We support the San Lorenzo Valley Water District Plan to control Silver Wattle Acacia, French Broom, and Portuguese Broom at the Olympia Wellfield site. We are environmental scientists, each with over 20 years of experience restoring coastal California ecosystems. We consider the proposed methods consistent with best management practices to remove these invasive species, conserve the threatened Santa Cruz sand hills habitat, and minimize risks to water quality.

The Santa Cruz sandhills are a unique plant community restricted to the Zayante sand soils of the Santa Cruz mountains. They host several rare species of plants and animals that only live in this open sandy habitat, including the Mount Hermon June Beetle and Zayante Band-Winged Grasshopper which are protected by the federal endangered species act. The sandhills are threatened by invasive woody species, such as broom and acacia, but removing them is a challenge that requires a carefully crafted, tiered approach. Neither of us advocates herbicides as a first choice. Rather we, like most land managers, support an integrated weed management approach that includes thoughtful consideration of a range of methods to maximize efficacy while minimizing risks to non-target organisms, soil and water quality, worker safety, and the health and safety of watershed residents. In some cases, including the limited use of herbicides allows these multiple goals to be achieved.

The SLVWD plan provides a well-justified and complementary mix of approaches that recognizes the constraints of the ecosystem and the challenge of these noxious weeds. Small invasive plants will be removed by manual methods to minimize herbicide use. Large plants will be controlled by cutting and painting glyphosate directly on the stems. A Qualified Pesticide Applicator License and Personal Protective Equipment is required for these workers. This method is used by land managers throughout California to successfully control broom and acacia while minimizing herbicide use. It is mandatory to apply some herbicide after cutting these species to prevent resprouting. Painting (not spraying) a 50% concentration of the herbicide on the stems means that a minimal amount is used and avoids contact with non-target organisms. Glyphosate will not be applied if rain is forecast, so there is plenty of time for the herbicide to be absorbed by the target plants.

Some people opposed to the project have suggested that the 19,000 large stems could be removed manually. Manual removal would be extremely challenging, given the size of some of the plants, and would cause extensive soil disturbance. This is prohibited by the US Fish and Wildlife Service, since Mount Herman June Beetle larvae, which live a few inches underground, could be killed. Manual removal of large plants may also increase soil erosion and disturb the native seed bank.

Concerns have been raised about glyphosate, since it was recently listed as a ‘probable carcinogen’ by the State of California. The risk from chemicals, however, is determined by both concentration and extent of exposure. The studies cited for this listing were based on exposure to workers who apply the herbicide routinely, not bystanders or people who live in the watershed. We are all exposed to carcinogens regularly, such as soot, solar radiation, and very hot beverages (www.cancer.org/cancer/cancer-causes/general-info/known-and-probable-human-carcinogens.html). We don’t, however, stay indoors all the time to avoid sunlight; we use sunscreen and hats to limit our exposure. Similarly, by applying a small amount of glyphosate directly to the stems, with proper protective gear, the SLVWD plan minimizes risk to people and non-target plants and animals.

We applaud the professional approach the District is taking in land stewardship. If we chose to never use herbicides in the sandhills, then the broom and acacia will spread, and the open, sandy habitat for those rare and endangered species will be lost. Extinction may follow.

Karen Holl is a Professor of Environmental Studies at the University of California, Santa Cruz who conducts research on and teaches about restoring coastal California ecosystems. Bryan Largay is Conservation Director for the Land Trust of Santa Cruz County, and previously worked for the Elkhorn Slough Reserve and the Resource Conservation District.

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(9) comments

george mcmenamin

Several things:
There are a number of types of Roundup besides the original, including Roundup Custom for Aquatic Habitat (it used to be called Aquamaster). It is 53.8% glyphosate and the rest is water. It is the same chemical composition as Rodeo.
It has no surfactant added.
The Cut and paint method usually does not need any surfactant or foaming agent, as you are applying the herbicide quickly (within 1 minute or so) directly into the vascular system of the plant.
By using Rodeo or Roundup Custom for Aquatic Habitat with the proper timing and concentration, there is no need for any surfactant when using the Cut and Paint method

