Certain shrubs reach 'critical' moisture levels in Orange County

Aug. 31, 2010 | By Susan Valot | KPCC

Photo courtesy the Orange County Fire Authority

Firefighters drop retardant during the Santiago Fire in Orange County in 2007. The wind-driven wildfire destroyed a dozen homes.

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We’re heading into what should be the hottest and windiest time of year. Firefighters are closely watching the hillsides. That includes measuring moisture level in key types of vegetation. Last week, one type of bush reached "critical" levels in Orange County.

Every couple of weeks, Orange County firefighters measure the moisture levels of California sage, black sage and chamise. Those are the three major types of brush that carry wildfires in Southern California.

George Ewan is the Orange County Fire Authority’s wildland fire defense planner. He’s in charge of measuring the moisture by clipping samples at different locations, carrying them back to the office and putting them in a moisture analyzer. That analyzer cooks off the moisture.

"It basically is an oven – a high-tech oven – and it gives me the percentage of weight difference in the weights. And we can tell by that how little moisture is in the vegetation," says Ewan.

As of last Tuesday, the moisture in chamise hit "critical" levels in Orange County. Chamise are big bushes that sprout white flowers in the spring. Those flowers dry out and turn to a chocolate color by this time of year.

Ewan says that’s the dark brown you often see on the hillsides. He says the brown means it’s stopped growing.

"Even though it’s a living piece of vegetation, it will burn just as if it’s dead," Ewan says.

Ewan says this winter’s rain-followed-by-warm-weather pattern made the vegetation grow quickly.

Once that vegetation dries out, it could spell trouble when the Santa Ana winds hit.

Firefighters are urging homeowners to prepare for fire season now, if they haven't already. They suggest clearing brush away from the house, making sure vents and openings are covered with fireproof mesh and boxing up valuables and sentimental items to easily grab during an evacuation.

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