Roeliff Jansen Kill

Citizen Testing Sites

Water Quality Conditions by Location

Recent Samples Historical Statistics
Site Name (Watershed) Sample Date [i] Entero Count

Entero Count

Enterococcus (“Entero”) is a fecal indicating bacterium that lives in the intestines of humans and other warm-blooded animals.

[i] 4 Days Total Rain (in)

4 Days Total Rain (in)

The combined rainfall for the day of sampling, prior day, two days prior and three days prior. More than 1/4 inch is considered a “wet weather sample.”

[i] Number of Samples

Number of Samples

Total number of samples included in these calculations.

[i] Geometric

Geometric Mean

A measure of central tendency (a weighted average) used by NYS DEC and the US EPA to assess water quality. The geometric mean is defined as the nth root (where n is the number of samples) of the product of the Enterococcus measurements. A geometric mean over 30 fails the EPA criteria for safe primary contact.

[i] Maximum


The highest Enterococcus count we have recorded at this site (“>” indicates an unknown number greater than this number and reflects the upper limit of our scoring ability for this sample).

[i] Minimum


The lowest Enterococcus count we have recorded at this site (“<” indicates an unknown number less than this number and reflects the lower limit of our scoring ability for this sample).

Individual Entero Counts by Site

Note: multiple counts of the same value will overlap and appear as one dot.

Water Quality*

Acceptable (0–60) Beach Advisory (61+)

*Single sample thresholds;
Enterococcus count per 100mL

Prior Four Day Rainfall
(in inches)

Dry Weather (0–0.25) Wet Weather (0.25+)

Geometric Mean*

Acceptable (0–30) Unacceptable (31+)

*Weighted average of multiple
samples; Enterococcus count
per 100mL

Stretching from Hillsdale to Germantown, the Roeliff Jansen Kill flows for over 54 miles, draining a 212 square mile watershed, located mostly in southern Columbia County, before discharging into the tidal estuary of the Hudson River at Linlithgo.

The headwaters of the Roeliff Jansen, some of which begin in the Berkshires of Massachusetts, come together in Columbia county to make it one of the largest tributaries to the Hudson River. The Roeliff Jansen Kill runs through beautiful rural farming communities in the upper watershed, before making its way through the alluvial plains of the Hudson Valley, and finally to the Hudson River where it serves as a critical habitat for migratory fish including alewife, blueback herring and American eel.

The river herring run ends at the stream’s first dam, located about six miles upriver at Bingham Mills, although the eel run continues upstream. This dam is considered a “Biologically Important Barrier” by the New York Department of Environmental Conservation, based on the presence of suitable migratory fish habitat, the stream condition, and the number of stream miles blocked by the barrier. Wild trout are present in the upper watershed, and the middle watershed is stocked with brown trout. Striped bass are also present at the Roe Jan’s mouth.

Read Riverkeeper’s 2019 Entero report for the Roe Jan Watershed.

Explore data from each sampling site, year-to-year patterns, and weather-related patterns for the Roe Jan Watershed.



Riverkeeper partners with the Roe Jan Watershed Community and Bard College Water Lab to conduct Enterococcus monitoring in the Roeliff Jansen Kill. RJWC has been testing for Entero since 2016. As of 2017, RJWC members sample at 16 points in the Roeliff Jansen Kill, its tributaries and the Hudson nearby. Entero samples are processed at the Bard Water Lab.

In 2017, the Roe Jan Watershed Community will also measure temperature, conductivity and turbidity at these 16 locations. The Roe Jan Watershed Community also does macroinvertebrate monitoring in coordination with the New York DEC WAVE initiative.

In addition to key partners Riverkeeper and the Bard Water Lab, the Roe Jan Watershed Community is grateful to Trout Unlimited both for advice and for critical funding, to the Columbia Land Conservancy, and also to the RJWC’s members whose contributions help make the program possible.

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