Calm and clear weather made for perfect conditions for the environmental engineers who spread nearly 100,000 pounds of a clay-like mineral into the waters of Mill Pond in Water Mill this week, the start of an experiment to improve water quality in the pond.
Using satellite guidance, the crews from two environmental firms, SePro and Lycott Environmental, used a 24-foot-long pontoon boat outfitted with a long boom that blasted the liquefied granules of the mineral, known by the brand name Phoslock, into the pond’s waters as the boat followed a pre-drawn path around the pond. The application of the mineral, which is intended to remove high levels of phosphorous from the pond’s waters, began on Monday morning as a crowd of town officials and local residents looked on, and was expected to be completed on Thursday.
The results from the experiment likely will not be immediately apparent, since the soupy green algae blooms the experiment is targeting typically don’t appear until waters warm in summer.
Standing on the shore of Mill Pond on Monday as the application boat made its first pass across the pond, town officials touted the years of effort by residents and the Southampton Town Trustees to plan the experiment and bring it to fruition.
“I’d like to thank the Trustees for their perseverance,” Southampton Town Councilwoman Christine Scalera said, “especially Fred [Havemeyer], who was doggedly on top of this project.”
Town Trustee Fred Havemeyer and Water Mill resident Steve Abramson were applauded by many gathered at the pond Monday for having identified the use of Phoslock as the best hope for restoring water quality in the pond, degraded by the effects of high phosphorous and nitrogen levels, and having shepherded the town through the decision to fund the project, which will cost more than $450,000 over the next two years.
“This is going to treat the lake. It’s going to starve the algae, but it’s not going to affect the water column,” Mr. Havemeyer told onlookers on Monday. “Very soon, we’re going to have a healthy lake.”
The engineers conducting the application of Phoslock to the pond said that after the two major applications this spring and in the spring of 2014, they will conduct regular water testing in the pond to determine how quickly phosphorous levels rise from continued inputs through groundwater carrying the ill effects of decades of heavy farmland fertilizer and pesticide use, and residential septic leaching. They said there would likely be a need for future additional, though smaller, applications of Phoslock to tamp down phosphorous levels.
SePro representative Shaun Hyde said that the Phoslock application was approved by the State Department of Environmental Conservation and is certified for use in bodies of water that serve as drinking water resources. He added that it poses no threat to birds and fish in the pond.
“It goes out as a slurry, so there is nothing for fish or birds to ingest,” he said. “We sampled this lake, and all the components in Phoslock are already in this lake at levels that are not common in other lakes. We sampled from an eco-tox standpoint and also human health levels. When you can get an impact, it’s at much higher levels than we’ll ever be using in this lake. But that’s typical with too much exposure to anything.”
Phoslock is a mineral engineered by scientists working for the Australian government, specifically to help control algae blooms in water bodies, according to SePro. Phoslock has been used extensively in European and Australian reservoirs and ponds to combat algae blooms, but the Water Mill project will be one of the first in the United States. Phoslock is made from naturally occurring Bentonite clay, which makes up much of the substrate on the South Fork. The granules of clay have been modified to boost levels of lanthanum, a metallic chemical element that is found naturally in bentonite clay, to increase the amount of phosphorus that will bind to the granules.
The Trustees tested the chemical in a small portion of Mill Pond in the fall of 2011 and decided to move forward with the larger application based on the results.
In 2008, the die-off of a very large algae bloom suffocated thousands of fish in the pond, giving new urgency to years of pleas of pondfront residents for the Trustees to address the chronic water quality issues in the pond.