PONDEROSA BASIN -- Lightning-sparked fires spread across southern Mariposa County on Monday, prompting concerns about evacuations and placing firefighters at every driveway on a dirt mountain road.
The Mariposa County fires had burned more than 960 acres in steep terrain by 7 p.m. Monday.
The largest, the Oliver Fire, had grown to more than 500 acres and was hovering menacingly above residents on a dirt portion of Chowchilla Mountain Road that bordered U.S. Forest Service land. Firefighters were stationed at individual driveways to defend homes.
The fires ignited Saturday during a thunderstorm that caused more than two dozen lightning strikes in the Sierra National Forest, said Trudy Tucker, a public affairs specialist for the Bass Lake Ranger District.
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Janet Snyder, a part-time resident in Ponderosa Basin, said the Saturday rain was a nice change, but then came the fire. She said Mariposa County sheriff's deputies arrived at 8 a.m. Monday and suggested that she prepare for evacuation. Later Monday, she was waiting for more fire information and was pondering whether to leave.
"There are a few pictures and some papers," she said. "We have insurance."
Snyder said she has been evacuated once before because of fire, near her other home in Burbank.
But, in 20 years in Mariposa County, she said, "There has never been one this close."
Patty Arfsten, who arrived home Monday after being away for a few days, said she was concerned because she had never seen a fire during her 20 years on Chowchilla Mountain.
"It's jumped one ridge, gone down a ravine and it's coming down the last ridge," she said.
Mariposa County Fire Chief Jim Wilson said the fire appeared to be getting closer to some residents, but there was no wind to push the slow-moving blaze.
Evacuation was mandatory on a small portion of Standard Mill Road and one couple left their home Monday, Wilson said.
Residents in Ponderosa Basin have been fortunate for the past 50 years because there have been very few fires there. But a lack of fires has added more timber and brush, more fuel for a fire to burn, he said.
"There are some pretty heavy fuels," Wilson said. "Our objective is to box the fire in."
He said firefighters were more concerned Sunday with the Westfall Fire, fearing it could overrun the mountain community of Fish Camp. But the winds died off. By Monday afternoon, the fire had burned 60 acres and was 40 percent contained.
A third Mariposa County fire, the Silver Knob Fire, had scorched about 400 acres near Cedar Brook. By 8:30 p.m. Monday, it was 10 percent contained.
Smoke from the Mariposa County fires and other California fires drifted into the San Joaquin Valley, leading the region's Air Pollution Control District to issue a "cautionary statement" for people sensitive to bad air. The smoke brought increased levels of particulate matter and ozone pollution to the Valley, said Shawn Ferreria, a senior air quality specialist with the district.
The air quality for most of the district was "unhealthy for sensitive groups" Monday and is forecast to be the same today, he said. People with heart or lung disease are at risk, and others are warned to avoid prolonged exposure.
Hundreds of small fires were burning Monday across California, caused by wind and lightning in the mountains and deserts, Gov. Schwarzenegger's office said. Schwarzenegger directed the California National Guard and state firefighting operations to help, including more than 4,000 Cal Fire personnel.
"It's been a really dry spring," said Matt Shameson, a fire-weather meteorologist with the Forest Service in Riverside. Trees, grass and other "fuels" for fire are more likely to ignite because of the lack of rain, he said.
Thunderstorms were responsible for as many as 75 fires in Shasta-Trinity National Forest, about 160 miles north of Sacramento, the Associated Press reported. Fires ranged in size from less than an acre to more than a square mile. None immediately threatened homes, said Forest Service spokesman Michael Odle.
Mendocino County had as many as 90 fires, charring a total of 5,000 acres, Cal Fire officials said.
A fire that began Friday in Santa Cruz County destroyed homes and closed a stretch of highway. It contained after charring just less than a square mile. Evacuation orders were lifted Saturday, a day after roughly 2,000 people fled their homes.