From time to time, readers send us information about pesticides being used in “Natural Areas.” This time, it’s Pine Lake in Stern Grove… the same place where Imazapyr was used even before it was approved by the City. (It’s called Laguna Puerca on Google Maps.)

The pesticide is Aquamaster, i.e. glyphosate (similar to Roundup).

(Clicking on this picture will show a larger version.)

It came with this note (emphasis added):

What’s so natural about herbicides? Once again, herbicides are being sprayed in the Natural Areas, more specifically, Pine Lake. Don’t let your kids near the lake. Attached is the posted notice indicated spraying is “before 10AM” but I couldn’t see the date. When will it be safe for reentry? The sign says, “When dry.”  !!!!

Although most of us will agree that control of the aquatic primrose is desirable, mechanical removal, rather than herbicides, is the safer choice. The herbicide, Monsanto’s Aquamaster (i.e. aquatic version of Round-up) uses glyphosate as its active ingredients. Currently most studies support the safety of glyphosate. However, the controversy centers about the surfactants, i.e. chemicals added to glyphosate to make it adhere to the vegetation.

Here’s is a link to information about surfactants, in a risk assessment report for the Marin country Water District. The last pages of the chapter summarize the risks of surfactants, e.g. estrogenic effects on aquatic animals. For the most part, there is no scientific information or only sparse information on the risks.
http://www.marinwater.org/documents/Chap8_SurfDye9_2_08.pdf

Also, here is a link w/further information about herbicide use in SF Natural Areas Program.
http://milliontrees.wordpress.com/2011/04/29/concern-about-herbicide-use-legitimate-or-chemophobia/

As we’ve seen in other notices, someone forgot to fill in something — in this case, the date. As the writer points out, this makes it impossible to know when the pesticides were used and when it’s “safe” — presumably never, since it’s being applied “within lake” and will be safe “when dry.”

But still, it would be nice to know, from which date it will be unsafe?

(Also, we’d like to add that it’s not just the surfactants, though they’re definitely a concern. Recently surfacing research links glyphosate to birth defects.)

And… we hope Pine Lake isn’t Red-legged Frog habitat.

[ETA: We added more pictures from the same source. We’ve also been informed there are no Red-Legged Frogs. But there’s a kids’  daycamp adjacent to lake. (The picture shows the interpretive sign as well as the pesticide notice.)]