Researchers at UCSC and the California Department of Fish and Game have released a report suggesting that a toxin produced in local waterways could be contributing to sea otter deaths. The 3-year-study revealed that at least 21 recent sea otter deaths are due to exposure to microcystin. That’s a toxic algae that can buildup in freshwater sources. It has been detected in Watsonville’s Pinto Lake, as well as the Salinas, Pajaro, and San Lorenzo rivers, and near the Santa Cruz Wharf. The toxin attacks the liver, and although it is removed by water treatment procedures, the study raises questions over the safety of untreated water that is consumed by humans or animals. Reversing the buildup of algae could be aided by reducing runoff from leaking septic tanks, industrial agriculture, lawn fertilizer, and other chemicals.