The massive forest fire that has scorched 348 square miles in and around Yosemite National Park may have been sparked by illegal marijuana growers, according to one fire official in Tuolumne County.
The San Jose Mercury News reports that Todd McNeal, chief of the Twain Harte Fire Department, told a community meeting that it was "highly suspect that there might have been some sort of illicit grove, a marijuana-grow-type thing."
McNeal, who has 23 years of experience with Forest Service, the National Park Service and other agencies, said at the Aug. 23 meeting that investigators know the fire is human caused since there was no lightening in the area.
The fire started Aug. 17 and its exact cause remains under investigation. It is expected to keep burning long after it is fully contained, and recovery will be extensive. Some 7,000 damaged trees next to power lines will need to be removed by utility crews and 800 guardrail posts will need to be replaced on Route 120, a fire fact sheet said.
The blaze was 40 percent contained by Saturday evening and some small communities in the mountainous area were no longer under evacuation advisories, but smoke descending down into San Joaquin Valley cities was becoming a problem.
In a sign of progress, a few dozen firefighters were released and more could be sent home in coming days, said Daniel Berlant, spokesman for the California Department of Forestry and Fire Protection. More than 4,800 firefighters remained on the scene late Friday.
"We continue to gain the upper hand, but there's still a lot of work to be done," Berlant said.
The 2-week-old blaze burning in the Sierra Nevada northeast of Fresno has grown to become the largest U.S. wildfire to date this year and the fifth-largest wildfire in modern California records.
Winds had been blowing dense smoke plumes northeast into the Lake Tahoe area and Nevada but a shift Friday brought them west down to the San Joaquin Valley floor.
Regional air pollution control authorities issued a health caution for San Joaquin, Stanislaus, Merced, Madera, Fresno and Tulare counties. Residents who see or smell smoke were urged to stay inside, especially people with heart of lung problems, older adults and children.
Evacuation advisories were lifted Thursday in Tuolumne City, Soulsbyville and Willow Springs but remained in place for other communities, and evacuations were still mandatory along the fire's southeastern edge.
About 75 square miles of the fire are inside Yosemite but at some distance from the national park's major attractions, including glacially carved Yosemite Valley's granite monoliths and towering waterfalls.
Park officials expect about 3,000 cars a day to pass through gates during the long Labor Day holiday weekend instead of the nearly 5,000 that might typically show. The fire has caused some people to cancel reservations in the park but those vacancies have been quickly filled, officials said.
"Valley campgrounds are still full and skies in Yosemite Valley are crystal clear," said park spokeswoman Kari Cobb.
A 4-mile stretch of State Route 120, one of three western entrances into Yosemite, remained closed, hurting tourism-dependent businesses in communities along the route.
Costs reached $47 million, including firefighters from 41 states and the District of Columbia and significant aviation resources including helicopters, a DC-10 jumbo jet and military aircraft equipped with the Modular Airborne FireFighting System. Aircraft have dropped 1.7 million gallons of retardant and 1.4 million gallons of water.
The Associated Press contributed to this report.