Despite stubborn heat and wind over the Labor Day weekend, firefighters battling the Rim fire burning into Yosemite National Park tightened their grip around the historic blaze and turned their focus to what caused it.

The fire started in the Stanislaus National Forest on Aug. 17 and is burning into neighboring Yosemite National Park. It has chewed through 235,841 acres, or 368 square miles. The fire was 75% contained Tuesday.

Full containment isn’t expected for two weeks — the area burned is larger than Dallas or San Diego — and investigators aren’t sure what started it. But the fire chief in the small, nearby mountain town of Twain Harte, named after authors Mark Twain and Bret Harte, told an audience of community members days after the blaze broke out that he’s sure the Rim fire is man-made.

“We know it’s human-caused,” Twain Harte Chief Todd McNeal said at the Aug. 23 meeting. “But we don’t know the exact cause. It’s highly suspected it might have been some sort of illicit grow, marijuana-grow type of thing.”


The fire started at Jawbone Ridge north of the Tuolumne River, an area that McNeal said has “zero foot access” and had no recent lightning strikes. Anyone trying to reach the area would have to be dropped in by air or trek up the mountain from the river, McNeal said. An employee at the Twain Harte fire station said Tuesday that McNeal was out fighting the fire and was unavailable for comment.

Authorities have said throughout the battle with the Rim fire that the terrain has been dicey in some parts, completely inaccessible in others.

For their part, U.S. Forest Service officials said investigators have made progress toward determining the fire’s cause, but wouldn’t elaborate. More than 5,100 firefighters were fighting the flames at the blaze’s peak. About 4,300 remained in the area Tuesday.

“We’re making good progress,” said Daniel Berlant, a spokesman for the California Department of Forestry and Fire Protection. “We’re definitely seeing the tables turn as we advance toward total containment.”


All evacuations on the north end of the fire off California 108 in Tuolumne County were lifted at noon Tuesday and winds that pushed a blanket of smoke and haze over the Yosemite Valley over the weekend were expected to shift this week.

The Rim fire has destroyed 111 buildings, including 11 residences. It has cost $72 million to fight so far. Though the fire’s size is extraordinary, the conditions that caused it are not, Berlant said. The coming months are California’s typical fire season where, despite shorter days and longer nights, drier air and stronger winds spell disaster.

“If it’ll burn this well in August, think about things in September when things are drier and then we see the wind,” Berlant said. “This fire really showed us just how dry the timber is at higher elevations.”

Last month, Gov. Jerry Brown declared a state of emergency for the city and county of San Francisco because of the Rim fire’s threat to the Hetch Hetchy reservoir, which serves millions of Bay Area residents. On Tuesday, Tuolumne County residents and business owners announced their own concerns.


“If heavy rain and snow comes this winter, we could see the wild and scenic Tuolumne running brown instead of clear,” Patrick Koepele, deputy executive director of the Tuolumne River Trust, said in a statement.

The river is a draw for rafters, anglers and species that could be affected by the charred sediments that may fill the water this winter.

joseph.serna@latimes.com

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