https://phys.org/news/2018-07-methods-recreational-quality.html

Recreational waters can harbor an array of different bacterial pathogens, the investigators noted in their paper. Human fecal pollution is the biggest concern for public health, as there is no inter-species barrier to transmission to humans. "But other fecal sources that contain enterococci and possibly human pathogens can be chronic or intermittent sources of both, making beach water quality management and remediation efforts more complex," the investigators wrote.

Dr. Jones and his student and coauthor Derek Rothenheber, collected water samples weekly at Wells, Maine, during the summer of 2016. In 2014, two of the town beaches had been flagged for intermittently exceeding state standards for concentrations of enterococci, and advisories had occasionally been posted warning the public that the waters might be unhealthy—bad publicity for a beach town. But by 2016, the Wells Beach area was meeting state of Maine standards.