george mcmenamin

I am an environmental consultant with over 1600 hours pulling French Broom in 3 counties and all types of soils. I have tracked the depletion of the seed bank at several sites for 10+ years. I also have 30-40 hours pulling it at this particular site. I train crews on hand pulling techniques for French broom (there are some tricks beyond a weedwrench) and it is definitely not faster, as an initial control. However, I do not see the speed of the methods used as a critical element, unless the work is delayed too long, in which case none of the methods will work efficiently.
It does have the advantage of increasing the rate of depletion of the seed bank. However, that would need to be weighed against the damage to endangered species present and the soil itself. I find that protecting endangered species should carry significant weight when methods are discussed. I use herbicide, as a last choice, and have ran experiments on concentrations, types of surfactants and eliminating surfactants, but sometimes it is the only truly logical option.
In this case, I absolutely agree with Karen Holl and the general content of her article. Herbicide use to some level is going to be necessary to reach the critical goals for this highly endangered habitat and the species located within it. There is potential for a professional discussion with regard to the timing, concentration, application tools and locations for herbicide use for this project, but the careful limited use of herbicide for at least some of the proposed area is the only practical choice to achieve all of the critical goals.Oversight of the herbicide applicator and their activity, by a neutral, knowledgeable observer, should result in limiting the amount of herbicide used to the greatest degree and prevent any collateral damage.
With regard to Flaming, the technique should be used in wet weather and requires specific training (see Ken Moore video). Flaming requires practice and skill.

Karen Holl

A few quick reply to specific queries about our opinion piece.

1. The species of broom and acacia that are present on the site nearly always resprout if cut without applying herbicide. So cutting them without some direct herbicide application is ineffective to control the species.

2. The torching method only works for very small plants. A propane torch is held above a seedling which results in the water in the leaves boiling and in turn ruptures the cells. This methods is not effective for larger plants.

3. I do conduct research on non-chemical methods for invasive control and as noted, non-chemical methods are preferable. But, they are typically more expensive and often not as effective which is why a judicious selection of approaches tailored to site conditions, extent of the invasion, and size of the plants is needed.

4. Bryan Largay and I have no connections with the Board of Directors.

Bill Smallman

Often, people pull the plants and seeds get spread everywhere, so that's when you see a lot of sprouts, which can either be pulled or burned. If the area is basically sand, and the native plants are gone from the French Broom, torching may be the easiest method. Cutting and spraying with Round Up is still about the same amount of work as pulling, you still have to drag numerous large plant into a burn pile, carrying a weed eater with a blade an plants falling on you + other guys grabbing the plants. Personally, I work faster pulling them out if the soil is not hard clay, so bottomline your argument is false that it will cost more. Agreed, plants must be pulled 100%, likely to be deeper than 6 inches, easy to do in sandy soil. US Dept. of Fish and Game needs to be criticized and negotiated with their harmful policies of using toxic chemical. Do I smell a lobbyist from Monsanto? Don't need to do any research, the far more informative research was done by tens of thousands of people over the years who been eradicating this plant as long a I can remember. know what to do, and we didn't need or use Round up.

