Orleans project uses shellfish to reduce water nitrogen levels

MMA Innovation Award winner, From The Beacon, February 2018

As part of a three-year project that could pave the way to state approval of similar efforts, Orleans is using oyster farming to reduce nitrogen levels in a pond that has been declared an area of critical environmental concern by the state.

Nearby septic systems have created excessive nitrogen levels in Lonnie’s Pond, a saltwater pond feeding into Pleasant Bay on Cape Cod, resulting in eutrophication (oxygen depletion) and the Massachusetts Department of Environmental Protection declaration.

The pilot project uses 100 floating bags that hold an average of 5,000 oysters and hard-shelled clams that consume nitrogen, with the goal of meeting water quality standards and eliminating the layer of dead algae and sediment that prevents shellfish colonies from planting at the pond’s bottom.

“Because the DEP does not have a protocol in place that would allow us to rely on aquaculture to meet our nitrogen removal requirements, we’re embarking on this three-year demonstration project,” said Town Administrator John Kelly. “The goal of this program is to find a way to have this approved by DEP.”

The town’s comprehensive wastewater management plan previously had traditional sewering as the main approach to addressing nitrogen levels in local waterways, but Kelly said the costs of installing a sewer system throughout the community of 6,000 people proved exorbitant.

So Orleans has been working toward an amended management plan that incorporates non-traditional technologies such as aquaculture to alleviate the need for traditional sewering, which will save the town money and still clean the water.

The town is working closely with the DEP and the state Division of Marine Fisheries, which issues the town’s shellfish propagation permit. The town will produce a final report for the DEP that the state will use to determine whether the town’s approach can be an approved way to meet water body nitrogen removal requirements.

“The next step is to figure out how to take this aquaculture program and recoup the money with the removal of the [oysters and clams] and their potential sale,” Kelly added.