Most of Long Island has three aquifers underneath it. Orient has only one—the shallowest and thinnest. That means we don’t have a deeper backup source if our water becomes polluted or overused. Because it’s so close to the surface, it’s much more at risk from contamination.

Below is an image of the rest of Long Island’s water resources: nearest the surface is the thin “Upper Glacial” aquifer, underneath which is the much thicker Magothy Aquifer (up to 1,100 feet thick), and below that Lloyd Aquifer (up to 500 feet thick).

Orient, however, only has the thin “Upper Glacial” aquifer (85 feet thick at its thickest point in Orient).  In orient, the Magothy and Lloyd aquifers are filled with saltwater.  So Orient’s fresh water supply is very limited and fragile.

Yes—for now. To answer this question, the hydrologists at CDM Smith created a “water balance” for Orient (see chart below) and found that household, farm, and business use is only about 15% of supply.

A water balance calculates the total inflows and outflows in a water system.  Total outflows should always equal total inflows, plus any changes in storage. When outflows consistently exceed inflows, the aquifer (the storage) declines and can eventually collapse.

In Orient’s case, inflows (on the left in the chart above) are almost entirely from rain and snow (“Recharge from Precipitation”).

The largest outflow in Orient is groundwater flowing naturally underground out to the Sound and the bays (“Subsurface Discharge”).

Human use of freshwater in Orient (“Commercial”, “Agricultural”, and “Potable” pumpage) consumes only about 15% of the available supply.  Even with a higher assumption for agricultural pumpage (e.g. in drought year), total human use of freshwater is less than 25% of available supply.

According to the hydrologists at CDM Smith, this is healthy balance and not overtaxing to our aquifer.

The short answer is: “no”.  The amount of water in Orient’s aquifer has remained fairly steady over the past fifty years. 

How do we know this?   Fortunately, the US Geological Survey has maintained a monitoring well in Orient (just south of Main Road near the intersection with Narrow River Road) since 1958.  That monitoring well has kept track of the height of the water table.  The water table acts as a gauge of the volume of water in the aquifer–when an aquifer is overtaxed and more water is pulled from it than is being recharged by precipitation, the height of the water table will fall.

As you can see in the chart above, the water table in Orient has remained fairly steady over these sixty-three years, at 2 to 5 feet above sea level, with seasonal variation each year (lower in summer, when residential and agricultural pumping and evaporation are greatest, and higher in the winter).  This indicates a fairly constant volume of water in our aquifer.

(A sidenote: you may notice that in the years 1958 thought 1964 the water table seems lower.  It is.  There was a drought during these years that caused a slight decline in Orient’s water table.)

Some wells in Orient have issues with contamination from nitrates, chloride, fecal bacteria, and more recently PFAS.  

To assess the quality of Orient’s fresh water, in 2022 CDM Smith analyzed the results of all of the water tests conducted on private wells in Orient between 1997 and 2021 by the Suffolk County Department of Health Services. 

The pollutant that exceeded state standards (“Maximum Contaminant Level” or “MCL”) most frequently in Orient wells was nitrogen–18% of wells tested in Orient were over the 10mg/l MCL for nitrates.  As illustrated in the chart below, nitrate in the groundwater in Suffolk County primarily comes from on-site wastewater (i.e. septic systems) and also from fertilizer.

Other contaminants CDM Smith investigated were chlorides (over MCL in about 4% of wells tested in Orient), fecal indicator bacteria (over MCL in 16% of tests), and pesticides and herbicides.

In addition, in 2022-2023 nearly half of the private wells in Orient tested for PFAS (“forever chemicals”) were above the MCL.

In 2022-2023, Suffolk County Department of Health Services (SCDHS) testing found PFAS above legal limits in 93 of 194 private wells in Orient village.

SCDHS and NYS Department of Environmental Conservation identified the Orient Fire Department as the potential source of the PFAS contamination.  The NYSDEC installed and is maintaining filtration systems in affected households in Orient.  The Fire Department and NYSDEC are conducting further investigation to confirm the source and assess the need for remediation.

Saltwater intrusion happens when salty groundwater, which normally lies below the aquifer, is pulled up into the freshwater (called “upconing”–see diagram below). 

This can happen when the bottom of the well is placed too close to the saltwater interface, when too much water is pumped out too quickly (as in filling a pool with a garden hose), or when the saltwater interface moves upward toward a well (during a drought or as a result of sea level rise).

About 4% of wells tested in Orient 1997-2021 were over MCL for chloride-an indication of saltwater intrusion.  This often happens during the summer, when fresh water levels are lowest. 

4% is not so many, but as sea level continues to rise an increasing number of households in Orient will experience saltwater intrusion.

Sea level in Orient is projected to rise nearly four feet by 2100.  As sea level rises, the bottom of the aquifer—the saltwater interface—also rises (see chart below, which gives a projection for the thickness of Orient’s aquifer in 2100).  This will increase the number of households in Orient experiencing saltwater intrusion.

The most vulnerable wells will be those in shallow parts of the aquifer (see map below).

In addition, as sea levels rise, the top of the aquifer—the water table—will rise with it.  A higher water table can overwhelm septic systems, sending more contamination into our groundwater and surrounding water bodies.

Over the past thirty years, the bodies of water neighboring Orient—particularly the western reaches of the Peconic Estuary and western Long Island Sound—have suffered regularly from low levels of oxygen caused by high concentrations of nitrogen, leading to harmful algae blooms and fish kills.  These high levels of nitrogen have been traced back to septic systems, which leak nitrates into the aquifer and out into the bays, and to fertilizer.

Orient Harbor, however, has maintained healthy levels of oxygen.  As you can see in the chart below, over the course of 2024 the oxygen level in Orient Harbor did not fall below the “acute” standard (3mg/l) at any point, and did not average less than the “chronic” standard (4.8mg/l) on any full day. 

The relative health of Orient Harbor’s water is most likely due to low population density around the Harbor (i.e. fewer septic systems contributing nitrates to the bay) and to the twice-a-day flushing of the bay from the larger Gardiner’s Bay and the Atlantic beyond

This map shows the approximately 812 houses in Orient on white lots.  Some 249 additional houses could be built based on pending subdivision plans and current zoning of subdividable parcels.  This represents a potential 30% increase.

126 “vacant” buildable lots are shown in red. In yellow, 9 “oversized” lots with existing houses could be subdivided to add approximately 19 lots.

In purple are 15 subdividable “vacant” parcels.  They vary from 4 1/2 acres to 32 acres. The total yield on these is approximately 74 new house lots. Most have R-80 zoning, which means the yield is based on 80,000 square feet per lot (nominally 2 acres).  The town code requires that subdivisions over 7 acres be designed with the new lots clustered together.  With public water, these could possibly be smaller than the 40,000 sf. required by Suffolk County Department of Health Services for houses without public water.  There would be the same number of houses, but they could be smaller lots with smaller houses. Total yield would only change if the zoning were to change.

Four subdivisions (orange) in some phase of review by the Southold Planning Board have a total yield based on the current proposals of 32 new houses but would increase if the pending conservation subdivisions were to become standard subdivisions.

Additional increased development could occur if:

• Many Accessory Dwelling Units are built
• Zoning is changed
• Introduction of an Affordable or “Community” Housing Overlay District which can have higher density than the underlying zoning of a particular parcel with sanitary flow credits.

The opportunity for commercial development in Orient is limited to a handful of parcels with very little potential for increased intensity of use given the current zoning and stability of the Cross Sound Ferry.