Raritan River Pathogen Monitoring Results for 9.11.2025

September 12, 2025

By Danielle Bongiovanni and J.M. Meyer

The second pathogen monitoring session of the month took place on Thursday, September 11th. Each week during the summer, from May to October, the Lower Raritan Watershed Partnership and Rutgers Cooperative Extension of Middlesex County run a volunteer-based monitoring program along the Raritan River. We collect water quality samples at six non-bathing public access beach sites, provide our samples to the Interstate Environmental Commission for analysis in their laboratory, and report the results to the public. Our mission is to share this data with the community and partners to ensure the safe use of the Raritan river for all.

Our lab results for water quality samples taken on Thursday, September 11th, 2025 show Enterococcus bacteria levels exceeding the EPA federal water quality standard of 104 cfu/100mL at three of our monitoring sites this week. Problem sites would be indicated by red frowns on the map and chart which includes: Rutgers Boat House (New Brunswick), Edison Boat Basin (Edison Township), and Ken Buchanan Waterfront Park (Sayreville). Riverside Park (Piscataway) had inconclusive results. Out of an abundance of caution, a red fown has been assigned to it. Green smiles on the chart and map indicate the sites with bacteria levels safe for recreation, and include the following: Raritan Bay Waterfront Park (South Amboy), and 2nd Street Park (Perth Amboy).

Pathogens/Enterococci levels are used as indicators of the possible presence of disease-causing bacteria in recreational waters. Such pathogens may pose health risks to people coming in primary contact with the water (touching) through recreational activities like fishing, kayaking or swimming in a water body. Possible sources of bacteria include Combined Sewer Overflows (CSOs), improperly functioning wastewater treatment plants, stormwater runoff, leaking septic systems, animal carcasses, pet waste, wildlife waste, and runoff from manure storage areas.

Our goal in reporting these results is to give residents a better understanding of the potential health risks related to primary contact during water-based recreation. If you are planning on recreating on the Raritan this weekend, make sure to stay safe and wash up after any activities!

Before pathogen monitoring can begin, the sonde is calibrated. Preparations include confirming the sonde accurately measures pH by submerging it in different buffers. The yellow solution is neutral with a pH of 7. Photo credit: Danielle Bongiovanni.
Our partners at the Interstate Environmental Commission provide us with thorough instructions on how to calibrate the sensors on the sonde. Rather than working off of memory, we prefer to have one person read the instructions aloud to avoid mistakes–in this, case Danielle is reading the instructions and recording the results of the calibration. Photo credit: J.M. Meyer.
Fishermen at Rutgers Boathouse reeled in a massive common carp (Cyprinus carpio), an invasive freshwater fish commonly found in the Raritan River. With it came a cigarette butt, illustrating how the trash tossed into the water does not instantly break down. Photo credit: Danielle Bongiovanni.
A happy fisherman with his netted carp. Our proximity to the river means people often fish before or after work. Photo credit: J.M. Meyer.
In Edison, as the tide rolled in, we witnessed no less than seven egrets riding fallen logs upstream against the current. Photo credit: Arthur Allgauer.
Gloves, sonde, and sample: John returns from wading into the waters in South Amboy. Photo credit: Arthur Allgauer.
The bottles used to collect samples are sterilized beforehand. The tape on the lid remains intact until a gloved volunteer is about to use it. This reduces the chance of contamination skewing the lab results. Photo credit: Danielle Bongiovanni.
In remembrance of Sepetember 11th, we stopped at the Middlesex County memorial in South Amboy. This eagle sculpture stares across Raritan Bay and across Staten Island — the Twin Towers were once visible in the distance. Photo credit: J.M. Meyer.
Beachgoers at 2nd St. Park deploy a seine net to catch fish and shellfish fishing for consumptions remains common throughout the Raritan watershed, and reminds us of the importance of keeping our waters clean. Photo credit: Danielle Bongiovanni.