ConCom Weighs Evidence For Oyster Filtration Progress

By: Ed Maroney

Topics: Wastewater treatment , Waterways

Bags of oysters at Lonnie's Pond are part of a nitrogen removal experiment that could limit the need for sewering in Orleans.  ED MARONEY PHOTO

ORLEANS If 50 million Frenchmen can't be wrong, can a million oysters be just right?

Town consultant Science Wares planned to file Feb. 14 with the conservation commission for review of a potential second stage of the oyster filtration pilot project conducted last year in Lonnies Pond. Sia Karplus of Science Wares and Dr. Brian Howes of the School of Marine Science and Technology at UMass Darmouth spoke with commissioners Tuesday about initial results.

Data from the 200,000 various-sized oysters harvested and examined after months of floating in the pond showed a significant uptake of nitrogen, removing some from the water column and some from bottom sediment. It's another sign that Orleans might be able to meet federal and state nitrogen removal levels for its waters with something less than an expensive town-wide sewer system.

With similar projects underway on the Cape in Mashpee, Barnstable, Wellfleet, Falmouth, and Harwich as well as elsewhere on the East Coast, Howes said, “We're in a 'show-me' stage so towns can get credits toward their EPA-approved TMDLs (total maximum daily loads of nitrogen).”

A written report to the town indicates that “even the limited oyster deployment in 2016 generated a lowering of key eutrophication indicators associated with the oysters held within the southern region of Lonnies Pond. Based upon these results, confidence is greatly increased that an expanded oyster deployment will improve water quality within this eutrophic estuarine basin.”

While grateful for the detailed report, commissioners questioned Howes closely on potential downsides, including a potential “catastrophic failure” of the oysters that might add more nitrogen to the pond. Karplus noted that the oysters would be pulled out as part of the project. Walter North urged the researchers to watch for any potential effects on other pond life, and wanted to make sure that the overall work had been peer-reviewed by other scientists. Howes said his group is under a four-year contract with the federal Environmental Protection Agency to study the potential of such projects. “That's all peer-reviewed,” he said. Selectman Alan McClennen added that his board is pursuing a peer review as well.

If the second phase of work is approved, Lonnies will host the million oysters on one of its 15 acres. Extensive water monitoring will continue, including surveillance of inputs from Pilgrim Creek and a nearby cranberry bog.

“There are so many variables,” commissioner Judith Bruce said. “It's not your typical science experiment.” She urged the consultants to present their findings as simply as possible. “We're not all scientists,” she said. “We need to understand and buy in.”