Pilot Program on Nitrogen Removal

A Cornell seaweed ‘farm’ will harvest excess nutrients from the tides

A water purification project in Accabonac Harbor — the first in East Hampton Town to be funded by the portion of the community preservation fund that voters approved last year for water quality improvement — is moving ahead, Kim Shaw, the town’s natural resources director, told the town board this week.

The project will make use of bioextraction, a natural process through which something is taken up by another organism, to remove nitrogen from the water. An excess of nitrogen, which leaches from septic waste, among other sources, leads to algal blooms, which severely impact aquatic ecosystems and can be toxic for humans. 

Macro-algae seaweed, which thrives on nitrogen, will be grown on frames set in the harbor. The plants on the frames will be periodically harvested and tested to see how much nitrogen they are taking up. 

Ms. Shaw told the board on Tuesday that it had “already been demonstrated that we have a serious nitrogen problem in Accabonac Harbor, through intense monitoring with Cornell over the past three years.” After winning a state grant, the town has been working with representatives of Cornell Cooperative Extension, which will oversee the project. Stony Brook University professors will join them next week in East Hampton, Ms. Shaw said. 

High levels of nitrogen as well as ammonia from urine that has not begun to chemically break down, have been recorded at the mouth of Pussy’s Pond as its waters enter Accabonac Harbor. A failing septic system at the Springs School, which has had to be pumped out regularly for years, has been targeted as the cause. The school has been repairing the system, which falls below current Suffork Health Department standards, however. 

As required under the legislation allowing 20 percent of the preservation fund to go toward water quality projects, the Accabonac initiative has been vetted and approved by a technical advisory committee. 

A similar macro-algae water purification project in Southampton Town has proven successful, Ms. Shaw said. Should the Accabonac project also be successful, there are plans to create another in Lake Montauk. “This is just one step toward the ultimate goal of reducing nitrogen,” Ms. Shaw said. 

A report is also to be made to the board next month on two other ongoing efforts to reduce water pollution, which employ different strategies. 

Permeable reactive barriers, buried structures that can capture contaminants in groundwater, are showing an 85 percent uptake of nitrogen passing through them, Ms. Shaw said, explaining that some have been installed around Three Mile Harbor.

Cornell also has been working on habitat restoration along the shore of Pussy’s Pond, using native plants to curtail erosion and provide a natural buffer, and Michele Carlson, a designer of sustainable landscapes, has installed bioswales there with plants that will filter contaminants from water runoff before it enters the pond and harbor. 

Also on Tuesday, the natural resources director reported that her department had accepted nine applications so far for the rebates the town is providing for the installation of improved septic systems that treat wastewater for nitrogen. The rebate program began on Friday. 

Owners of commercial and residential properties could be eligible for up to $10,000 or $16,000 in rebates to cover the costs of the new systems, based on location in targeted areas and on income. 

“We can come at this from two different angles,” Town Councilman Peter Van Scoyoc said at the meeting on Tuesday — reducing the amount of nitrogen going into waters while also using various methods to clean and restore already polluted water.

Clarification: The work done by Cornell Cooperative Extension at Pussy’s Pond included the installation of a permeable reactive barrier, along with water testing. Michele Carlson of Carlson Design and Planning has done the habitat restoration and native plantings there in order to curtail erosion and provide a natural buffer.