Officials say full containment estimated for Aug. 10
Mammoth’s battle with some of the worst air quality in recent history appears to be slowly coming to an end.
By Thursday morning afternoon, the Aspen Fire had grown to about 16,205 acres, and had a fire line around about 40 percent of it— a far cry from the earlier part of the week when the fire was under 10 percent contained.
There were about 1,940 firefighters assigned to the fire, and it has so far cost about $12.9 million.
Although fires and weather are unpredictable and the fire could still blow up again, fire officials say a turning point may have been reached.
“We finally got a handle on the northeast corner for the first time, and that’s the place where we have been struggling the most,” said Deb Schweitzer, the Inyo National Forest’s public information officer.
“The terrain, the weather—everything has combined to make it an especially hard fire to fight safely.”
The latest estimate for full containment is Aug. 10, she said, and that will occur only if certain firefighting techniques are successful-—and the weather cooperates.
She said the Aspen Fire, burning in very steep, granite canyons covered in heavy timber and dense brush near Big Creek and Huntington Lake on the west side of the Sierra crest, has also been plagued by weather patterns which made it hard to fight the big fire in the traditional way—with heavy aircraft fire retardant drops.
“The inversion has trapped smoke in the lower areas of the fire and made it hard to see for both aircraft and firefighters,” she said.
Mammoth and the Eastern Sierra, while not in danger from the fire itself, have paid a high price for the same weather pattern.
Predominately west winds have pushed tremendous quantities of smoke from the fire—which is about 40 miles directly west of Bishop and Aspendell—straight toward Mammoth and Bishop. A high-pressure ridge hovering over the Central Sierra has trapped the smoke flowing over Mammoth Pass and other passes between the fire and the Eastside, National Weather Service officials said.
The end result has been at least one 24-hour period of air pollution that exceeded federal standards for the first time since Mammoth began to replace all of its ancient, polluting wood-burning stoves with modern stoves in the early 1990s, said Ted Schade, the director of the local air pollution control district.
Air pollution is measured by the number of a certain size of pollutant particles in the air at a given time, or “hourly particulate pollution” (also called PM10), is measured in micrograms per cubic meter of air.
The federal standard is set at 150 micrograms, averaged over a 24-hour period.
Mammoth exceeded that several times, Schade said on Tuesday.
“Mammoth PM10 24-hour average values exceeded the federal standard each of the last two days,” he said. “It was 166 on July 28, and 183 on July 29. These are the first federal exceedances in Mammoth since the early 1990s.”
In the case of a carefully controlled “prescribed burn” fire, where firefighters have the luxury of increasing or decreasing fire activity, smoke pollution numbers that violate the federal standard would be enough to trigger Schade and Great Basin Unified Air Pollution Control District officials to ask fire managers to back off on smoke production.
“We would be having a fit,” Schade said. “We would begin to put pressure on them to cut back.”
But the Aspen Fire is an uncontrolled wildfire.
“The air pollution control district over there is dealing with the same thing,” he said. “Everyone is motivated to get this fire out as soon as possible.”
Even as firefighters appear to be gaining the upper hand, smoke is likely to continue to flow over Mammoth Pass and other passes for the next several days, according to Shane Snyder, a meteorologist for the National Weather Service.
“There is a high pressure ridge over the Four Corners area that is keeping this southwest flow aloft,” he said. “This is not going to change very much for several more days and into the weekend, at least. It’s now a matter of them getting a hold on this fire.”
Local health officials say the best thing to do to deal with the smoke is to limit activity during periods of heavy smoke as much as possible.
For those who must work in the smoke, a wet cotton handkerchief has been found to be more effective than any other alternative, said Dr. Rick Johnson, the public health officer for Mono and Inyo County.