Tao Orion

I'm curious about your claim that applying herbicide to cut stumps is "mandatory" to prevent resprouting. Who's mandating this practice? Also, I noted in the management plan that propane torches are used to control small (less than 20 cm) plants, but that there are few (at this point) on the site. Are you aware of any studies on the use of propane torches on resprouting broom? It seems like a similar, but more protracted approach to achieving the same goal (and one that doesn't use herbicide).
And, although you state that the "probable" carcinogenicity studies on glyphosate are mostly from farmworkers with high occupational exposure, this doesn't mean that glyphosate is safe. There are other studies that have not been incorporated as part of the EPA pesticide registration process (completed in 1974 and not updated since then). These studies show glyphosate's significant impacts on soil mineralization, soil microbiology, and effects on animal immunity because of its disruption of the shikimate pathway (used by all bacteria, even those in our own bodies). And, Round-Up isn't just glyphosate. The so-called "inert" ingredients that make up Round-Up PRO (one of the herbicides to be used in the plan) make up 49.8% of the formulation. The exact ingredients are unknown and are not part of the minimal toxicity tests undertaken by the EPA as part of the pesticide registration process. Studies on some commonly used "inert" ingredients (found in Round-Up) include the surfactant POEA, which has been shown to induce apoptosis and necrosis in human embryonic, placental, and umbilical cells - https://www.ncbi.nlm.nih.gov/pubmed/19105591. The breakdown products of glyphosate and POEA have also been shown to be long-lasting in soils, and have never been analyzed for toxicity...or potential mobility into water sources such as the one this plan hopes to "protect" by applying herbicide.
In addition, the plan calls for the use of Triclopyr 4e, which has been shown to be mildly toxic to mycorhizzal fungi - an important part of the soil food web of many ecosystems. Given that the site is host to two federally listed endangered species with close associations to the soil - the June Bug lives out most of its larval stage underground - these potential effects on the insects themselves and their food sources should also be considered when assessing the "safety" of any herbicide.
And finally, pesticide toxicity tests only look at the effects of the so-called active ingredient - like glyphosate or triclopyr - alone. Studies looking at the potential synergistic effects of herbicide mixtures have yet to be undertaken, and the fact that restoration planners and other herbicide users routinely mix together various herbicide formulations according to their ideas of what will work, rather than using a research-based understanding of how these ingredients act together, and any potential effects they may have on the environment, sensitive species, etc., is irresponsible to say the least.
There are ways that this project can be accomplished without the use of herbicides. It will likely take longer, and the labor costs may be higher, but these non-chemical approaches are the very ones that restoration professionals should be pioneering given the weak state of pesticide registration and toxicity testing in the US and the concerning research findings of herbicide and "inert" ingredient toxicity.

Ben Lomond Rate payer

Bill, my first thought about the two comments from the so called "environmentalists" was "how are they connected to any of the BOD members. I am beginning to understand how the citizens of Flint feel. Most of this current BOD is untrustworthy and far too connected to the old BOD. I'm sick to death of hearing about the Brown act when it's in their favor. It's all so sad to have people screaming at each other - we all want the same thing. Clean safe drinking water at a fair price. We don't want to cover the butts of previous directors or build a "palace". I won't get over it no matter what the current district manager says.

Bill Smallman

Not sure who you are referring to, but I don't think there is anything nefarious going on with the Board on this issue. I think most of the Board sincerely believes spraying Round up is the best solution, as do the authors of this article. I strongly disagree, and the problem of this, what I would call, "overzealous environmentalism" is very pervasive everywhere you go. I've been involved with many construction projects where the regulations increased the cost, and found that they were not helpful towards the health of environment at all. The cost of their idea, is the unknown effects of spraying this chemical.

Karen Holl

A quick clarification that Scotch broom (Cytisus scoparius) and French broom (Genista monspessulana) are two different species. French broom and Portuguese broom (Cytisus striatus) are present on the site being discussed.

Bill Smallman

If there was any indication, or study, that showed that these bugs would go extinct from people pulling French Broom plants, we’d probably take these seemingly experts for their word and accept their advice to use Round Up. But the fact of the matter is that we need to boycott these products, and put the companies that develop them out of business. It’s a much better choice to work with nature, rather than invest into some wonder drug to try and control it. We used to call it Scotch broom, and I was very happy when it was discovered to be French, because I have a lot of Scottish blood, and have been pulling these plants all my life. Nature is much more resilient, than sensitive, but that seems to escape the thoughts of these so-called experts. The best environmentalists think holistically, and weigh all the options, not get emotional upset about a small percentage of bugs dying to the extent of choosing a worse solution. They have zero tolerance for any death of any species. Perhaps hundreds of these bugs perish, but thousands come back to take their place. It makes much more sense to do 100% manual pulling, and take measure to control erosion, planting of native plants, and go back periodically to pull or burn the little sprouts. No, they, or anyone else does not know exactly the effects of spraying this chemical, but it is clearly not worth using, ever. Learn to live with nature, and don’t be fooled all these products and GMO technology is helpful, in fact the people that use them are parasites to the earth and potentially create more problems than the ones they are trying to solve. I also urge people to find out more about what the Land Trust is involved with. You might be surprised and either stop, or not consider, donating to them.

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