To prevent harmful algal blooms, which can be potentially dangerous for humans and have in the past been fatal for fish, the Southampton Town Board and the Southampton Town Trustees have authorized a $434,000 project for the remediation of Water Mill's Mill Pond.
The beleaguered pond, which was the site of a massive fish kill in 2008, will be given an application of Phoslock, a proprietary substance that mixes the Australian-mined rare earth element lanthanum with benthic clay. Phoslock is designed to capture phosphorus, a nutrient that algae feeds on. Phosphorus, from septic systems and fertilizer, gets to water bodies through the groundwater and stormwater runoff, and when there is too much of it, algal blooms may occur.
Earlier this month, the Southampton Town Trustees, who oversee water bodies in town, approved the expenditure of $50,000 for the project, and the Southampton Town Board agreed to kick in the other $384,000.
The trustees also report having already spent $250,000 on tests, to satisfy the New York State Department of Environmental Conservation, which issued a State Pollutant Discharge Elimination System permit for the project.
“This is the first serious implementation of water remediation in the town of Southampton," Trustee Fred Havemeyer said.
The trustees previously cordoned off a channel of Mill Pond last year to test Phoslock, and Havemeyer said that, after the successful trial run, they are ready to try it on the whole 87-acre pond starting the first week of April. The four-day process will be the first Phoslock application in New York State, he added.
"The Trustees have been conducting tests for the past five years and interviewed a number of contractors and pond consultants to determine the correct process to clean up the pond," Eric Shultz, the president of the trustees, wrote on the trustees' Facebook page. " The Phoslock product will be imported from Australia where it has been used successfully for years in large government projects."
The substance will be spread over the pond, and will capture phosphorus as it settles to the bottom. Havemeyer said the clay will create an invisible film on the bottom of the pond that will prevent the phosphorus from getting back into the water, and if the bottom is ever disturbed the Phoslock will recapture the nutrients and settle to the pond floor once again. The Phoslock will keep working for two to three years, he said.
April's application is about two-thirds of the total treatment, Havemeyer said; the final third will be applied in March of 2014.
In five to 10 years, a maintenance application will be needed, but it will be nowhere near the magnitude of the original application, he said.
"Over the course of the next year, tests will be taken to monitor the water quality," Shultz wrote. "Efforts will also be taken to reduce any future runoff into the pond to eliminate the need for more treatments."