Why did Marin Municipal Water District stop using herbicides?

The Marin Municipal Water District stopped using herbicides on its properties in about 2005, in response to the public’s concerns.  MMWD then hired consultants to evaluate the risks of using herbicides.  As a result of those studies, MWWD decided in 2015 to make a permanent commitment to NOT using herbicides on its properties.

A member of the Board of Directors of MMWD has written a public comment for the East Bay Municipal Utilities District Master Plan in which he explains why MMWD made this decision.  His letter is available here:  MMWD – public comment from Board member

Here is a summary of the reasons why MMWD no longer uses herbicides on its properties:

  • The International Agency for Research on Cancer reclassified glyphosate as a “probable carcinogen.”
  • The California Office of Environmental Health Hazard Assessment has recommended that glyphosate be listed under Proposition 65.
  • A study conducted by researchers at UC Davis found that glyphosate persisted for at least 84 days when applied to foliage. “The clear inference from this study is that glyphosate could well migrate to water courses and streams which feed MMWD’s reservoirs.”
  • The toxicity of herbicides to aquatic life and habitat is well documented.
  • The persistent toxicity of many herbicides decreases soil biota which reduces CO2 absorption. “Hence, it appears that the non-pesticide approach may well assist with society’s ongoing efforts to remediate GHG through regenerative forestry practices.”


Thank you, MMWD, for writing this letter to EBMUD about their use of pesticides on our watershed in the East Bay.  EBMUD should follow your lead!

Please write your own public comment on the East Bay Municipal Utilities District Master Plan.  Public comments are due by Friday, September 16, 2016.  Comments should be sent to watershedmasterplan@ebmud.com or by mail to Doug Wallace, EBMUD, 375 11th St, Oakland, CA 94607.

There is also a petition to EBMUD that we encourage you to sign:  

Sign the petition!
Sign the petition!

Concern about herbicide use: Legitimate or “chemophobia”?

Recently there was a brief dialogue about herbicide use in San Francisco’s so-called “natural areas” in Jake Sigg’s Nature News that was of some interest to those who consider such use a contradiction in a public park designated as a “natural area”:

  •  Jake Sigg:  “Spurious, damaging information being circulated regarding herbicide use in our open spaces:  Mischievous people…are circulating false information…whipping up fears that have no foundation”  (Nature News, February 14, 2011)
  • Reader:  “…Garlon is legally classified as a hazardous chemical.  I am therefore writing to supply you with information from reputable sources.  I ask that in your future communications on this subject, you accurately describe the facts that are known about this chemical.” (Nature News, February 18, 2011)
  • Jake Sigg:  “The chemophobia rampant in this country is primarily based on emotion and anxiety, and does us a great disservice.” (Nature News, February 18, 2011)
  • Jake Sigg:  “The anti-herbicide crazies quickly seize on articles like this NYT one as proof of their contentions…” (Nature News, March 30, 2011)

This dialogue and the positive feedback that Mr. Sigg reported from his readers in support of herbicide use, suggest that herbicides are an important tool for the native plant movement.  They are anxious not to lose this tool in their crusade to eradicate non-native plants and trees.  After researching how much herbicide is being used by the Natural Areas Program, we can understand why they angrily defend its use. 

Herbicide use by San Francisco’s Natural Areas Program

The Natural Areas Program (NAP) reports having used herbicides 69 times in 2010:  36 applications of Garlon, 31 applications of Roundup, and 2 applications of Milestone.  Putting those numbers into perspective, other areas (those not designated as “natural areas”) in the Recreation and Park Department sprayed Garlon, the most hazardous chemical, only a few times in 2010.

 About 20% of these herbicide applications were done by a contractor who was paid $9,000 per application.  The employees of this contractor are therefore equally committed to this source of revenue, contributing to the economic interest that is a motivating factor in the native plant movement.

