If you were out around Buzzards Bay the weekend of September 12, you may have been surprised by some strikingly red water. It was part of a water-tracing dye study of the discharge from the New Bedford wastewater treatment plant.
The Federal Food and Drug Administration and Massachusetts Department of Marine Fisheries conducted the hydrographic dye study, which aims to better understand how discharge from the New Bedford wastewater treatment plant affects both shellfish and public health. A water-tracing red dye was added to treated wastewater to see where it goes and how it disperses.
Local oyster farmer Dale Leavitt donated oysters to the study. He’s interested in the results, as it could affect the shellfish classification of his farm in Nasketucket Bay. In 2024 his farm’s classification area was changed from “approved” to “conditionally approved,” which has led to significant closures. He said that change was based on a mathematical model that hasn’t been validated with hard data.
"This is a fairly important step in my mind," Leavitt said, "to actually looking at how effective that model was at predicting the dilution standards that are required for shellfish classification areas."
While the study was designed to only trace treated wastewater, a rainstorm during the study period triggered New Bedford’s Combined Sewer Overflow system. That released untreated sewage into the bay. And it’s those events that trigger closures for Leavitt’s farm.
Leavitt said that rain event could lead to another helpful dataset.
"We actually may get some data out of this that actually addresses the CSO issue as well as the plant discharge issue," he said.
Study results are expected to be released in 2027, and Leavitt says he's hoping it will be earlier rather than later.
"It’s gonna take a long time to get all the numbers together and compile all of it into a report," he said. "I was hoping like six months, but I’m sure it will be somewhere between six months and a year."
