Algae that sucks oxygen out of the water is growing in the northern Gulf of Mexico. What’s left behind each summer is a colossal dead zone – a stretch of ocean where virtually no marine life can survive. This has fueled a debate about what we should be doing to the effluent we pipe into the river system. Thomas Granato, a scientist with the Metropolitan Water Reclamation District, and Albert Ettinger, a senior staff attorney at the Environmental Law and Policy Center, tell WBEZ science reporter Gabriel Spitzer what this has to do with Chicago.