Not all of the “targets” of these sprayings are identified, but those that are include:  oxalis, blackberry, ivy, fennel, cotoneaster, hemlock, pampas grass, broom, erharta grass, mustard, and thistle.  Blackberry is an important source of food for wildlife in the city. We hope that children in the park do not graze on the blackberries.  Garlon was also sprayed on Scabiosa, which has not been identified as an “invasive plant” by the California Invasive Plant Council.

Glen Canyon, with a creek running through it and a year-around day care center adjacent to that creek, was sprayed 12 times.  Twin Peaks, the watershed to that creek, was sprayed 16 times.  Lake Merced was sprayed 3 times, despite the fact that it has been officially designated as red-legged frog habitat.

What is known about these chemicals?

The City’s policy regarding “Integrated Pest Management” classifies the chemicals used on city properties in terms of the risks associated with their use.  Here is how the City’s policy classifies these chemicals: 

  • Garlon:  Tier I, Most Hazardous.  Use Limitations:  “Use only for targeted treatments of high profile or highly invasive exotics via dabbing or injections.  May use for targeted spraying only when dabbing or injection are not feasible and only with use of a respirator.  HIGH PRIORITY TO FIND ALTERNATIVE.” 
  • Roundup:  Tier II, More Hazardous.  Use Limitations:  “Spot application of areas inaccessible or too dangerous for hand methods, right of ways, utility access, or fire prevention.  Use for cracks in hardscape, decomposed granite and edging only as last resort.  OK for renovations but must put in place weed prevention measures.  Note prohibition on use within buffer zone 60 feet around water bodies in red-legged frog habitat.”
  • Milestone:  Tier I, Most Hazardous

    Spraying Garlon on Twin Peaks without use of the respirator required by City policy, February 2011

Federal law also requires that chemicals be evaluated by the Environmental Protection Agency (EPA) before being commercially available to consumers.  The EPA conducts a number of tests of toxicity, reports the results of those tests on a mandated Material Safety Data Sheet (MSDS), and classifies the chemical with respect to its relative toxicity.  Here are a few highlights from the MSDS for these chemicals:

  • Garlon 4 Ultra is defined as a “Hazardous Chemical” according to the OSHA Hazard Communication Standard.  “Material is highly toxic to aquatic species” and “slightly toxic to birds.”
  •  Roundup Pro is defined as a “Hazardous Chemical” according to the OSHA Hazard Communication Standard. Toxicological effects in rats:  “decrease in body weight gain; histopathologic effects.”  “Moderately toxic” to aquatic life.

The Marin Municipal Water District (MMWD) quit using all herbicides in 2005 in response to the public’s protests.  They have been engaged in a process of evaluating herbicides for possible use in the future.  In 2008, MMWD contracted for a risk assessment of 5 herbicides they were considering for possible use.  That risk assessment determined that Garlon 4 Ultra is the most hazardous of the 5 chemicals that were evaluated.    MMWD is not considering the use of Garlon in the future. 

Does NAP’s herbicide use conform to the City’s Integrated Pest Management Law?

 San Francisco’s Integrated Pest Management Ordinance makes the following commitments regarding pesticide use on the city’s properties: 

  • 300a “…the policy of the City..to eliminate or reduce pesticide applications on City property to the maximum extent possible.”
  • “The City…shall assume pesticides are potentially hazardous to human and environmental health.”
  • “The City shall give preference to reasonably available nonpesticide alternatives when considering the use of pesticides.”
  • “Consider the use of chemicals only as a last resort.”
  • “This Chapter applies the Precautionary Principle to the selection of reduced risk pesticides and other pest management techniques.”

The City’s ordinance that obligates the City to follow the Precautionary Principle makes this commitment: 

“A central element of the precautionary approach is the careful assessment of available alternatives using the best available science. An alternatives assessment examines a broad range of options in order to present the public with the consequences of each approach. The process takes short-term versus long-term effects or costs into consideration, and evaluates and compares the adverse or potentially adverse effects of each option, giving preference to those options with fewer potential hazards. This process allows fundamental questions to be asked: ‘Is this potentially hazardous activity necessary?’ ‘What less hazardous options are available?’ and ‘How little damage is possible?’”

