Pathogen contamination in the Hans Groot Kill, Schenectady, NY

Streams in urban areas with aging infrastructure may become contaminated by sewage and stormwater runoff as underground piping breaks down, thereby contributing contaminants to larger rivers. The Hans Groot Kill (HGK) is an urban stream that runs through the Union College campus and the General Electric Realty Plot to the east. The HGK is one of many tributaries to the Mohawk River, and it is a classic example of a stream suffering from urban stream syndrome. Today, only 1.2 km of the HGK is above ground; upstream and downstream ends of the HGK were buried in pipes during urban development of Schenectady in the early 1900s. The upstream end of the HGK is located at the meeting point of three large stormwater pipes that collect stormwater from neighborhoods to the east and northeast of the GE Realty Plot. The downstream end of the HGK is buried in a large pipe between the downstream end of Jackson's Garden and the confluence with the Mohawk River. Due to these changes in channel morphology, the main water source of the HGK is now piped stormwater runoff. Prior research showed that the HGK is contaminated with microplastics, which suggests input of domestic sewage, including laundry wastewater. For a year, I collected data on water properties, including specific conductance, from the HGK using a YSI multi-parameter handheld field device. The SC values were relatively high, indicating high levels of ions in the water and suggesting contamination. To determine whether the contamination included sewage, 251 HGK water samples were collected between April 2019 and March 2020. The water samples were analyzed for fecal indicator bacteria, mainly Enterococci, using the IDEXX system in the Geology Department. Analytical results showed that Enterococci levels in the HGK exceeded EPA guidance for fecal indicator bacteria in all but one of the 251 samples. Enterococci levels in HGK water typically exceeded EPA guidance by orders of magnitude. Enterococci values rose with heavy rainfall, further pointing to sewage input to stormwater as a cause of the contamination. The results implicate leaking and/or illegally connected sewage pipes as a source of the pathogens in the HGK. A stakeholders group that formed in response to these findings drew regulatory and municipal attention to contamination in the HGK, and the first steps of the remediation process (sampling to establish whether the fecal indicator bacteria are human) are underway at the City of Schenectady and NYS DEC.