Plum Island is an approximately 840-acre island in Long Island Sound, just off Orient Point on the North Fork of Long Island. Although geographically part of Suffolk County, the island has long been under federal control and remains closed to the general public. Best known as the site of the Plum Island Animal Disease Center (PIADC), Plum Island is also notable for Fort Terry, Plum Island Light, and its important coastal wildlife habitat.

Geography & Location

Location: Off Orient Point at the eastern approach to Long Island Sound, Suffolk County, New York
Size: About 840 acres
Nearby Landmarks: Orient Point, Gardiners Island, Fishers Island, and the open waters leading toward Montauk Point
Access: Restricted; there is no general public ferry or casual visitor access

The island includes sandy shoreline, rocky stretches, salt marshes, meadows, and wooded areas, creating valuable habitat along a major migratory corridor on the Atlantic Flyway.

History

Federal Acquisition: The U.S. government acquired Plum Island at the end of the 19th century for military purposes.
Fort Terry: The island became home to Fort Terry, a coastal defense installation that served through the first half of the 20th century, including the World War I and World War II eras.
Wartime Role: During World War II, military activity on and around the island supported harbor defense and anti-submarine operations in the surrounding waters.
Animal Disease Research: In 1954, the U.S. Department of Agriculture opened the Plum Island Animal Disease Center to study serious livestock diseases. After the creation of the Department of Homeland Security in 2003, oversight of the site became shared at the federal level.
Transition to Kansas: Federal biocontainment and animal disease research functions have been shifting to the National Bio and Agro-Defense Facility (NBAF) in Manhattan, Kansas. The pace of the transition and remaining activities on Plum Island may continue to change.

Ecology & Wildlife

Plum Island is widely regarded as an important conservation site. Its habitats include:

Tidal flats and salt marshes
Sand dunes and beaches
Meadows and maritime woodland

Notable wildlife includes:

Harbor and gray seals that seasonally haul out along the shoreline
Migratory birds using the island as a stopover along the Atlantic Flyway
Rare and protected shorebirds associated with undeveloped coastal habitat

Because of its relatively undeveloped landscape and strategic location, environmental advocates have long argued that Plum Island should receive lasting conservation protection once federal operations fully wind down.

Structures on the Island

While there is no private residential community on Plum Island, the island still contains several distinct groups of buildings and infrastructure:

Military remnants: Fort Terry-era batteries, barracks, and support structures survive in varying states of preservation.
Research facilities: The PIADC complex includes laboratories, containment buildings, and security infrastructure tied to the island’s long federal research role.
Staff housing and service buildings: Government-owned cottages, dormitory-style quarters, and utility buildings were constructed for employees and operational support.
Harbor and utilities: Docks, warehouses, maintenance structures, and power-related facilities helped the island function as a largely self-contained site.

Some structures are still maintained for federal purposes, while others are disused or deteriorated, adding to Plum Island’s unusual and often mysterious reputation.

Historic Lighthouse

On the western tip of the island stands Plum Island Light, a granite lighthouse completed in 1869 to guide vessels through the busy waters near the entrance to Long Island Sound. With its attached keeper’s quarters, the station played an important role in regional navigation before modern electronic systems became standard.

The lighthouse was deactivated in 1978, but it remains one of the island’s best-known landmarks. It was listed on the National Register of Historic Places in 2011 and continues to symbolize Plum Island’s maritime past. The site is not open for routine public visitation, so most people see it only from the water or from a distance on clear days.

Future of Plum Island

Plum Island’s future has been the subject of years of debate. A 2008 federal law set the island on a path toward sale, but Congress later reversed that direction in 2020, effectively blocking commercial disposal and opening the door to conservation-focused alternatives. Local reporting on possible Suffolk County stewardship reflects one of several ideas that have been discussed as federal use changes.

Preservation advocates have proposed a future that emphasizes habitat protection, historic interpretation, and carefully managed public access. Environmental review, site cleanup, long-term ownership, and operating costs remain central issues, so final plans may continue to evolve.

Controversies & Conspiracy Theories

Because Plum Island has been closed and highly regulated for decades, it has generated a long-running mix of folklore, rumor, and genuine public scrutiny:

Lyme disease rumors: Claims that Lyme disease originated at the lab are not supported by the scientific record; the disease ecology predates PIADC.
The “Montauk Monster” story: A strange carcass that washed up in Montauk in 2008 sparked rumors of a Plum Island connection. Most explanations pointed to an ordinary animal carcass in an advanced state of decomposition.
Cold War speculation: The island’s secrecy and security led to persistent rumors about biological weapons work, but those claims have not been substantiated.
Documented oversight and safety concerns: Like other high-security research facilities, Plum Island has been subject to inspections, incident reporting, and periodic public concern over safety and environmental management.

Public Access

Plum Island is not open for general visitation. Access is limited to authorized personnel, and there is no public ferry or routine landing program for tourists. Travelers interested in the island usually experience it from afar, including views from Orient Point and nearby waters.

If public access is ever introduced in the future, it would likely be limited, guided, and subject to permits, seasonal schedules, and environmental protections. Check ahead before planning any trip based on possible future access.

Potential guided tours focused on ecology and history
Protected wildlife areas managed for habitat and limited viewing
Historic interpretation of Fort Terry and Plum Island Light

Quick Snapshot

Feature	Details
Location	Long Island Sound, off Orient Point in Suffolk County, NY
Size	About 840 acres
Status	Federal property; closed to the general public
Facility	Plum Island Animal Disease Center (opened 1954)
Future	Research transition to Kansas has been underway; long-term stewardship and conservation planning remain under discussion
Ecology	Marshes, beaches, meadows, and woodland supporting seals, migratory birds, and sensitive coastal species
Structures	Fort Terry remnants, lab complex, staff housing, docks, and utility buildings

Did You Know?

Plum Island once housed Fort Terry, a U.S. Army coastal defense installation.
Although it sits close to the tip of Long Island, the island is not open for casual public landings.
Seal sightings around the island are one reason Plum Island is often discussed as a future conservation preserve.
Its long-closed status has made it one of the most talked-about and least-visited places in Long Island lore.

Plum Island, New York