Expanded Bacteria-Testing of New Canaan’s Rivers Proposed

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Harbor Watch is hoping in 2019 to test for bacteria and hypoxia levels in three rivers in New Canaan, including the Silvermine, pictured here. Photo published with permission from its owner

Test results show that New Canaan’s waterways rank among the cleanest in the region, officials say.

At seven E. coli data-testing sites located on New Canaan’s stretches of the Noroton and Rippowam Rivers—sites each tested at least 10 times from May to September last summer—officials found that just one location had a bacteria level that failed state criteria.

And that one location—along Ponus Ridge, just below Collins Pond—was only “marginally failing” and within the margin of error, according to marine ecologist Dr. Sarah Crosby, director of Harbor Watch.

“I am not overly concerned about there being an acute problem,” Crosby told members of the Conservation Commission during their regular meeting, held April 11 at Town Hall.

Asked why New Canaan appears to have cleaner waterways than other towns in Fairfield County, Crosby said “a lot of it has to do with keeping infrastructure up-to-date.”

“A lot has to do with public understanding of things like septic maintenance, and the town regulations around septic systems can have a big impact, and then land use is a big part of it as well,” she said. “But infrastructure in most of the places we work is the major driver of these kinds of pollution sources, so it probably means that Public Works is doing a good job.”

Her comments came during a presentation on river water testing. Part of Westport-based nonprofit organization Earthplace, Harbor Watch is dedicated to improving “water quality and ecosystem health in Connecticut,” according to its website. Last year, Harbor Watch monitored 20 rivers in 17 towns in Fairfield County, processing more than 2,500 water samples, according to an annual report.

Crosby said Harbor Watch bolsters state and local data-gathering efforts and works with municipalities to address troubled areas, such as identifying high levels of E. coli, which may indicate the presence of more harmful pathogens.

This year, Harbor Watch is hoping to find local partners to expand its program in New Canaan to include more monitoring and “track-down” work, Crosby said.

“We try to not only conduct this baseline monitoring to see where the problems may be, but also go that next step and work, for example, in the stormwater system manhole-by-manhole through those pipe networks to determine exactly where the pollution source might be coming from,” she said. “Or house-by-house working on a granular scale up each river until we determine the likely source of pollution.”

Harbor Watch is planning to test not only the Noroton and Rippowam Rivers but also the Silvermine RIver, and also to focus on the southern areas of the Fivemile River, she said.

In addition to Conservation Commission Chairman Chris Schipper and Commissioner Linda Andros, First Selectman Kevin Moynihan, Inland Wetlands Commission Chairman Dan Stepanek and New Canaan Land Trust board member Beth Sanford attended.

Schipper said he was hopeful that the Conservation Commission could help support Harbor Watch’s testing and also that local public works officials have said they’re interested in partnering with the organization to get testing done.

During the meeting, officials asked Crosby whether river water that met the state’s criteria for E. coli testing meant it was drinkable (no), how much of an effect the Clean Water Act had on pollution loads (enormous) and whether putting salt or sand down on the roads during the winter affects the quality of waterways (that can have different impacts though Harbor Watch doesn’t test specifically for it). 

Crosby said she was excited to be in New Canaan because “things are generally pretty good and we tend to focus where things are pretty bad.”

“With that said, it’s really important to keep these data records going because we won’t know if things are starting to look bad unless we are collecting the data,” she continued. “Things can look perfectly healthy and be absolutely full of sewage. And I have experienced that firsthand, where I will go to a site and everything can look fine but we get the results in the lab the next morning and there is something happening right there.”

Areas “downriver” from New Canaan’s portion of waterways that feed the Long Island Sound—in Darien, Norwalk and Stamford, for example—tended to have far higher bacteria levels than here, according to Harbor Watch’s data. Schipper said it was important for the efforts of those municipalities to improve water quality to succeed so that fish are healthy and abundant, and can swim upstream into New Canaan.

Here’s a snapshot of 2018 data for the two rivers in New Canaan that Harbor Watch tested. The “geomean” measures “CFU/100 mL” or colony forming units per 100 mL, a measurement for bacteria concentrations. The state Department of Energy and Environmental Protection criteria calls for less than 126 CFU/100 mL for the E. coli geomean.

River Testing Results, New Canaan (2018)

River and test sitesE. coli geomean
Noroton River
Site 566
Site 7114
Site 8123
Rippowam River
Site 989
Site 10130
Site 1151
Site 11.585
Site 12102
Source: Harbor Watch


Historical data and more specific information on sites can be found here.

The Fivemile River last was tested in 2017, Crosby said, and three test sites in New Canaan failed that summer “so I am interested in hopefully making connections through this meeting so that we can try to do some track-down work in the vicinity of those sites and collect some more baseline data there.”

“There wasn’t an obvious source of those problems, and just because because a site is failing doesn’t mean there is a sewage pollution problem, because you can get elevated E. coli levels from things like geese or other animals in the water as well. So, it does not necessarily mean that there is a sewage problem, but there is a bacteria source, so making sure we can rule out sewage that could be harmful to people would be important.”

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