Preliminary results from a beach sanitary survey by Tighe & Bond by Town of Marbletown identified pathogen pollution sources as primarily equine (horses), avian (birds), and ruminants (deer). Although enterococci levels were generally below DOH thresholds, severe wet weather events triggered spikes.

These results are comparable to what has been found in New York City watersheds. In an interview with the New York Times, commission of NYCDEP Rohit Aggarwala was quoted as saying, “The biggest source of [water supply] contaminants, even in a more heavily developed area like Westchester, is waste from wildlife, primarily deer.” He also said, “Storm water from extreme rain is flushing more contaminants into all of the city’s reservoirs.”

Riverkeeper tributary monitoring reports have also shown that “entero counts tend to be greater after rain.” Except for Marbletown beach, the source of the pathogens in the Lower Esopus have yet to be clearly identified. The results from the Marbletown beach sanitary survey cannot be generalized downstream along the rest of the Lower Esopus without further study. As the creek flows past developed areas, sewage may become a contributing factor if septic and wastewater treatment systems are not operating properly, but additional source tracking would be needed to make a determination.

So far, the main culprits appear to be livestock and wildlife. As a mitigation measure, riparian buffers could help absorb and filter stormwater runoff to improve water quality. Additional source tracking could better characterize the source(s) of contamination and help develop appropriate remediation and prevention strategies.