Brazilian activist and fisherman Alexandre Anderson uses one hand to steer his boat, and the other to film an oil stain spreading over Rio de Janeiro’s Guanabara Bay. He will upload the video to an app developed to expose environmental damage in the iconic bay crucial for tourism and the fishing industry, but plagued by spills of oil, chemicals and untreated wastewater. Guanabara Bay, a natural port of about 400 square kilometers (154 square miles), battles pollution not only from visiting vessels and oil rig accidents, but also from old ships abandoned in its waters and runoff from cities. Frustrated with what they see as a lack of official response, the bay’s fishermen decided to take matters into their own hands, and with the backing of non-governmental organization 350.org, had an app developed for them. “We used to take pictures with our cell phone or a camera,” but without exact geolocation data, it was of little use, Anderson — president of the bay’s Ahomar fishermen’s association — told AFP as he filmed a steady stream of wastewater being dumped from a ship. The app, however, “gives me the precise” data with which to file a complaint, anonymously. The information is verified by a moderator and published on a dedicated website, after which it is reported to authorities such as the country’s Ibama environmental regulator or Brazil’s navy, which patrols the bay. Every time he monitors the dark waters for just a few hours, Anderson encounters several illegal spills, he says. Within three weeks of the app launching on July 26, 20 complaints were posted on the web, and more than 100 others are under analysis, according to administrators. “The inspection agencies always claimed they don’t have the tools to deal with complaints,” said Paulo Barone, who belongs to another local fishermen’s association.