Occasionally, on a dark quiet night, the streets of Brooklyn, New York’s Gowanus neighborhood, are the backdrop for an unusual environmental investigation. A middle-aged man and a teenage girl hunch over a closed manhole cover, holding a wire protruding from a small hole in it. This is Eymund Diegel and his daughter, Amara, his assistant on nocturnal explorations to sleuth the source of underground streams.

To do that, Diegel and Amara, 13, lower a secondhand lavaliere microphone — the kind television stations clip to lapels for interviews — through a small hole in the manhole cover. Using free iPhone apps, they record the sound level of the water flowing below. Diegel only listens at certain manhole covers, but his goal is to get readings for every hour of the day at each one.

Diegel is a board member for Public Lab, a nonprofit confederation of citizen-scientists dedicated to using open source hardware and software to bust polluters and other environmental bad actors. The organization first made a name for itself by mapping the BP oil spill’s impact on the Louisiana coast using hacked balloon- and kite-mounted digital cameras. Then it started making DIY kits that allowed people trying to solve environmental and community problems in other places, to use their basic aerial-camera technology. Their simple technique has helped people all over, including people like Diegel, who first became interested in the Gowanus Canal because of his passion for canoeing.

Diegel calls what he’s doing CSI: Gowanus. (CSI stands for “creek scene investigation.”) He says the underground streams he’s looking for were covered up as this corner of the city developed, transforming farmland into the concrete-skinned industrial zone it is today. The backbone of the neighborhood is the Gowanus Canal, a 1.8-mile-long industrial waterway and EPA Superfund site, the mere mention of which causes many New Yorkers to cringe in disgust.

The U.S. Environmental Protection Agency has plans to dredge the toxic sludge from the bottom of the canal and seal it off to prevent the deeper-seated pollutants from seeping into the waterway, but Diegel says he wants to make sure the job is done right. That’s where his CSI project comes into play. New York is equipped with a combined sanitary and run-off sewer system, meaning in times of overloading — like during severe rainstorms — sewage and storm water can both overflow into outlets like Gowanus. Diegel believes underground streams are, like rainstorm runoff, also overloading the city’s sewer system, pushing sewage into the already-polluted canal through the combined overflow system.

Where many people would write off extra water rushing beneath a manhole cover as human activity — toilet flushing, dishwashing and the like — Diegel noticed, thanks to his microphones, that water can also be heard at night, when most people are in bed. So he suspects the natural world has a hand in the problem. To find which manhole covers he should drop a mic into, he used an old digital camera mounted to a big red balloon, looking for large trees and unusually dense clusters of vegetation as close sources of water.

“We got the digital cameras from an e-waste center nearby,” Diegel says, adding that Public Lab distributes an open source hack script that takes over the camera’s operating system, making it possible to use it in a way its designers may not have anticipated, such as snapping pictures every 5 seconds while it’s aloft, dangling from a balloon. “Sometimes we hack the cameras to take infrared pictures, which are useful for spotting vegetation.”

Diegel does all this for free, in his spare time. But his day job is related: He maps potholes for the city’s department of transportation, and says that the places potholes are found often coincide with underground streams.

“The sinkhole that opened up in Brooklyn over the summer was at the headwaters of the Dyker Canal,” he says, referencing a long-covered waterway he had learned of by studying centuries-old maps. “The city said it was because of a water main break, but I wanted to know what had caused the water main to break.”

In addition to his informal field research — eavesdropping on sewers and knocking on doors and talking to people — Diegel relies on the data sharing and open source gadgetry championed by Public Lab.

“Open source also allows technology to become more accessible from a democratic cost perspective,” Diegel says. “Our consumer products, including those we use to view science and our neighborhoods are increasingly ‘closed black box’ products over which we have no control or input. We often don’t know how they work or how to repair them.”

Born From Outrage

Public Labs emerged in 2010, as outrage over the BP oil spill in the Gulf of Mexico began to mount. Its founders — a group of Gulf Coast residents, environmental advocates, and scientists concerned about the spill’s impact — wanted more detailed information about the movement of oil across the coastlines of Louisiana and other Gulf states. If the oil company was talking, they weren’t satisfied with what it had to say. They launched digital cameras into the air on balloons and kites all over the region, using software to stitch the images together and form a more complete picture of what was happening.

What started as grassroots mapping morphed into a long-term project to facilitate monitoring other problem areas. Public Lab has expanded farther afield, helping citizen-scientists map industrial pollution in Spain, air pollution in Ukraine, and forest canopy loss in Peru, among others. Thanks in large part to Public Lab’s collaborative spirit, the list of projects the organization’s techniques and open source kits have touched is seemingly endless.

