Fecal contamination can come from sources near the shore, like water sewer system outflows, or water birds. After sampling water from the creeks, the scientists use a DNA-based molecular tool called microbial source tracking. For this project, microbial source tracking has shown that there is likely more than one source of E. coli in the creeks. “Public water supplies are generally protected from the bacteria through well-established and proven treatment and disinfection techniques,” he said. “We will continue to conduct the microbial source tracking project to help figure where the contamination comes from,” Ren said.