VIDEO: Treatment of Mill Pond Nutrient Pollution Begins

The Southampton Town Trustees, who are in charge of the town's waters, as well as members of the Southampton Town Board and representatives of environmental services companies gathered at Mill Pond in Water Mill Monday for the start of a of the beleaguered water body.

Mill Pond is being given an application of Phoslock, a 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.

The trustees previously cordoned off a channel of Mill Pond last year to test Phoslock, and Trustee Fred Havemeyer said last month that, after the successful trial run, they are trying on the whole 87-acre pond. The four-day process is the first Phoslock application in New York State, he added.

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.

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