Cape Cod’s famed ponds and bays are suffering from pollution with a curious origin: human urine. Household septic systems are flushing nitrogen into the water, resulting in toxic algal blooms. In the second installment of our three-part Fascination series about Cape Cod’s “yellow tide,” environmental reporter Barbara Moran looks at the controversial and costly pollution solutions being considered. You can check out more of Barbara Moran’s reporting on the efforts to improve Cape Cod’s water pollution, including a “pee-cycling” project being considered by one innovative town. And watch WBUR and Scientific American’s documentary short exploring how pollution and algae overgrowth threaten this Massachusetts vacation hub. Email us at sciencequickly@sciam.com if you have any questions, comments or ideas for stories we should cover! Discover something new everyday: subscribe to Scientific American and sign up for our daily newsletter.  This series is a co-production of WBUR and Scientific American. It’s reported and hosted by WBUR’s Barbara Moran. Science Quickly is produced by Jeff DelViscio, Kelso Harper, Madison Goldberg and Rachel Feltman. Our theme music was composed by Dominic Smith. Shayna Posses and Aaron Shattuck fact-checked this series, and Duy Linh Tu and Sebastian Tuinder contributed reporting and sound. WBUR’s Kathleen Masterson edited this series. Additional funding was provided by the Pulitzer Center. Learn more about your ad choices. Visit megaphone.fm/adchoices