Wednesday, March 13, 2013

Wednesday Search Challenge (3/13/13): How much death at the roadside?

Last week I was driving down a scenic California highway with my friend Pat who asked a great question:  “Why is there always a brown stripe of dead or missing grass at the edge of the highway?”  He's right--take a look. 

As we drove out of the Sierras and into the Central Valley we saw mile-after-mile of either brown grass, dead grass, or a zone of no-grass at all along the edge of the road.  It’s the kind of thing that you don’t even notice until someone points it out to you.  There’s a constant zone of death at the highway’s edge. 

To add to the mystery, when we turned onto a side road, we noticed that the grass came right up to (and in cases into!) the edge of the road.  Take a look at a roadside near where the above images were taken... the grass grows right up to the edge of the road.  

So while we’d been talking about the possible toxic effects of asphalt on grass and weed growth, this pretty clearly wasn’t the case.  There’s nothing about tar or asphalt that kills the grass.

A few minutes later, we saw the killers:  there was a truck driving slowly down the road with a man dressed in a white jump suit, clearly spraying weed killer at the edge of the road. 

When we got back onto the main road, the brown, dead zone picked up again and Pat asked today’s research question: 

1.   Just how many pounds of herbicide are sprayed along California roads each year?
 2.  And, of course, just how toxic is this herbicide?  (Should I be worried as I drive up and down these roads?  Should I be worried if I ride my bike along these sprayed roads?) 

To tell you the truth, I haven’t yet answered this question myself, so I don’t know ahead of time how easy (or difficult) this will be. 

To make things clear—let’s try to discover how much herbicide is used on California state roads. 

As usual, it’s an open Internet. Let’s dive in and see what we can find. As you discover things, post what you find to the comments stream below, and we'll collectively figure this one out.  

I usually hold back the comments until later in the day, but since this question could take some time to figure out, I’m going to let the comments become visible fairly quickly in the hope that we’ll be able to help each other out.  

Please let us know what your thought process is as you search for the answer.

And, as always, let us know how long it’s taken you to find an answer. 

Search on! 


  1. No answer yet.

    I started with a search for [ california state road authority ] to find that their department of transportation is referred to as Caltrans.

    On their web site I used their search box to search spraying and found reference to few different chemicals etc.

    Decide to go back to Google and searched [ caltrans roadside spraying ] The results are a mix of protests and information so now I need to work on filtering.

    Searching on...

  2. Sorry, forgot this again. The above took about 10 minutes.

  3. I searched:
    california department of transportation herbacide site:gov - Google Search

    I came across this document:

    From the abstract: The implementation of the IHAS technology will allow the California Department of Transportation to reduce the amount of resources required to maintain an effective weed control program using herbicides while at the same time reducing the amount of chemicals unnecessarily released into the environment.

    I haven't read through the document, but it should mention the chemicals released into the environment.


    "The research reported here was initiated at the request of the North Coast Regional Water
    Quality Control Board in response to citizen inquiries about the potential endocrine disruption
    capabilities of herbicides used by Caltrans in their roadside maintenance program."

    "As xenoestrogens, Surflan TM and oryzalin have the potential to adversely affect those biological
    processes controlled by endogenous estrogen." (p 36)

    "A relatively brief (21 d) exposure of mature, reproductively-active medaka to Surflan™ and
    oryzalin impaired fertilization of both males and females, and affected the hatching time of eggs." (p 72)

    "We have demonstrated that the xenoestrogens Surflan TM and oryzalin have significant effects on the gonads and liver." (p 115)


    [herbicide california road gallons]

    1. Interesting... except this is from 1999. Can you find something that's a bit more recent?

  6. Living in the UK I have no idea of how US state government and departments are organised but I decided to jump in at the deep end and include in the search. I also included a numeric range 2009..2013 not knowing how up to date the statistics would be. My search strategy was: roadside herbicide use pounds 2009..2013

    Top of the list was what looked like an unpromising PDF "Caltrans Stormwater Management Program Annual Report" at but the summary in the results suggested it was relevant.