“Public Lab is a large community, so it’s hard to say how many different things are going on,” says Liz Barry, Public Lab’s director of community development. “We try to count the number of environmental investigations underway, because that’s kind of the sum of all the community organizing that means people actually impacting their local environments.”

This kind of monitoring, and the equipment used for it, can be expensive and therefore difficult to access. The cutting edge in monitoring technology could certainly be helpful, but it only works if there’s someone who can use it. So Public Lab devises cheap hacks and open source software that’s accessible to all. The gadgets it relies upon for data collection include things like obsolete digital cameras, used DVDs, cardboard, and old soft drink bottles. When aerial photography is needed, Public Lab is much more likely to use plastic kites and helium-filled balloons than military-spec drones to carry its cheap camera equipment aloft.

Simplicity is the core of what Public Lab does, but so is sharing information. According to its website, Public Lab’s tools must be “low cost, open source, easy to use, built through public participation and collaboration, supported by a network of practitioners, [and able to] produce meaningful, understandable, and high quality data.”

Inclusive and Accessible

To give concerned citizens and community groups access to the tools they need to illuminate environmental problems, Public Lab sells low-cost DIY kits for everything from balloon mapping rigs to spectrometers designed to monitor water pollution.

“Our balloon kit was our earliest kit,” Barry says. “It’s been applied to a million different situations — oil spills, invasive species mapping, social protest.”

The kit contains, among other things, a neoprene balloon, a reel of fishing line, instructions on how to make a camera rig from a 2-liter soda bottle, rubber bands for the camera rig shock absorber, a grassroots mapping guide, and a balloon mapping flight checklist. Some cameras need to be modified to take pictures at five-second intervals, and others have a setting for that.

The interest in petrochemicals, which Barry says are a frequent player in environmental pollution scenarios, led to the development of the spectrometer kit. It started as a repurposed pizza box, cut up to hold an old DVD and a cheap webcam, then morphed into a DIY kit that could be purchased online. Public Lab says on its website that the materials to build a spectrometer cost less than $15. Detailed online instructions show how to cut up opaque black cardboard to make a small box, where to position the camera inside the enclosure, and how to peel the backing from a DVD-R and place it against a narrow slit to form a diffraction grating. Using a dimmable lamp to shine light through a water sample, an at-home scientist can measure light wavelengths down to the nanometer using Public Lab’s open source software.

The power of that measurement is in distinguishing hydrocarbons like oil and other contaminants. Public Lab is crowdsourcing a DIY method for that analysis with the help of chemists from its community. “The magic is in the collaborative environment Public Lab enables among so many different — and often siloed or unrecognized — forms of expertise,” Barry says, adding that academics are often happy to lend a hand. “The diversity in the type of expertise that is leading any given project is what keeps the barriers to entry low and keeps projects inclusive and accessible.”

Barry says it can be difficult to identify unknown contaminants, but as data comes in, it’s scrutinized by actual chemists and added to a database. The idea is to fill in the gaps, so to speak — to make it simpler to infer missing information from known values. “This could be like a Shazam for chemicals,” she says.

Other kits from Public Lab include a filter that helps convert digital cameras to infrared, a potentiostat to determine metal concentrations in water, and an Arduino-driven datalogger for a plastic water bottle that can record temperature, conductivity, depth, and turbidity in water.

“Temperature data has been used to shut down a nuclear power plant before, so a lot of communities are interested in that one,” says Barry.

Spreading the Word

DIY hacks aren’t the final answer in Public Lab’s battle against pollution, co-founder Matthew Lippincott points out.

“It’s not always about the gadget,” he says, adding that sharing information and telling community groups who to talk to are invaluable tools in the organization’s work. “Simple photos sent to an environmental health department can be really helpful.”

The pollution seen by a fisherman on Louisiana’s Gulf coast may share similarities with pollution on an industrial canal in Brooklyn, but there will invariably be differences in what works and what doesn’t. That, Public Lab participants explain, is why sharing information about process is as important as allowing each person to contribute his own input to each approach.

When a guy in a canoe who’s concerned about the water he’s paddling through wants to know more, he gets in touch with someone who knows what questions to ask, and how, and adapts them to his own situation. The same thing for a woman who smells oil fumes, but can’t figure out where they’re coming from.

By making it fun, with activities such as finding the “birthplace of the Teenage Mutant Ninja Turtles” (a nuclear waste pollution site in Queens), Diegel says he hopes to engage more people.

“Open source dialogues and the Maker ethos re-establish some of the fundamental building blocks for cultural evolution in our increasingly technology-dependent world,” Diegel says. “It’s also a fun excuse to fly big happy red balloons and kites, and meet interesting people doing cool stuff.”