The massive Rim fire burning into Yosemite National Park is now 75% contained, the U.S. Forest Service said Tuesday morning.
Forest Service officials listed the Rim fire’s burned acreage at 235,841 acres, or roughly 368 square miles, making it the fourth largest in state history. A September 1932 fire in Ventura County that burned 343 square miles previously held the spot, according to Cal Fire.
About 5,000 firefighters are battling the blaze, according to the U.S. Forest Service.
Officials warned that smoke from the Rim fire, which started Aug. 17, was beginning to settle over Yosemite Valley, Wawona, Foresta and other areas, causing "air quality impacts," the Forest Service reported. Smokey conditions are expected to persist for the next few days.
Wind shifts on Friday dumped smoke into the Yosemite Valley, which appeared hazy with decreased visibility on video streaming from webcams in the park. Southwest winds Tuesday are expected to clear the valley and push the haze toward the Lake Tahoe basin.
Meanwhile, there has been a noticeable decline in visitors to the park, said Yosemite National Park spokeswoman Kari Cobb, partly because of the fire's smoke but also because of road closures in the park.
Park officials are advising visitors to avoid strenuous activity and for those sensitive to smoke to avoid being outside.
The Rim fire has destroyed 111 structures, 11 of them residential, and is expected to be contained Sept. 20, said California Department of Forestry and Fire Protection spokesman Daniel Berlant. No structures inside the national park have been lost, Cobb said.
Battling the blaze, the largest in California this year, has cost $60 million in state and federal funds, U.S. Forest Service spokesman Trevor Augustino said.
Six other fires are burning in California, down from about a dozen last week, with more than 8,000 firefighting personnel deployed across the state, Berlant said. There has been an increase in fire activity in recent weeks, he said, because of dry conditions, gusty winds and dry lightning that sparked several hundred fires.
Investigators are still trying to determine what caused the Rim fire, Augustino said, adding that progress had been made in the case but no additional details were available.
On Aug. 23, Gov. Jerry Brown extended a state of emergency to include the city and county of San Francisco because of a threat to utilities. Since the fire began, water quality at the Hetch Hetchy reservoir, which serves customers in the San Francisco Bay Area, is unchanged, according to the San Francisco Public Utilities Commission.
The fire has forced the shutdown of two of three hydroelectric power station transmission lines that carry power to the San Francisco area.
There are no mandatory evacuations or advisories for Mariposa County, but an advisory remains in effect for Ponderosa Hills and areas east along California 108 to Pinecrest. California 120 at the Yosemite National Park west to Buck Meadows has been evacuated.
ALSO:Copyright © 2015, Los Angeles Times