Fire Hazard ??

At present, the forest is almost like a cloud forest; it traps the moisture in the fog, so the ground is almost always damp in there. Though UCSF’s application for FEMA funding was based on the assumption of fire hazard, the evidence is overwhelming that it’s very low (for the whole story and a discussion of the evidence, see the next section.

But it’s possible to create a fire hazard.


1. The thinning of the forest will make it dryer and windier, and the scrub and weed that will substitute the ferns and blackberry will be more flammable. The felled trees will be chipped and the dry logs and chips left in the forest – increasing the fuel load.

cloud forest june 24 09 003

2. The eucalyptus is more fire-resistant than anything that will grow in its place. In the 2008, a fire burned across Angel Island, which was deforested of most of its eucalyptus twelve years ago. The grass burned – and the burn stopped at the line of remaining trees. A grass fire on Angel Island was relatively risk-free; one in the midst of housing and hospitals would be a crisis. We have more on eucalyptus and fire on our Eucalyptus Myths page.

3. In the 1930s, the forest was logged. In 1934, there was a 10-acre fire, and logging stopped. There’s been no significant fire since then. Drying out the forest could recreate the 1934 conditions.

4. There is already evidence that opening up the forest increases the fire hazard. Between 2003 and 2009, the fire risk on the mountain increased. The main difference was that this was a time when a lot of trails were being opened into the forest and drying it out.

5. UCSF will need to provide for ongoing maintenance of what will become a high-maintenance garden rather than a no-maintenance forest. Once the forest is removed, keeping the place from becoming flammable scrub will apparently be performed by goats and chemicals. It will require thousands of applications of herbicides – probably Roundup/ Garlon – for years to prevent resprouting and control weed-growth.


UCSF applied to FEMA for funds on the basis that the forest had a Very Severe Fire Hazard. It doesn’t. (At least unless UCSF and the Mount Sutro Stewards implement the thinning and drying out of the forest.)

Here’s our discussion of the fire hazard in the forest in its natural state, and the arguments that were made to FEMA, together with relevant pictures.

(Note: Many of the comments below reference that discussion and data.)


20 Responses to Fire Hazard ??

  1. Pingback: Destroying the forest to save it? « Save Sutro Forest

  2. The Garden Coach says:

    It’s not just the fire hazard that IS a problem.
    Look at the eucalyptus and ivy towers for the crashing systems they are.
    The inability for you to see this plantation for what it is, a crashing system, is absolutely perplexing. We have a major management problem here. The eucalyptus hav hangers everywhere and have killed several people in San Francisco! Wake up!
    History will not look kind on this do nothing “Save Sutro Forest” campaign.
    Moreover, why you think eucalyptus, English ivy and Himalayan blackberry are anything but neglect is a total joke. This plantation experiment and vegetation complex is a clear failure. It is highly unusable for both the average recreation user (try pruning blackberry off the trail constantly), and most wildlife that did exist here before the eucalyptus strarted infilling and shutting out all light; not to mention the views.
    Let people manage the plantation/forest.
    Thank you for considering another view!
    The Garden Coach.

  3. savesutro says:

    Garden Coach, thanks for putting your comments out here.

    Have you been into the forest? It is NOT a “crashing system” – it’s a healthy ecosystem, just not a “native” one. It’s evolved over 120 years. The wildlife are known to use the forest, while the native garden on the summit has hardly any. “Neglect” is the normal state for a natural area.

    As far as I know, no one has been killed by eucalyptus in Sutro Forest; there was one tragic incident in Stern Grove parking lot with a [ETA: Redwood] tree identified as unsafe that had not been trimmed despite requests.

    It’s sad that the forest is in the hands of those who think it’s a total joke and a failure, and despise its real beauty and value as a habitat, in addition to its position as a remnant of San Francisco’s historic 1100 acre forest.

    For bare hills, we already have Twin Peaks and Tank Hill. This forest is special.

