Neighbor Leander discovered a Bernal Heights mystery recently:
My son and I walked all over south Bernal and noticed something odd: Every single storm drain has blobs of paint that look like balloons rising from the grating. The blobs are multicolored — red, blue and yellow — and most have long drips of white paint that look like balloon strings.
It was really strange. The first one, we thought someone had illegally dumped some paint down the drain. But they appear on literally every single drain we investigated.
Is it a strange art project? Some kind of construction signage, like the spray paint street hieroglyphics?
Or, another obvious possibility: Coded communications used by sewer-dwelling space aliens. Any other theories? Informed speculations?
UPDATE: Bernalwood readers are not only glamorous; they’re also wickedly well-informed. In the comments, we learn that these dots are markers used for San Francisco’s mosquito abatement program. Wendy McNaughton created the illustrated answer:
PHOTOS: Neighbor Leander
Bernalwood 
I’m pretty sure it’s to mark the drains for mosquito abatement.
I started seeing these dots appear when the West Nile Virus appeared in the Bay Area. I’ve seen people on bikes put stuff into the drains, and then mark it with the spray dot.
Yeah, I think that’s it.
That’s exactly right.
They’re to mark drains treated with mosquito larvicide.
http://mosquitosf.com/
Someone, possibly Burrito Justice, explained these at some point. If I recall correctly the different colors correspond to when the drain was last serviced/checked.
It’s the show mosquito abatement activity.
Cue the responses from the tinfoil hat brigade worrying about PESTICIDES being dumped into Bernal sewers! 🙂
Nope, it is the bikini jogger deflecting attention away from herself on the blog! 🙂
mosquito burrito injustice indeed
http://www.pbs.org/idealab/2011/03/how-dotspotting-began-with-colored-dots-on-drains-in-san-francisco066.html
and
http://mosquitosf.com/
Bernal Resident clears it up in this KQED podcast of a dramatization of the news story at the time, Sewermonster Diaries.
http://www.kqed.org/arts/programs/writersblock/episode.jsp?essid=21305
Todd,
Thanks for posting this up. And to Bernalwood readers for clearing the mystery up. My son will be relieved. He thought it was something to do with Pennywise, the homicidal clown.
Your son should listen to the above-posted short play podcast again, then.
Please read Stephen King’s “It” for creepy clowns in sewers
The answer of the paint marks on the street drains is quite simple and quite unremarkable. They are the identifying marks of the SF Mosquito Abatement service personnel who have treated that specific drain with their anti-mosquito chemicals & marked it with their coded color so another mosquito guy does not duplicate the treatment. I encountered a mosquito chap one morning on Cortland on the way to Martha’s and remarked what a silly form of graffti he was performing on a storm drain grate & he explained what he was doing. They are only one of the many unsung heroes of our urban world.
If you want, I can also explain what the mysterious white, locked stands are for? Like the one in front of the Library entrance on Cortland.
Mysteriously yours, Robert Kaiser
Oooh, I know that one. They’re for testing the water.
Wow, our mosquito abatement rocks. Here I was worried about paint being dumped to the Bay.
Those paint splotches are also used by city workers to mark storm drain vacuuming. Seriously. They have a huge vacuum they use to clean the storm drains.
now reading i know it has to do with the mosquitos but mY guess was that it was a melted jawbreaker left by one of the kids! haha i used to be safety patrol/student cross guard on that corner when i was in 5th grade. ahhh the memories