Even in a year marked by the loss of 19 elite firefighters’ lives in a single catastrophe, the blaze now moving through Yosemite National Park may become the 2013 fire season’s event best remembered for its teachings about the new face of wildland fire in the American West.
As of Thursday morning, the Rim fire that began 12 days earlier in the Stanislaus National Forest had grown to 192,737 acres, or more than 300 square miles.
For perspective, the city of Minneapolis covers fewer than 60 square miles. If a square covering the area of the Rim fire were laid over the Twin Cities, with its southeast corner at the State Capitol, the southwest corner would be somewhere in Wayzata, the northwest out beyond Maple Grove and the northeast somewhere between Lino Lakes and Forest Lake.
But size alone will not be the measure that ranks the Rim fire high on the list of historic wildfire events.
There is the threat to a major city — San Francisco being in a state of emergency for a week now, because of risks to both the water and hydroelectric power supplies flowing from the Hetch Hetchy valley. (Smaller, exurban communities are also threatened; more than 100 homes and other structures have burned already.)
There are the enormous costs of containment in a year when the U.S. Forest Service’s firefighting budget had been exhausted before the end of August, with at least two more months remaining in the fire season.
And there are signs of lasting ecological loss and disturbance from still another fire that burns more fiercely than its predecessors, this time in an area whose iconic features have made it well known to Americans far beyond the California border, and sometimes earned it special protections.
Water too clean to need filtering
Thanks to intensive watershed-management measures, the water that collects in the Hetch Hetchy reservoir and then flows 160 miles to the Bay Area is so pristine that the state of California exempts it from the usual requirement that drinking water be filtered (it does receive some chemical treatment, however).
As of Wednesday, ash was seen to be collecting on the surface of the reservoir, but that’s not the real problem. Wood ash is not the most terrible contaminant one could think of.
In any case it will take some time for ash in any quantity to sink 250 feet or more to the intakes that carry water through the O’Shaughnessy Dam and into the aqueduct that carries water to 2.6 million people, including all the households of San Francisco and 85 percent of households in the Bay area.
Water quantity issues, too
The real concern is what could happen to water quality in the months and years after the fire is done, as rainfall washes both ash and soil from burned-over areas into the reservoir. There is a water quantity concern, too, over the prospect that ash and silt might simply gum up the system.
The Christian Science Monitor dug below the surface of this question without really finding a definitive answer. It found a firefighting expert in Claremont, Calif., who pointed out that soil erosion after the Hayman Fire near Denver in 2002 required a two-year, $25 million cleanup program to get the dirt out of water supplies for Denver and Aurora.
However, a retired U.S. Forest Service researcher told the Monitor that, so far, fire has reached the edge of the reservoir by burning over areas where granite is close to the surface, with few trees and little soil above, and most of the heavily forested portions of the Hetch Hetchy watershed are likely to stay out of reach of the Rim Fire.
It’s worth noting that Gov. Jerry Brown’s emergency declaration last Friday was motivated less by concern about water supply than power supply.
Three hydroelectric stations are linked to the Hetch Hetchy reservoir and these generate electricity for San Francisco’s international airport, municipal buildings and principal public hospital. Two have been damaged by the fire already; one has been repaired.
Additional drinking water has already been banked in other reservoirs along the aqueduct system, and San Francisco has contracts that allow it to draw on other cities’ supplies if that becomes necessary. Make-up electricity is harder to come by.
Parallels and departures from norm
In many ways the Rim Fire is typical of today’s wildfire problem in the western U.S.: A century of fire suppression has undone the natural cycles in which intense, tree-killing fires were small — perhaps a few hundred acres — and the large fires flashed along the ground, clearing brush and removing fuels.
In other ways it is different: It is centered on steep canyon terrain that favors fuels like grasses and chapparal, and is dryer than the region overall. And it is occurring in circumstances that seem to offer judgment not only on traditional fire-fighting policy but also on more recent management decisions.
Some of the areas burned in the Rim Fire redefine the typical notion of “old growth,” consuming “remnant islands of pine and Douglas fir trees that were 400 years old,” according to the Los Angeles Times. Scott Stephens, who teaches fire science at Berkeley, told the paper that
After the 1987 wildfires, the Forest Service also reforested some of the Stanislaus forest burn area with thousands of acres of pine plantations. Now those young tree plantations are perfect wildfire fuel.
“It’s almost like a giant shrub system, Stephens said of the plantations, adding that most have never been thinned. Although the Forest Service has approved thinning projects, it hasn’t had the money to conduct many of them.
And John Buckley, a former Forest Service firefighter who now works for an environmental group centered on forest health, told the paper that “plans to conduct controlled burns to reduce fuel levels on 7,000 acres of the Stanislaus forest have languished for years for lack of funding.
“If prescribed burning had been done in many of these areas, it would have been easier to stop (the fire) or it wouldn’t have done so much damage,” Buckley said.
Noting that the taxpayers’ tab for fighting the Rim fire is $20 million and growing, he said there was good reason “not to wait until there’s a massive fire and then throw money at it.”
Is California ready for more?
It’s anybody’s guess what the final cost of fighting the Rim fire may be. At this writing, total personnel assigned to the battle were approaching 5,000 and the blaze was judged to be about 30 percent contained.
Some 4,500 homes were considered at risk, in areas both east and west of the fire zone, and weather conditions were favorable for it to grow still larger —although, paradoxically, unfavorable for the setting of control fires at its perimeter.
Earlier in the week, after obtaining federal emergency assistance, Gov. Brown said the Rim fire “is something we have to live with — it may even get worse in years to come —but California will be ready for it.”
Let’s hope he’s right.
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(A U.S. Forest Service information page on the fire, updated frequently, is here.)