Burned plants are shown on a hill near Clearlake, Calif., Aug. 5, 2015.
Burned plants are shown on a hill near Clearlake, Calif., Aug. 5, 2015.

The tally of property losses from California's largest and most destructive wildfire this year nearly doubled on Wednesday as the week-old blaze raged through dry scrubland north of Napa Valley wine country.

The higher damage figures from the California Department of Forestry and Fire prevention (Cal Fire) coincided with an ominous U.S. Forest Service report that more than half its total budget is, for the first time, being spent on fire suppression across the country.

The agency's rising expenditures reflect an extraordinary wildfire season experienced this summer in California and several other Western states — including Oregon, Washington, Idaho and Alaska — in the midst of a widespread and prolonged drought.

Cal Fire crews have responded to more than 4,200 wildfires large and small so far this year, about 1,500 more than average.

Properties destroyed by the Rocky Fire is seen nea
Properties destroyed by the Rocky Fire is seen near Clearake, California, August 5, 2015.

The fiercest of some two dozen large blazes currently raging across state is the so-called Rocky Fire, which has charred nearly 70,000 acres since erupting July 29 in the foothills and canyons east of the town of Clearlake, about 110 miles north of San Francisco.

The fire has so far reduced 91 structures to ash - 39 homes and 52 outbuildings — up from the 50 structures previously counted as destroyed, Cal Fire reported on Wednesday. The agency warned that the toll of property losses may climb higher still as damage-assessment teams reach more recently burned areas.

On Wednesday, nearly 7,000 structures, mostly dwellings, remained listed as threatened, with some 13,000 people placed under evacuation orders or advised to leave their homes.

Portions of two major state highways in the area are closed.

The containment level for the blaze, a measure of how much of the fire's perimeter has been corralled by natural barriers or within buffer lines carved by ground crews, rose to 30 percent, up from 20 percent the day before, even as the flames devoured another 2,500-plus acres of landscape, Cal Fire said.

Stretching resources

A steadily increasing firefighting force of nearly 3,500 personnel was assigned to the Rocky Fire as of Wednesday, representing more than a third of the 10,000-plus firefighters on front lines statewide.

California firefighter Bo Santiago watches a backf
California firefighter Bo Santiago watches a backfire as the Rocky fire burns near Clearlake, California, Aug. 3, 2015.

Rocky Fire crews were backed by more than 60 bulldozers, plus a squadron of 19 water-dropping helicopters and four airplane tankers attacking the flames from the air.

Smoke from the fire has been visible up to 80 miles to the south, in the famed wine-making Napa region.

No serious injuries have been reported, but a Forest Service ranger died last Thursday in a smaller fire in the Modoc National Forest near California's border with Oregon.

National forest areas accounted for 14 of the 23 large, active fires reported burning in California on Wednesday.

With wildfire season becoming more of a year-round threat across the West, firefighting costs are projected to soar to two-thirds of the Forest Service budget within a decade, potentially diverting hundreds of millions of dollars from programs to help prevent blazes, the agency said in its report.

The Forest Service, which oversees more than 190 million acres of forests and grasslands, mostly in the West, expects to spend about $1.2 billion in the current fiscal year to fight fires, or 52 percent of its budget, the report said.

Fire seasons today are 78 days longer than they were during the 1970s, and at least 10 states have experienced their largest fires on record since 2000, the agency said.

Growing development near forest land is also a factor, with more than 46 million homes now at risk from U.S. wildfires, the report said.