote mountain community, where some of the existing buildings survived the last Rocky Bar fire — in 1892.

“We don’t plan on leaving until they tell us,” says Steve.

Since Wednesday, Forest Service employees have been in the backcountry between Arrowrock Reservoir and Atlanta — which includes Featherville and Graham — looking for campers, horse riders and motorcyclists and informing them they must leave.

Law enforcement officers are at busier forest roads — such as the intersection of Edna Creek and North Fork Boise River roads — to make sure people don’t enter the closed area, officials said Thursday. Signs are being posted on some of the region’s many forest roads. Officials also left notes on cars when they couldn’t locate hikers and backpackers.

It is unclear how long the closure will last.

Failing to heed the closure order is a misdemeanor punishable by up to six months in jail and a $5,000 fine. But fire officials said everyone they’ve encountered has been cooperative.

EXPLOSIVE GROWTH

The Trinity Ridge Fire was sparked Friday east of Idaho City by a burning utility vehicle (similar to a golf cart).

Fire officials warned that the blaze had potential for rapid growth because of dry conditions, steep terrain and an abundance of timber.

On Tuesday, the fire was estimated to be about 3,000 acres. By Wednesday afternoon, it had grown to 17,000 acres, stoked by high temperatures and winds, fire officials said. By Friday morning, it had grown to 30,000 acres.

SPRINGS FIRE NEAR BANKS

Firefighters continue to battle the 3,500-acre Springs Fire along the Banks to Lowman Highway and Idaho 55. It was ignited Sunday near Skinnydipper Hot Springs.

Idaho 55 just north of Banks was reopened to traffic Thursday after being closed since Tuesday because of falling rocks.

Motorists still endured traffic delays on the Banks to Lowman Highway as crews worked to put out flames. Motorists are warned to watch out for rocks and other debris.

The fire advanced north, crossing the Zimmer Creek area about 5 miles north of Banks. The Springs Fire jumped the South Fork of the Payette Tuesday night and continues to burn up the ridge.

On the north, the fire burned about half a mile from the 18-home Frazier Creek subdivision. No structures had burned as of Thursday night. About 240 firefighters, helicopters and planes are working the fire.

STANLEY-AREA FIRES

The new Bench Fire broke out about 3 p.m. Thursday along Idaho 21 near Banner Summit.

Idaho 21 between Grandjean Road at milepost 93.75 and the Elk Meadows turnoff at Iron Creek Road at milepost 122 (about 7 miles west of Stanley) was closed Thursday as the fire burned on both sides of the highway.

Crews from the nearby Halstead Fire responded to the fire, which started near the Bench Creek campground and was listed at 75 acres as of 5:30 p.m.

The Halstead Fire has grown to nearly 37,000 acres. About 390 people are working the fire, ignited by lightning July 27. An emergency closure has been in effect since Aug. 3 for the Cape Horn area.

Patrick Orr: 377-6219, Twitter: @IDS_Orr.

Katherine Jones and Cynthia Sewell contributed.