  4. The Garden Coach says:

    I grew up in San Francisco and continue to spend more time than the average user in these parks. If you don’t consider the ivy strangling those poor eucalyptus to their tops a crashing system, you have not been to Mt. Davison either. THEY ARE FALLING ALL THE TIME! “Evolution” does not occuer in 120 years but extinction does. We have inherited a disaster that is starting to reach it’s tipping point. We have never been here before in history. Just go look at the scarily leaning trees and the ones that have fallen.
    These ivy-euc. towers are falling quickly! You must wake up and help or the blood will be on your hands! Get money to help manage the clearly hazard trees at least, not all of them, not clear-cutting etc. before more people and other trees are hurt!
    Mt. Davidson is also in desperate need of management from hazard (falling, ivy-ridden eucs. .) Any forester worth their weight that I have spoken with knows this. You must increase your research and trust that there are folks that even if they could get the money to manage the unplanned “Sutro Ecology”, could not handle all the work needed to save these forests.
    Your bias is so deep and fear-ridden. Wake up and help! Call and help the meager stewards.

    • savesutro says:

      Uh, blood on our hands, Garden Coach? You wouldn’t be exaggerating or anything?

      Hazardous trees are being removed. The city trims or fells all trees that are a danger to property, or it tries to. I saw such a process recently in Forest Knolls, and I am sure they would do the same along the streets below the Mt Davidson Forest.

      In Mt Sutro at least, the trees aren’t falling, quick or slow. This misguided project isn’t about removing hazardous trees. And yes, a planted forest can become a stable eco-system in 120 years. It’s already full of birds and animals. The blackberry and ivy provide food and cover; the trees catch the moisture, the duff holds it, and the undergrowth protects it from drying out.

      There was nothing on Mt Sutro that was driven to extinction. But chopping down the trees would destroy the eco-system that exists there now.

  5. Pingback: Help Save Mount Sutro Trails « Save Mount Sutro Forest

  6. Steve Finnegan says:

    Here are some FACTS and some opinions about the Fire Hazard Designation of Mt. Sutro.

    San Francisco County does not contain any State Responsibility Area (SRA) land, and therefore does not have an SRA FHSZ map. This means the state will not classify anything above moderate in non SRA land.

    SF County has reclassified some areas within LRA-Local Response Area as very High.

    San Francisco County’s Hazard Mitigation Plan came out after the State’s Map and classification. Here is the link the SF’s map:

    Here is significant part relating to Mt. Sutro:

    CAL FIRE has developed a fuel ranking assessment methodology that assigns ranks (moderate,high, and very high) based on expected fire behavior for unique combinations of topography and vegetative fuels under a given severe weather condition (including wind speed, humidity, and temperature). As shown on Figure C-13 (Appendix C, Figures), high and very high wildfire hazards include San Francisco’s large parks and open spaces, and Yerba Buena Island.

    The phrase :”based on expected fire behavior for unique combinations of topography and vegetative fuels under a given severe weather condition ” is very significant. Despite peoples desire to describe Mt. Sutro as a “cloud forest”, it is neither. It is small mountain with some areas with steep topography loaded with Eucalyptus trees (fuel) growing on it and many that are dead or dying.

    If the weather conditions are right, a significant fire could happen. When are these times: In 1995 during the vision fire. There were times during the summer of 2008, when the fuel would burn.

    Extent and Probability of Future Events
    The CAL FIRE Fuel Rank model shown on Figure C-13 (Appendix C, Figures) displays the
    extent (moderate, high, and very high) of wildfire hazards in San Francisco. In general, the susceptibility for high and very high wildfires dramatically increases in the late summer and early autumn as vegetation dries out, decreasing plant moisture content and increasing the ratio of dead fuel to living fuel. Common causes of wildfires include arson and negligence.

    However,as noted above, a recorded wildfire has not occurred in San Francisco. Therefore, the probabilityof a future wildfire event is unknown.

    This last sentence is inaccurate. There was a 10 acre fire on Mt. Sutro in 1945 and many other small ones There will be another one someday. Will it burn homes? Probably not, but the potential is there. I do not believe it deserves the classification as very high and do not know all the reasons the County decided to reclassify Mt. Sutro and other areas as Very high. If someone knows, I hope they will respond.

  7. webmaster says:


    The SF County report’s map puzzled us too. It gave CalFire as a source but was completely different from CalFire’s actual map. (CalFire’s map shows only one High Fire Hazard area, right on the border near San Bruno Mountain – and yes, they do have a map of the Local Responsibility Area.)

