Shelter Island Generations Long Island’s smallest township is a microcosm of the region-wide water quality problem. © Red Vault Productions

Long Island Water Quality


Shelter Island

Generations Long Island’s smallest township is a microcosm of the region-wide water quality problem.

All That Land is Preserved Land

A key tool for protecting water quality is land preservation. Long Island's five east end towns, along with Suffolk County, New York State, the federal government, and The Nature Conservancy have already acquired and protected over 150,000 acres of local open space and farmland. These protected lands, (including the magnificent 2,039-acre Mashomack Preserve which comprises nearly a third of Shelter Island) offer critical wildlife habitat, places to recreate, spectacular views, and natural shorelines.

We Have Our Aquifer and That's It

Residents and businesses in Nassau and Suffolk Counties rely on underground aquifers for all fresh water needs. Shelter Island residents rely exclusively on the aquifer beneath Shelter Island where the deeper aquifers are too salty for drinking or irrigation. The shallow depth of the drinking water aquifer on Shelter Island makes Shelter Island's water supply exceptionally vulnerable to contamination from land use, cesspools and septic systems, and salt water intrusion from over-pumping. A decade ago Suffolk County generated a map showing high nitrate concentrations in well water across Shelter Island.

More than 150,000 acres of local open space and farmland have been protected on Long Island's East End.
East End Mashomack Preserve protects over 2,000 acres on Shelter Island and is part of the more than 150,000 acres of local open space and farmland that have been protected on Long Island’s East End.” © Red Vault


The fish die-off this spring — it's obviously from excess nitrogen, which is from people.

In Spring 2015, three separate fish die-offs occurred along the Peconic River killing an estimated 300,000 menhaden and other species. The cause was lack of dissolved oxygen in the water - a direct result of algae blooms, as confirmed by a multi-agency study released in February 2016. The algae blooms are fueled by nitrogen pollution, primarily from cesspools and septic systems, sewage, and fertilizer leaching into the waterways.

Algae blooms contribute to low oxygen in the water in two ways. First, unlike during the daylight when algae photosynthesize and make oxygen, at night algae respire and use oxygen. Second, dead and decaying algae settle to the bottom which feeds bacteria that uses up more oxygen. The result is that dissolved oxygen in nitrogen impacted bays and harbors drops at night, and under certain conditions also can be low in daylight.

The frequency and severity of such events can be alleviated by reducing the nitrogen pollution that is fueling the algae growth.

Fish dead due to nitrogen pollution
Long Island Fish Kill Fish dead due to nitrogen pollution © Red Vault Productions

Explore Local Stories About Water Quality

We're Oyster Farmers
An oyster farm with 1 million oysters can filter 50 million gallons of water per day, making them a critical piece in protecting Long Island's water quality from nitrogen pollution
Southwest Nassau County
Jim's Solution
A Freeport junkman Jim Ruocco has witnessed what happens when 50 million gallons per day of minimally treated sewage effluent are discharged into a poorly flushed estuary.
Answers & Solutions
As a fishermen and scientist, Carl LoBue ponders what our successors will think about the decisions we make today, and how those decisions will impact the island’s fishing future.
Shelter Island
See how Long Island’s smallest township is a microcosm of the region-wide water quality problem.
On Display
When the new Great South Bay inlet created by superstorm Sandy opened up, it formed an 8-mile undeveloped stretch of Fire Island called the Otis Pike High Dunes Wilderness Area.
It's Imperative
Mastic Beach
Mayor Maura Sperry talks about how water quality affects one of Long Island’s most flood-prone communities.
Something Lost
George Remmer, commercial fisherman, restaurant owner, and college professor, laments the changes he has seen around Great River, Grand Canal and Great South Bay.
Collapse of a Legacy
North Sea
Howard Pickerel has hand-built 600 boats in his backyard. Pickerel boats were at one time the backbone of Long Island’s shellfishing industry.
A New Perspective
Evelyn O'Doherty is a year-round stand-up paddleboard racer, paddler, surfer and yoga teacher who lives in East Hampton.
On Georgica Pond
Even Long Island’s most bucolic communities are not immune to the effects of nitrogen pollution.
A Chef's Connection
Forty years ago Bruce Bollman had a vision that Long Island’s North Fork would become a destination calling for gourmet artisanal eateries.