One Murky Water Mystery Solved

“Find out what is happening with the water at Pear Tree Beach.” That was one of the first tasks that the Board of Selectmen put before David Knauf, after appointing him Director of Health back in September of 2008. And just over a year later, Knauf reported back to the board with the answer.

For a coastal town like Darien, frequent analysis of beach-water quality is vital to protect the health of the community, particularly during the summer months when swarms of residents flock to the beaches to swim. A high bacteria count is cause for a beach closure, and in the summer of 2008, the Health Department closed Pear Tree Point Beach more than once. Thus, the mystery of the murky water became a cause for concern.

Knauf presented his findings to the Board of Selectmen at their meeting Nov, 23. “What is happening with the water at Pear Tree Beach,” is a result of the high bacteria level at Gorham Pond; and the high bacteria level at Gorham Pond is the result of outdated septic systems that, at high tide, flush straight into the pond and on to Pear Tree.

With help from an intern this summer, Knauf organized and analyzed all the water-sampling data that had been collected since 2002. The goal, he said, was to assess the “health” of Darien’s marine waters and to amend the town’s existing policy for closing the beaches as and where necessary.

“There were a couple of major findings,” said Knauf.

One of those findings was a detectable amount of chlorine in Gorham’s Pond. Knauf’s longitudinal study shows consistently high levels of bacteria in the pond, Pear Tree’s main freshwater input located just north of the beach, and this year was no exception. In July, levels of Enterococci (ENT) were well above what is considered safe for swimming. Based on the pond’s water-quality history, that came as no surprise. What was a surprise, said Knauf, was the chlorine discovery.

“When we went back in August, the bacteria was gone,” said Knauf. “The analyst at the Stamford Health Department said the water smelled funny, and the sample tested positive for the chlorine.”

Chlorine is not a naturally recurring element, said Knauf, so it must have come from elsewhere.

“I doubt it’s from swimming pools, because the pond is quite large.”

Selectman Callie Sullivan (D) asked of the impact chlorine might have had on wildlife. Knauf said that aside from killing bacteria, the negative effects on wildlife were few.

“The egrets were a little whiter than they had been,” he said.

Both Knauf and the Selectmen have their hunches as to how the chlorine might have got into Gorham’s, downtown property drainage issues among them. But for now, the chlorine incident remains a mystery.

 “What I thought a much more definitive smoking gun is what we do with 50-plus-year-old septics that are near the coast,” said Knauf

It’s the old septic tanks serving the surrounding homes of Gorham’s Pond that Knauf says may well be responsible for a high bacteria count at Pear Tre. Case to his point: The Goodwives Final Water Management Plan (WMP) of 2004. According to the study, nearly 80 percent of Darien is served by sanitary sewers, and most of them were installed between 1938 and 1972. Many of these septic systems may be subject to a high water table and during times of consistent rainfall, said Knauf, could drain into the pond.

“It would appear that during low tides, the water from Gorham’s Pond flows out into the Pear Tree Beach waterways and has the ability to spread bacteria,” said Knauf.

While not considered “smoking guns,” there are other contributing factors to the high bacteria count in the water at Pear Tree like heavy rainfall, tides, and the lack of vegetative buffers that can serve as “bacteria storage.” Furthermore, Gorham’s Pond is a highly impacted water system.

“It drains the entire downtown area of Darien as well as a significant portion of I-95,” said Knauf

As for amendments to the existing “Darien Health Department Policy and Protocol for the Operation of the Town Beaches Bating Area(s),” Knauf recommended closing Pear Tree Beach whenever the floodgates to Gorham’s Pond are Open. Adding signage that encourages swimmers to swim and towel off as soon as possible was another suggestion. But most notable was the proposition—endorsed by Public Works, the Sewer Authority, Health and the Board of Selectmen—to get rid of the septic tanks.

“The abandonment of substandard septic systems and connection to sewers could be the single most important measure the Town could take to improve water quality at Pear Tree Beach,” reads the policy change.

But the murky water mysteries should not cause too much concern, Knauf said.

“Overall the quality of the water is good,” said Knauf. “But we’re concerned about the septic tanks.”