Potential Impacts of the
Sewage Treatment Plant 

on the Hither Woods aquifer

One of the reasons the land at Hither Woods was preserved in the first place was the necessity of safeguarding the freshwater aquifer which underlies this property.  Much of Montauk’s drinking water supply comes from Hither Woods.  There are two important public water wellheads maintained by the Suffolk County Water Authority within 1,500 to 2,000 feet of the Town’s proposed STP site.  While the Town and its engineers maintain that the treated wastewater emanating from the STP will have nitrogen levels low enough for that water to be drinkable, we are all aware that sewage contains many more contaminants than just nitrogen.  Plus, accidents do - and will - happen.  If untreated waste must ever be discharged from the Hither Woods STP, there is only one place for it to go: down into the freshwater aquifer.

When fully built out the sewage treatment plant, and associated land, are said to be capable of discharging a maximum of 550,000 gallons of sewage effluent per day.  According to the Town’s consulting engineers this is only slightly more than the maximum sewage being generated today - 530,000 gallons per day - by the four areas of Montauk which the Town eventually hopes to serve with its sewage plant.  The Town’s Natural Resources Department has stated that the sewage effluent from the plant will filter down to the aquifer on the north side of the “groundwater divide” under Hither Woods.  If true, this would mean the sewage plant’s wastewater would move towards Fort Pond Bay, rather than towards nearby public and private drinking water wells.

Unfortunately, even if the Department is correct about the location of the groundwater divide, in Hither Woods that divide is very modest.  The highest elevation of the groundwater table in Hither Woods is only five feet above sea level.  The Town’s STP will be pouring sewage effluent into the groundwater at a rate more than 25 times the normal recharge rate caused by natural precipitation (rainwater and snowmelt) on Eastern Long Island.  Such a concentrated amount of effluent could easily create a “bubble” atop the groundwater table, from which groundwater might then flow in all directions.

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