California Wildfire Threatens Yosemite and Sends San Francisco Into a State of Emergency

The Northern California wildfire known as the Rim Fire is huge - and only 7% contained as of August 25th. Image of the California Fire Map by Decoded Science

The Northern California wildfire known as the Rim Fire is huge – and only 7% contained as of August 25th. Image of the California Fire Map by Decoded Science

Last week’s Rim Fire began in the remote Stanislaus National Forest, but its force and size is moving it into more populated and notable areas, including Yosemite National Park.

On the weekend, the Northern California fire was 150 miles outside San Francisco, posing a potential threat to the city’s power and water supply. Due to the concerns about the city’s utilities, city officials declared a state of emergency and continue to monitor the water quality in the Hetch Hetchy watershed, which supplies 85 percent of San Francisco’s water supply. The water from the reservoir also powers two hydro-electric generators that supply electricity to San Francisco, including the San Francisco General Hospital.

Northern California Fire: Forest is Dry Fuel Source

As of Sunday, August 25th, nearly 3000 firefighters were working to quell the blaze, which was burning in very challenging terrain. The oak and pine ecosystem has seen very little rain this year, so the forest makes an ideal dry fuel source. The fire is burning with enough force to create its own internal weather patterns, which makes it hard to predict which way it will move. As of this morning, the fire has consumed over 130,000 acres of forest and is only 7% contained, according to the US Active Fire Mapping Program.

Rim Wildfire Threatens Giant Sequoias

In addition to the over 5000 structures that are threatened by the wildfire, the Rim fire also threatens certain iconic areas of Yosemite National Park. The park is known for its groves of giant trees, the famous giant sequoias (Sequoiadendron giganteum).

The most famous grove of sequoias is the Mariposa grove, and it is the most easily accessible. The Tuolumne and Merced groves in Yosemite are the closest giant sequoia groves to the wildfire.

The Rim Fire threatens the sequoia in the Merced grove. Image by Schick

The Rim Fire threatens the sequoia in the Merced grove. Image by Schick

The Tuolumne is home to 25 giant trees, including one sequoia with a tunnel through it. The tunnel was cut in the 1870s to attract tourists to the area.

The Merced grove contains 20 giant trees. Over the weekend, park officials have been clearing brush from around the trees and setting sprinklers to discourage the wildfire from spreading to the trees, should it reach the area.

Ecologically, fire does have a role in the sequoia ecosystem, since it helps moves nutrients from the trees into the soil and helps create new soil conditions where seeds can grow. Fire opens up gaps in the forest canopy, allowing light to move into the system. While fire brings devastation, it can also bring new life. However, it takes many thousands of years to grow a giant sequoia, so the burning of these giants would mean that Yosemite would lose its most illustrious residents for many, many generations.

Rim Fire in Northern California

The Rim fire is large, and presents challenging conditions to firefighters. This wildfire also has internal variability and momentum, so it’s difficult to tell whether the trees of Yosemite and the structures within the blaze will make it through this fire season unscathed.


Active Fire Mapping Program. Current Large Incidents. (2013). Accessed August 25, 2013.

Kilgore, Bruce M. Fire’s Role in a Sequoia Forest. Accessed August 25, 2013.

NBC News. Harsh, Dry Winds Hamper Moves to Douse Massive California Wildfire. (2013). Accessed August 25, 2013.

USA Today. High Winds Likely To Push Flames Further Into Yosemite. (2013). Accessed August 25, 2013.

Google. California Fire Map. (2013). Accessed August 25, 2013.

© Copyright 2013 Tricia Edgar, All rights Reserved. Written For: Decoded Science
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  1. Jeff says

    History Evelyn! When I was a small child the Indians would come to Camas count Idaho to pick camas. I would go out and help them pick the camas. They would start fires every spring to burn off the undergrowth. The residents would complain about the burning and the Indians in general. The Interior Department came up with a policy of zero tolerance to forest fires and everybody would go up and put out the fires in the mountains. These burns kept the vegetation way down. Eventually they forced the Indians on the Reservations. No more burns meant the dead debris to accumulate. Then it was small fires that burned themselves out, now it’s major fire that move fast and destroy everything in there paths including the trees. Vegetation control is what is called is more sensible than this stupidity.

  2. Jim Snow says

    Is the global climate out of control here.? We have big major lakes and rivers drying up here in Texas… no news on that.released in the media………..

  3. Billybob207 says

    It is not convenient for us and I am distressed for one of my favorite areas of the US…but fire is natural and needed. It is just part of a cycle. Having a fabulous city in the way is another example of our hubris. Someday we’ll realize that we were not put here to “manage” nature.

    An analogy would be the coastal towns that expect to protect themselves from rising tides…so they keep rebuilding. Sooner or later the water wins.

    All that being said, my heart and hopes are with the folks facing this.

    • qmacker says

      These are not “natural” fires. All things being equal a forest fire will do good and will clear out brush and undergrowth – with very little loss of big trees. However, because we have suppressed fires for so long, we now have the following: 1) monster “crown” fires taking out and engulfing the big trees creating enormous “firestorms” that even create their own weather. This is a direct result of allowing all this underbrush to grow and not be cleared by natural fire in the normal course of events. The truth is further obscured by the “fire is good” crowd because 2) originally well-intentioned groups such as the Sierra Club have opposed any management of the (already unnatural human-induced state) forests and oppose the clearing out of the brush that we created through suppression in the first place. Get it out of your head for once and for all that these fires are natural. They are NOT natural. Massive crown fires like this are not normal and they are very damaging to all living things. If we can get our forests back to something resembling a natural state, then a natural fire is a good thing.

  4. mickeymonopoly says

    Wow. I hope they can get a handle on it and save the sequoias. It would be a tragic catastrophe to see them destroyed. I have great memories of Yosemite. It’s one of the most beautiful places on earth.

  5. Jeff says

    More than a billion dollars spent fighting fires in the west this year. The money could have been spent to clean these forests up. The policies of the Department of Interior has done a sorry job with the policies that brought things to this in the last 50 years.

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