Citizens' Water Quality Testing Pilot Program, Fall 2011

This pilot program lasted six weeks and volunteers collected test samples at sites up and down the Hudson and in the Brooklyn Navy Yard.

Water quality is a concern for swimmers, kayakers, and all others who come into contact with the waters of the New York / New Jersey Harbor. According to a survey by the New York City Water Trail Association, more than 40,000 individuals paddled or rowed in the harbor in 2009, often with exposure to the water via splash or capsize. Last summer's large and unexpected sewage releases from the North River treatment plant raised awareness of the issue, and some of the harbor's users have developed an interest in citizens' water-quality testing, to supplement the information available from traditional sources, like government agencies. Recently the Water Trail Association and the River Project conducted a pilot program to study the feasibility of such testing and to learn the basic issues involved.

Scope of the Testing

What was tested: Water was sampled at a dozen near-shore locations in the harbor and was tested for the presence of Enterococcus, a type of bacteria that is widely considered the best indicator of mammalian sewage, especially in brackish waters. The tests were performed with an industry-standard kit and protocol from Idexx, the same system that Riverkeeper uses.

View 2011 NYCWTA Citizens' Water Quality Testing Pilot Program in a larger map

Where the water came from: Mainly from human-powered boat launches along the Hudson River, at Yonkers, upper Manhattan, Harlem, midtown Manhattan, and downtown Manhattan. Also from the East River, at the Brooklyn Navy Yard.

Who took the samples and did the testing: Volunteers from NYCWTA member organizations took the samples. Professionals and interns at the River Project did the testing. A combination of those people transported the samples to the River Project’s lab on Pier 40.

When was the testing done: Roughly once a week, from mid-October to early December, 2011. Conclusion: We decided that a longer-term citizens' program of water-quality testing is feasible, after obtaining money for the tests (which cost about $15 each, in addition to one-time costs) and after making changes to our procedures based on what we learned.


We present the data from the pilot below, but we do not believe that it provides an adequate basis for making practical decisions about water quality. Here are the limitations we know of:

(1) The data covers too short a time. We cannot reliably discern, from just a few weeks' results, predictive patterns of contamination and their relationship to other factors, like wind, currents, rainfall, and tides.

(2) We didn't include enough control tests. In the future we need a systematic set of controls that includes duplicate samples from a given site in quick succession, duplicate analyses of two doses from the same sample jar, and analysis of water known to be clean. Such controls would let us better estimate the error in our results and would assure us that our handling doesn’t contaminate the samples.

(3) Our procedures had weaknesses that might have decreased the reliability of the results, including inconsistencies in sampling containers and in times at which samples were taken, the temperature of the containers during transport, and the manner of sealing the analysis trays.

(4) We haven't correlated the test results with other site-specific data that might be relevant, like water temperature, turbidity, tidal levels and currents, wind and waves, and localized rain events.

Future Directions

We hope to get funding and volunteers for a season-long testing program in 2012. We would like to expand our scope to other sites around the harbor, and we would like to find partners who can help with collection, analysis, transportation, and funding. We will probably work out more efficient ways of transporting the samples, and we will change our other procedures in accordance with what we learned in the pilot. The basic organization will probably remain unchanged, though: volunteers will take the samples every week; the samples will be transported to the River Project at Pier 40 (Houston Street and the Hudson River); the River Project will do the lab work; and the results will be analyzed and reported each week.

We need to look into how to convert our data into practical decisions -- for instance, what kind of bias and randomness we should expect in our results, given our procedures, and which EPA standard (or other standard) we should compare to. To make accurate decisions, harbor users need to know what local conditions -- like current and rainfall -- affect water quality. We see the value of studying such correlations, but for reasons of feasibility, we expect to leave most of this work to boathouses and other harbor users with specific knowledge of conditions at their launch site. Our consideration of practical decision-making will be part of a larger conversation about water-quality standards -- whether we want or need them, who ought to be setting them, and whether they ought to be different for different kinds of boaters, boats and programming.

Click here for results from the pilot program.