We do not believe that herbicide use by the Natural Areas Programs meets the standards of either the City’s ordinance about pesticide use or its commitment to the Precautionary PrincipalThese laws are theoretically rigorous, but the enforcement of those laws is not.  The Natural Areas Program is using an herbicide (Garlon) categorized by City policy as the “Most Hazardous” most of the time.  They are using that chemical in sensitive areas in which water can be contaminated and in which children can be exposed.  Their use of that hazardous chemical has increased over time and they have been using that chemical for at least 5 years, perhaps longer (the 2006 management plan for the Natural Areas Program reports the use of this chemical).  If Garlon has not been capable of eradicating in 5 years, the non-native plants that are the target of the Natural Areas Program, it is not likely to do so in the foreseeable future.  

Legitimate concern or “chemophobia”?

Let the reader be the judge.  Given what we know about these chemicals, the frequency of their use, the length of that use, and the locations of that use:

  • Do you think there is reason to be concerned about the herbicides that are being sprayed on our public parks? 
  • Do you think that places that have been designated as “natural areas” should be sprayed with herbicides which are legally and officially designated as hazardous chemicals? 

Herbicide Subterfuge

The public is unaware of the scale of herbicide use in our parks and public lands.  Nor are they aware of the toxicity of herbicides to humans and animals.  We will describe just two examples of the subterfuge that is used by “restorationists” to hide the use of herbicides.

The management plan of San Francisco’s Natural Areas Program (NAP) includes a description of the NAP’s herbicide use. Table 4-2 of the plan identifies 16 species of non-native plants and trees on which herbicides (Roundup and Garlon) are used.  Although the plan states specifically that herbicides are used, the Initial Study of environmental impact of the program says absolutely nothing about the use of herbicides. It does not acknowledge that herbicides are used or analyze their impact on the environment and its inhabitants.

Twin Peaks, San Francisco

The use of herbicides by a program calling itself the “Natural Areas Program” is particularly ironic in San Francisco, a city that has officially adopted the Precautionary Principle.  The PP theoretically obligates the city of San Francisco to ban any substance that might harm the environment or its inhabitants, even if there is not yet scientific evidence of that harm.  In the case of herbicides, there is plenty of evidence of the harmful effects on humans and other animals.

The East Bay Regional Park District is also using herbicides without acknowledging the risks in doing so.  In its Wildfire Plan, EBRPD misinforms the public that the Marin Municipal Water District is using herbicides:  “Using herbicides to control invasive [AKA non-native] plant species…can be an efficient and cost-effective method…Recent studies conducted by the Marin Municipal Water District (MMWD)  confirm this approach; the results of their studies on the use of non-chemical control methods for the control of invasive non-native plants indicated that non-chemical alternatives are ineffective for large-scale vegetation management projects. (see Appendix H…)”  (page 92) .  In other words, EBRPD in its Wildfire Plan is inaccurately claiming that MMWD is using herbicides when they are not.  MMWD has confirmed in writing that they have not used herbicides since 2005.

But, EBRPD doesn’t stop there.  When the public pointed out to EBRPD during the public comment period on the Environmental Impact Review (EIR) that MMWD is not using herbicides, EBRPD responded (Response to Comments) as follows:  “As of March 2010, MMWD’s draft reports and analyses have shown no significant risk associated with the use of the chemicals studied on human health, animals or non-target plants, and a greatly increased average annual cost for eradicating 100 acres of the 750 acres of broom without the use of herbicides…”  (page 394) Whoever wrote that sentence has either not read MMWD’s risk assessment of herbicide use or is misrepresenting it.  In fact, MMWD’s risk assessment is perfectly clear in describing significant harm to the environment caused by herbicide use.

No wonder the public is in the dark about the use of herbicides.  Every effort is being made to keep them in the dark.