    It wasn't immediately obvious from the bookmarks that the report covered herbicide use so I used Ctrl F to look for herbicide within the document. There is a section on herbicide use under Maintenance.

    On page 36 it says "Approximately 207,000 pounds of active ingredient were used to treat an estimated 57,727 acres in Caltrans’ Integrated Vegetation Management program during the fiscal year 2010-2011". I have only looked at this section out of context so I need to go back and review the whole document to make sure it is saying what I think it is.

    Taken about 7-8 mins in all so far.

  7. Here's the 1999 fundamental study from CAT (Californians for
    Alternatives to Toxics) in the first pages there's a box with the previuos volumes of herbicides sprayed by Caltrans

    Their work and brought Caltrans to a herbicide reducing plan, as is stated here:


    "Vigorous campaigns by a number environmental groups, however, have ushered in an age when the use of herbicides is under scrutiny. The non-profit environmental group Californians for Alternatives to Toxics (CATs), based in Arcata, has worked on issues involving the use of pesticides -- including their use in forestry, vitriculture, roadside maintenance, and in schools -- for 20 years. Their lobbying to reduce herbicide use led Caltrans to announce a goal to achieve an 80 percent reduction in the amount of statewide herbicide spraying by the year 2012 (in terms of pounds of active ingredients) from 1992 levels. Recently Caltrans announced it met an earlier goal of reducing herbicide use by 50 percent between 1992 and 2002."


    Here's a list (2010) of approved herbicides by Caltrans, in orange the dismissed ones, among them are Diuron and Oryzalin. Couldn't find any report like the 1999 study by CAT relative to recent years, btw.

  8. [~herbicide california roads] to find: Californians for Alternatives to Toxics and California Department of Transportation

    [Californians for Alternatives to Toxics]

    I wil continue the search!

  9. Missed the link to the list, here it is:

  10. California Dept of Pesticide Regulation Looks promising and on their Pesticide Use Reporting page is usage over many years. June 2013 will see the next report. But, I see these are listed by county...maybe Caltrans is hiding in there.


    1. Jon -- And how did you find these great resources? I'd like to see your method as well. What query led you here?

    2. Dan, I started with Ramon's query [Californians for Alternatives to Toxics] then clicked on LINKS which lists several dozen promising items amongst which were the 2 I posted. This only took a couple of minutes but without Ramon's CAT to start with it would have taken I think much longer. I was too busy to pursue it yesterday and knew it would have been solved by this afternoon.


  11. [california roads herbicides]

    [Pesticide Action Network Updates]

    1. Just how many pounds of herbicide are sprayed along California roads each year?
    Found Pounds used on Right of Way: 3,087,740 pounds in 2009.

    2. And, of course, just how toxic is this herbicide?
    A. From "Stop the Spray :: Herbicides along the Roadsides": Each herbicide product has different weather conditions under which it may be “safely applied.” Some chemicals in some herbicides are linked to prostate and breast cancer, other products/chemicals are linked to Non-Hodgkins Lymphoma.

  12. We first searched california roadside herbicide which gave us the name of the California Dept. of Transportation is Caltrans. Did a search caltrans roadside herbicide which led us to this site:
    From this site we learned that Caltrans sprays the roadside to prevent weeds, control fires, eliminate nonnative species of vegetation and to save money by not having to mow. We went back to our search results and found the site Reading this site we found that the names of the chemical products used and the problems they caused- Roundup, Aquamaster, Milestone and Garlon. It also gave us the name of the dept that regulates pesticide use- Department of Pesticide Regulation. We went to their website and from there we found a link for pesticide use stats. We clicked on 2010 the latest year available and found a link for top 100 sites and found that for rights of way (this does include alongside railroad tracks so it isn't just roadside but think it is close enough) the amount of pesticide/herbicide used is 3,366,150 pounds! We had found one site that stated that these herbicides caused prostrate and breast cancer but felt it may have been a slightly biased site so we then looked up the toxicity of Roundup. We found several authoritative articles the first being from Scientific American that discussed the toxicity to humans from the various ingredients in RoundUp.
    This search was fun and interesting and was especially relevant as a topic in school setting. This one took us less than 30 mins. to find. Again I did this search with my colleague Anne.