    The SF County’s map, prepared by URS, is actually dated 2005. It used a different methodology, and guessing from the other maps in the document, one based on a computerized technology.

    CalFire’s assessment is the more recent one. The map is dated 2007, and the updated assessment is dated December 2008 – the same month that San Francisco was adopting the report.

    There’s a discussion of these maps here:

    As to earlier fires: conditions in the forest in the first half of last century were quite different. The forest was more open and dryer because there had been logging after Adolf Sutro’s death. In fact, the very conditions this FEMA plan would have created. It’s the dampness of the forest that keeps us safe. Check the “Fog Log” on this website here:

    Through the summer, the mountain is always wet because of the fog drip – it actually rains in the forest! The place never gets a chance to dry out. The important thing is not to open it up and dry it out. The only place that dries out now is actually the open space of the Native Garden.

  8. Steve Finnegan says:

    Thanks for pointing out the area next to Mt. San Bruno designated by Cal Fire as High in LRA. When I spoke to them, they made the statement that they do not designate anything within LRA above Moderate. Perhaps because it borders an SRA area of San Mateo County labeled High, they made an exception.

    I must take exception to the statement that “the place never gets a chance to dry out” and “the only place that dries out is the open space of the Native Garden.”

    My definition of Dry in relation to fire hazard is: Is the fuel able to burn. The slope below the chancellor’s residence was dry in Late May of 2008 around the time when the Summit Fire in Santa Cruz burned 35 homes and 64 outbuildings. I mentioned the fire behavior on that fire in one of the community meetings. That fire burned intensely while the fog was in.

    Similiar fog conditions or lack of for close to a month occurred in San Francisco during that time. I have not checked the Fog Log to see if those days are included. The fog may have been in briefly during May and June, but not the normal June weather pattern for the City. There were some windy days during that time and the fuels were dry.

    I grew up on Ashbury Street and spent lots of foggy summer days in the City hiking in Sutro Forest as a kid. I like to hike the trails in the thick and dense eucalyptus groves of Mt. Sutro. I also like to hike on the summit in the sun with the native wildflowers in bloom and look out to the ocean. I hope to continue to hike the trails and appreciate the websites and comments.

  9. webmaster says:


    Do you think perhaps whoever you spoke to at CalFire misspoke, and meant that there was nothing above Moderate in our area? Because they do have a map of Local Responsibility Areas showing High and Very High Hazards in other places.

    We don’t have a Fog Log for May and June 2008, but it may be possible to trace it from weather records. The UCSF FEMA proposal and the Q&A talked of the dry period from Sept-Nov, and that’s the period for which we kept the log.

    The Santa Cruz fire was brush and chaparral fire. Areas of Sutro Forest that are opened up do get dry. That’s why it’s so important to not let it dry out, and why we think the proposed “fuel reduction” would actually break the mechanism that keeps the forest damp.

    If you like sunny summits with views and wildflowers, have you been to Twin Peaks? It’s amazing this year. (If you don’t mind oxalis and wild mustard.)

    I personally love the feeling of seclusion in the forest, as well as the views from Twin Peaks. I think there’s room for both in this wonderful city.

  10. webmaster says:

    Also: I’ve never been to the Chancellor’s residence, but perhaps the area below it is more open and dry because of the building? If that’s the case, then perhaps she should install a sprinkler system? I’m glad there’s irrigation up in the native garden, even if (as I am told) it’s not being watered now. It means that the driest part of the mountain can be wetted down if needed.

  11. Nature Lover says:

    A couple of observations about Steve’s posts…

    He says that Mt. Sutro is “…loaded with Eucalyptus trees (fuel) growing on it and many that are dead or dying.” Actually the forest on Mt. Sutro is very young in relation to the life of Blue Gum eucalyptus, which is between 200 and 400 years in Australia. We don’t know how long it will live in California because it hasn’t lived here that long. Experts (Doughty in The Eucalyptus) think it will live longer here because it doesn’t have as many natural predators as it does in Australia.

