How Dotspotting Began with Colored Dots on Drains in San Francisco

by Eric Rodenbeck
March 15, 2011

i-8d9efa4c44f4045a6b5ead47237c9cec-sewer-250-thumb-250x252-1848.jpgIn some ways you could say that the Dotspotting project started with San Francisco’s sewage and drain system. A few years ago I started noticing some strange dot markings on the curbs of city sidewalks, directly above the storm drains like the one you see on the left

But on closer inspection, it turned out they weren’t just single dots. They seemed to be dots that had been applied, rubbed off a bit, and reapplied. Like Roman palimpsests, the curbs above drains looked like reusable canvasses — but for dots, instead of edicts. The image below is one close-up example.



This is the kind of thing that infrastructure dorks like me obsess over for a while… and then inevitably move on to something else. (My fascination with the dots waned as I became intrigued by another piece of urban infrastructure, the cable car, which I’ve been using on my daily commute for about six months — and mapping on Dotspotting).

Spotting the Dotter

A few years went by and one day I happened to see a man riding his bicycle down Hyde Street in the Tenderloin. His route and mine coincided in just the right way for me to see him stop at a storm drain, reach down and do something with a pole, make a note on a hand-held device, and slowly bike down to the next drain. Traffic being what it was on Hyde, I was able to catch up with him just in time to see him spraying different colored dots on the curb, over dots the ones that were already there! I was pretty excited.

After a quick conversation later, I discovered that he worked at San Francisco’s Mosquito Abatement Team. This is the part of the Public Utilities Commission that checks likely standing water locations in the city and, if they find mosquitoes, deals with them. Of course, they track all of their work on GPS and so forth (stay tuned for some hopeful mappings of that data).


But in order to keep things simple — and to make it possible to see how long its been since a drain was inspected — the Abatement Team coordinates their efforts so that they always know whether this inspection period is green, white, pink, and so forth. If a drain’s most recent dot is the right color, it’s been inspected. If not, it hasn’t. It’s a simple and elegant solution to a potentially onerous problem.

I love that the simple process of making the same mark over and over again, but making it slightly differently, results in this rich data set that can be understood and read if you’ve got the information and tools to interpret it. (As a side note, I also love having conversations with people who spray markings on the sidewalk. You think you’re bothering them with your questions but I’ve found they’re actually pretty pleased to talk to you.)

Visualizing Water Systems

Like a lot of other things, the water system is a gnarly beast that gets more interesting the more you poke at it. There’s a ton of information available on the San Francisco utility website, including the awesome map of its wastewater system below — it even includes the city’s version of the Continental Divide:

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Back to Dotspotting

All of this is a long lead-in to the fact that Herb Dang, who runs the Operations department at SFWater, was a surprise visitor to the CityTracking Conference we’ve just finished cleaning up from at Stamen HQ. His presence sparked just the kind of conversation I had hoped would happen at the conference: developers interested in digital civic infrastructure talking directly with the people who hold the data and use it every day.

We learned a couple interesting things from Herb.

First, that there’s a giant concrete wall around the city on the Bay side that channels all of the wastewater runoff down to the Southeast Treatment Plant (not to be confused with the Oceanside Treatment Plant that was almost renamed the George W. Bush Sewage Plant. (“Besides,” locals joked, “if we name the local sewage plant after Bush, then what’s left to name after Jesse Helms?”)

Second, that any request for data about the location, diameter, and any other information about a public drain pipe in the city has to go through a technical review as well as a legal review. So, in addition to needing to verify that the information is correct, the water department also needs to verify that it’s a legit request. You don’t want people hoovering up information about drains that they could potentially slip bombs into, for example.

Every single building in San Francisco has their own set of records for water and drainage and sewer connections, and getting information on each one of these generates its own review processes. What that means is that if a team like Stamen wants to make a map of the water infrastructure near our office, we’ll need to write a separate subpoena, for each connection. For. Each. Connection.

Herb estimated that, within a stone’s throw from the studio where the conference was held, there were about 40,000 sewer connections. “40,000 subpoenas” became a catch-phrase for the rest of the day.

How We’re Implementing This Info

In any event, I’m still catching up with all of the interesting discussions that were had during the conference, but that’s a pretty good representative sample. It’s also a nice way to segue into the design work we’ve been doing on Dotspotting, which I’ll be demoing briefly at South by Southwest this week.

There are a number of pretty substantial improvements, but what I’m most excited about at the moment are some big changes to the interface and overall visual look of the thing. Mapping 311 requests for Sewer Issues in District 10 used to look like the cropped image below.

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Now, with some swanktastic custom cartography that Geraldine and Aaron have been working on, and visual and interactive improvements that Sean and Shawn (I know, weird, right?) have been polishing and making right, it looks more like the shot below. We’ll be pushing this work live some time before my SXSW presentation.

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So, onwards we go. Upload yer dots!

Tagged: citytracking data visualization dotspotting government records san francisco wastewater
  • Shaun Reen

    Thank you. Very interesting. I’ve wondered about this for years as I walked my dog (no, I do not use the drain for his refuse). And then yesterday I saw a kid doing the marking (here in NYC). Rather than ask him what he was doing, I looked it up here. Now I can’t wait to see him again and ask him if he knows the history of what he’s doing (yeah, I lead a very exciting life).