When PhD student Ibrahima Diagne has to take a sample of the wastewater flowing from Dakar’s drainage canals into Hann Bay, he does the smart thing: Diagne sends the master’s student who came with him to do it. On a recent morning, that student, Cheikh Tidiane Dione, rolled up his pants, tied plastic bags around his hands, and got to work in the cloudy water, careful to avoid the trash that accumulates around the canal’s opening. As he took the sample, a woman came by with a bucket of her kitchen scraps and tossed them straight into the water. Further down the beach, Dione took a sample from another canal that runs black and thick with something viscous—oil, Diagne hypothesized—combined with fecal matter. In the opposite direction, a different canal releases malodorous wastewater from an industrial zone that includes several food companies and a tannery. The bay receives wastewater from many industrial sources, including chemical companies, an abattoir, and an oil refinery. More than 10 years ago, Marc Bouvy, a researcher with the French Research Institute for Development (IRD), undertook a study of bacterial contamination in the bay.1,2 He says that several pipes from industrial sources released unknown pollutants, including one that “one day released red wastewater and other days released waters that were green and yellow.” Once a sparkling jewel with white sand beaches, Senegal’s Hann Bay is now severely polluted with untreated sewage, industrial waste, and more. Researchers are studying what’s in the water, how it’s affecting life around the bay, ... These are just a few of the many outflows that stream into the bay, a stretch of beach that runs from the industrial port of Dakar about eight miles to the outskirts of the city. All of them, the canals and the pipes, have been pouring their waste into the bay unimpeded and untreated for years. Now researchers are filling in details about what’s polluting the waters of the bay and how to mitigate the problem.