Monitoring Water Quality of the Hudson River

Lamont Doherty Earth Observatory has teamed up with Riverkeeper, an environmental organization that monitors and maintains the Hudson River ecosystem, on a program entitled, “Swimmable River,” to monitor the water quality of the Hudson River. Palisades resident Carol Knudson who has been working with LDEO scientists Greg O’Mullan and Andy Juhl on the project this past year gives us an update on the program.

Swimmable River started with a pilot study in 2006-2007, with water samples taken at 27 stations along the river. Funded by the Wallace Research Foundation, the program was extended through 2008. From May to October of last year, monthly samples were taken from 70 stations covering over 150 miles of the river from the Battery at the southern tip of Manhattan to the confluence of the Mohawk and Hudson Rivers at Waterford, NY.

Every year there are many cases of gastrointestinal illness that strike people who use the river for recreational purposes, such as swimming and kayaking. Enterococcus, a bacterium that is present in sewage-contaminated water, is responsible for many of these cases.

Sewage treatment plants all along the river have “CSO” (combined sewage overfl ow) systems. These systems combine sewage from homes and buildings with storm water runoff from the streets. Heavy rain and snow can cause these systems to overflow. They then discharge raw sewage and untreated storm water directly into the river. New York City alone has 460 sewer outfalls, which can discharge 27 billion gallons of raw sewage and polluted storm water per year into our waterways.

The situation has gotten better since the Clean Water Act of 1972 but many municipalities are still far behind in meeting this legislation’s requirement. Increase in development has exacerbated the problem by overloading already outdated sewage systems. In addition, once forests and wetlands are replaced by these impervious surfaces, the rainwater cannot soak into the ground as it should. The water then runs into the storm drains and floods the sewers, which cause the CSO’s to trip and pour sewage into the river.

The Lamont scientists monitor several different measurements in their monthly patrols on the R. Ian Fletcher, the Riverkeeper’s 36-foot “lobster style” boat piloted by Captain John Lipscomb. They have turned the boat into a floating lab where samples for Enterococcus can be prepared, incubated and analyzed on board. In addition to the discreet samples taken for Enterococcus and nutrients, there is also a Hydrolab sensor coordinated with a GPS unit on the boat, which continually measures surface temperature, salinity, oxygen concentration, suspended sediment and chlorophyll.

The goals for this project are not only to monitor, advocate better water quality policies and improve water treatment infrastructure, but also to give the public notification of river conditions in a timely manner. Previously, water quality data from state or federal authorities has taken months or years to be made public. This program is the fi rst to regularly test the Hudson River for these measurements and have the data publicly available within days. Check out for more information on this program and it’s results as well as other Hudson River issues. Refunding for the Swimmable River project for 2009 is still pending.