Current weather-based estimate: 847 MPN. Latest lab result was 1331 MPN on Oct 1, 2026.
Site snapshot
Hackensack River, Dillards Memorial Bridge, Hackensack NJ
Hackensack River · New Jersey
High contamination levels
Historical medians: 269 MPN in drier conditions and 976 MPN in wetter conditions.
Middle lab-measured result across the site's full imported history.
Highest lab-measured bacteria level in the imported record for this site.
How to read this site
Enterococcus is a group of bacteria that normally lives in the intestines of people and animals. When it shows up at higher levels in the water, it can be a sign that sewage or other fecal contamination has reached that area.
It is used as an indicator organism, which means it helps flag the chance of sewage-related contamination without measuring every harmful thing directly. That makes it a useful way to track bacteria-based water quality conditions across many sites over time.
Lower numbers usually mean cleaner conditions for recreation. Higher numbers suggest elevated or high contamination levels, especially after rain.
MPN stands for Most Probable Number, a standard lab estimate of how much bacteria is present in a water sample. On this site, 35 MPN / 100 mL is the main reference point used to compare lower contamination levels with elevated results.
This is still only one part of water quality. These readings do not measure every form of pollution, and a single sample only captures one moment in time.
Today, based on recent rain
Best guess for the water right now
Likely high contamination levels
This site usually gets worse in the first several days after rain. Among this site's historical samples, drier conditions had a median of 269 MPN and wetter conditions had a median of 976 MPN.
Estimated bacteria level847 MPN
This estimate blends recent rain with the site's history. Below 35 MPN / 100 mL is the site's main cutoff for lower contamination levels during swimming or wading.
Threshold35
Estimate847
035140+
Based on this site's longer-term pattern plus recent rain near the shoreline.
Most recent rain near this site.
This is the main rain window used in the estimate.
No current water temperature feed for this site.
Historical trend
Bacteria level and preceding rain
Jun 2026 to Oct 2026
High contamination levels are common here across much of the record.
Lower is better. Colored bands show lower, elevated, and high contamination levels, and blue bars show rain over the same seven calendar days used by the model, ending on the sample date. Gauge readings take priority; Open-Meteo estimates fill gaps. Missing rain stays unknown. Hover for weighted rain memory and the earlier weekly totals used by longer-memory models.