A September report by the Sierra Nevada Conservancy shows that the Central Subregion, of which El Dorado County is part of, has more than half of the acres in the subregion being of “high and above” threat.
The report, “Fire Threat,” by lead author Mark Stanley with data analysis by Steve Beckwitt, shows that of the approximately 25.5 million acres of the forest in the state, about 17.5 million acres are categorized as “high and above” for fire threat, or about 68 percent of the forest. Of the 2.5 million acres in the Central Region, comprised of parts of El Dorado, Placer, Nevada and Yuba counties, 1.7 million acres, about 67 percent, is “high and above.” The simple definition of fire threat, the report says, is “the possibility of a fire occurring based on the history of fire occurrence and the potential damage based on the behavior a fire may exhibit.”
Cal Fire tracks the areas in four classes: Extreme, very high, high and moderate. There is also non-fuel, meaning there is little to no threat. The report notes that high and above are grouped together as they are, as far as the SNC is concerned, functionally the same.
Subregions across the state have high fire threats, the report reads. “The North, North Central and South Central Subregions average about 75 percent in the high and above fire threat classes, while about two-thirds of the Central and South Subregions is in that threat range … The landscape of the Central Subregion, which contains the bulk of the region’s population, has been much more modified than other subregions. The South Subregion is likely at slightly lower overall threat because it has the highest elevations and contains the most area at little or no fire threat, which is primarily high alpine terrain with little vegetation. The large area of national park land is the south may also play into the figures. Only 48 percent of the East Subregion is in the high and above threat range, due mostly to lack of heavy vegetation to carry large fires due to dry conditions on the east slope of the Sierra and in the Owens Valley.”
The Central Subregion contains the highest amount of wildland urban interface, or WUI, of all the subregions. About 640,000 acres, or about 25 percent of the total acres in the subregion, is WUI. Of that, about 541,500 acres, or 85 percent, are in the high and above threat range. The Central Subregion accounts for 39 percent of the total WUI in the region.
“The portion of Sierra wildfire that occurs each year that is in the WUI is generally fairly small … in a typical year since 1998, 1 to 3 percent of total land burned in the Sierra is in the WUI. The one major exception in the past 15 years was 2004, when nearly 10 percent of the burned acreage was in WUI, though this was overall a modest fire year.”
Last year, about 475,000 acres in the Sierra Nevada Region burned; of that, only 1,075 acres were in the WUI, or 0.23 percent. Despite this, the Central Subregion’s WUI has not been affected much by fires, and “the cumulative amount of WUI burned over the past 15 years has actually been less than some of the other Subregions, and certainly a much smaller percentage of the WUI than any other Subregion.” Just under 7,000 acres of Central Subregion WUI burned between 1998 and 2012, more than only the South and East Subregions.
Changing climate in the Sierra Nevada Region has not helped with fire threats.
“Restoring the health of the forest and reducing fire threat will take a significant amount of time (most likely decades) and increased investment,” the report concludes. “These Fire Threat Indicators can help us track the progress that is being made in terms of on-the-ground efforts to improve forest conditions and reduce fire threat over time and help inform strategic investment.” A methodology is currently being developed to that end, to help characterize and track the severity of fires in the future.