Faecal bacteria monitoring in NYC waterways

In New York City, FreshWater Watchers are assisting with the sampling and analysis of urban waterbodies as part of study of the effects of sewerage storm overflows.

Normally, rainfall from small storm events is channeled into the combined sewer system and treated along with raw sewage before being discharged into local receiving waters. However, when the system becomes overwhelmed with storm water, it triggers Combined Sewer Overflow (CSO) events whereby waste water and storm water are released into nearby waterbodies without being treated first.

Concentrations of bacteria, such as E.coli and Enterococcus, which are indicators of faecal contamination and in waterbodies, have been shown to increase dramatically following storm events. Reducing the volume of CSO events is critical to improving the environmental quality of New York City’s waterbodies and expanding their recreational usage, and is part of the long term Mayoral plan.

In this project, bacterial concentration data will be collected from a wide range of sites over a number of years, on a fortnightly or monthly basis, as well as before, during and after storm events. These will be compared with rainfall measurements from several locations throughout the city, and the links between the two will be assessed.

The goal of the project is to accumulate a comprehensive dataset of bacterial concentrations essential to properly quantify the environmental impact of the city’s CSO system. This can then be used to develop effective measures to address the problem, raise public awareness of the issue and increase community support for mitigation strategies.

Lead Project Scientist: Dr Wade McGillis, Lamont-Doherty Earth Observatory / University of Columbia