    However, if a few of the eucalypts on Mt. Sutro are indeed dead, there is nothing to prevent UCSF from removing the dead trees. They have already removed many that were considered hazardous by a certified arborist firm. They can do the same for dead trees if they wish. That doesn’t justify the wholesale destruction of most of the forest as they originally proposed.

    Steve also says, “My definition of Dry in relation to fire hazard is: Is the fuel able to burn.” That may be Steve’s personal definition of “dry,” but such an all-or-nothing definition isn’t consistent with fire science. Fire science uses a full range pf conditions from wet, through moist, through dry, to finally dead. And the degree of moisture of fuel is directly correlated with how easily the fuel will ignite. Fire science says that ignition is less likely on a foggy day when fuel is moist. That’s not to say that ignition is impossible, but rather that it is less likely in a moist environment.

    And so it follows, that although fire on Mt. Sutro isn’t impossible, it isn’t likely. It is therefore inappropriate to use FEMA funds that are designated for fire hazard mitigation because FEMA funds are limited and should be used where they are needed most. They are not appropriately used to improve the view from Mt. Sutro.

  12. webmaster says:

    Nature Lover is right, there really aren’t many dead trees and UCSF can remove them. But I’d also suggest that they shouldn’t be removed unless they are directly hazardous. They’re important as habitat and part of the ecosystem… there’s a good discussion of that on the Muir Woods website, which we referred to here:

  13. Nature Lover says:

    Yes, dead trees are useful to wildlife. No question about that. However, if fire hazard mitigation is your highest priority–which UCSF continues to claim–then removing the most flammable fuel is more important than providing habitat for animals.

    As always, it is strictly a matter of opinion what is most important. However, in this case UCSF has claimed that they are concerned about fire hazards. They could easily put their money where their mouth is, if–in fact–that is their highest priority.

    There are, of course, many other things that UCSF could do to lower fire hazards, such as focusing their effort around Aldea housing. They could create the defensible space around Aldea housing that is considered the starting point for any fire hazard mitigation. The fact that their plans don’t even mention such basic actions is one of many indications that fire hazard mitigation was never the goal of this project. It was merely an attempt to fund their project from an available fund source which required such justification.

    So, Steve, if you are sincerely concerned about a fire on Mt. Sutro, why not advocate for creating defensible space around Aldea housing or screening the vents in the eaves so that embers cannot enter the attic? Unfortunately that won’t improve your view from Mt. Sutro.

  14. Steve Finnegan says:

    “So, Steve, if you are sincerely concerned about a fire on Mt. Sutro, why not advocate for creating defensible space around Aldea housing or screening the vents in the eaves so that embers cannot enter the attic? Unfortunately that won’t improve your view from Mt. Sutro”

    Thanks for reading my mind. I would be happy if UC stepped up and cleared the dead leaves off the roofs of all the buildings in Sutro. I really am not that concerned about a fire on mt. Sutro. I have mentioned several times about the potential not the probablility.

    As far as the view, that is nice to call it mine. I wish I had that view from my window. It was the view from Sutro many years ago. For now, I will continue to enjoy the view from there and twin peaks as our webmaster mentions is very nice this time of year. Thanks

    Nature lover makes many good points. I will revisit my all or nothing definition of dry. I agree as well that there are many areas where FEMA money could be used more wisely. I thought Ray Moritz makes some good points which I put below.

    “Ray Moritz, who we have met before as a forester, introduced himself as a Fire Ecologist. He said that fire danger was related to three things: The fuels; the topography; and the weather. He noted that the fire danger was mild, because though the terrain was steep, there was a low amount of fuel on the ground and the trees were so tall that the canopy was unlikely to catch from a ground fire. Most importantly, in San Francisco, the window of opportunity for a fire was very small; there were only a few days annually when the forest was dry. He also said cigarettes (which people had feared as an ignition source) are actually not a danger. [ETA: He made 16 practical experiments with oven-dried eucalyptus leaves and cigarettes; he did not achieve ignition even once.] The greatest danger, he suggested was when people did not clear debris from the roof area around fireplace chimneys. However, he pointed out that the fire station was nearby, with a response time of under two minutes, and a fire hydrant sat opposite the proposed trailhead.”

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