    1. The 3.366m lbs figure is alarming - the Office of Pesticides 2006&2007 Market Estimates report (most recent) indicate a total amount of Herbicide/Plant Growth Regulators use by Industrial/Commercial/Government users at 46m lbs for 2007 - table 3.4:
      (For reference, the CDPR figure for 2007 is 3.64: )

      Assuming that the Right-of-Way falls under the same category as Government use, and that only Herbicides are used for right-of-way, then Caltrans alone accounts for 6.5% of the annual Herbicide use in this country.

      California has a lot of Highway miles - and, at least for Northern California, lots of vegetation along those highways. Not as many as Texas ( [Highway miles by state] first result: ), but probably more that require vegetation control. But still, if the numbers do hold together, then 6.5% is a lot for a single state to consume.

    2. Niebylski this was for all rights of ways in California which it said also included railway rights of way. It is an awful lot of pesticides. And the use on rights of ways wasn't even the largest use. There was even more in some agricultural settings.

  13. What do I know?
    I know California has very strict environmental laws, especially vehicles.
    There would be an epa agency
    Query [california epa]
    Result -- no result
    Calfornia EPA Index -
    Department of Pesticide Contol
    Found pdf of annual pesticides sold in California. 21 page report. " Pesticide registrants, pest control dealers and pesticide brokers are mandated to report the total dollar value and total pounds or gallons of each product they sell for use in California." Doesn't specify highways but it totals 921 chemicals and 619,348,642.2 pounds sold in 2011. Also herbicides vs pesticides some refer to pesticides when it's herbicides. First 5 minutes so I will review further. But wow 921 chemicals.

  14. I followed the link gave by Unknown jon ( From there I followed their link to California Pesticide Information Portal (CalPIP, to generate a query.

    My search criteria:
    Site/Crop: RIGHTS OF WAY
    defaulted to Year: 2010

    A huge list was yielded. Saved it into a tablesheet and calculated some totals here:

    In 2010 alone, 2036967,354 pounds of product were sprayed, of which 935732,81 of chemicals (don't know exactly if this means that the rest are non-active elements). Of those, ROUNDUP PRO CONCENTRATE HERBICIDE is almost 1/3, with 774861,7333 and 388980,5901 of chemicals.

    No idea how toxic those are and it seems to me that, unless others have already studied the problem and published it (not unlikely, in fact), it will be a very long research and calculation.

  15. Erratum

    Correct link to my doc here, sorry:

    (I mistakenly converted the former one to csv, resulting in no formulae, only figures.)

  16. I have been searching for databases and using Google tables but nothing to submit so far. I would love the opportunity to use Google Fusions and produce some charts. If anyone is exploring this avenue as well let me know of your progress. Haven't explored the toxicity issued yet. My understanding of right of ways could include much more than roadsides such as future highways, utilitities, public lands etc. I will check in later.

  17. Query [ caltrans 2012 herbicide reduction]
    Pdf document -
    "Caltrans decreased potential pollutant loadings to the storm drain system and local waterways as part of its landscaping program. Caltrans applied 206,773 pounds of herbicide active ingredient, reducing the total amount of herbicides applied by about 39% during the fiscal year 2010-2011."
    Not confirmed elsewhere. No databases located (but I believe exist).
    As for dangerous or not I found reports on both sides. Caltrans has reduced usage which in itself at least acknowledges the need to reduce. They are exploring other options to deal with roadside vegetation other than chemicals. This issue is up for debate.

  18. [herbicide california highways] =

    [herbicide california highways] + Search Tools>Past Year =