Student study finds bacteria levels high in part of brook
WESTPORT — Students from around Fairfield County found that Stony Brook in Westport had a few areas where the amount of bacteria tested surpassed the state criteria for what is allowed.
Students found that levels of indicator bacteria — e. coli and enterococci — exceeded the state limits at two of the most upstream sites of Stony Brook and at the most downstream site. However, the concentrations were below the state criteria at the three other sites along the brook students collected data from, said Mary Donato, Earthplace’s research and education coordinator.
“We test indicator bacteria concentrations as a way of determining the
likelihood that there are harmful pathogens present in waters that may affect human health,” Donato said.
The data was collected as part of the River Research Program offered through Harbor Watch at Earthplace. The students’ findings were recently presented at the program’s annual symposium and will be used in Westport’s pollution tracking project. Stony Brook runs through Earthplace and is a tributary to the Saugatuck River.
“These projects aim to find and eliminate sources of sewage pollution within waterways with the help of town partners,” Donato said, adding it’s a big part of how Harbor Watch helps improve Connecticut’s water quality.
Students have been studying Stony Brook through Harbor Watch for more than two decades. This year, 10 students, representing seven high schools in Weston, Norwalk, Fairfield, Stratford, New Canaan, Westport and Stamford, attended the six-week program, where they received experience in the field and in a lab, learned scientific techniques and analyzed data.
Students collected water samples from Stony Brook, beginning south of the Merritt Parkway and going toward the Saugatuck River. They monitored different parameters within it including indicator bacteria, dissolved oxygen, temperature and
pH levels.
Donato said the students found that average dissolved oxygen concentrations was generally within the state criteria at all of the testing sites, though findings differed
based on the season.
“Single samples at the most upstream site showed a drop throughout the sampling period and was increasingly below the criteria as the fall progressed,” Donato said.
“Students concluded that this was at least in part due to the more forested nature of those upstream sites — the decomposition of falling leaves can lead to low (dissolved oxygen) in the water — but noted that it was something that they believe Harbor Watch should keep an eye on.”
In general, water temperature and dissolved oxygen are connected, “as warm water can hold less oxygen,” Donato said.
She said this was something students observed in the fall and summer comparisons.
Students also found that the levels of bacteria at all sites along the brook were lower in the fall than in summer months, which Donato said is expected, as bacteria does not duplicate and grow as fast in cold water.
“We’re proud of them for their hard work and the confidence they showed during the event,” Donato said. “Many were presenting data in this format for the first time, which can be intimidating but they really gave it their all and the people who attended the symposium had great things to say about them. It was great for us to see their confidence building as the program and the symposium went on.”
This was the first year the symposium was back in person after it was held virtually the past two years, she said.
Donato said there are ways for people to prevent some of the pollution happening within their communities’ waterways.
For bacteria, she said it is important to pick up after pets who defecate while outside and ensure septic systems are up to date and correctly maintained.
For dissolved oxygen, Donato said, “Be responsible with use of fertilizers, and refrain from dumping or washing things into storm drains, which often lead directly to local streams.”