Nissequogue River Named Among Most ‘Endangered’ As Suffolk Pushes To Rebuild Dam: Report

SMITHTOWN, NY — The Nissequogue River has been named one of the most endangered rivers in the country, according to an American Rivers report, as Suffolk County plans to rebuild a dam that was breached during a 2024 storm.

The designation comes from American Rivers’ 2026 “America’s Most Endangered Rivers” report, a nationally recognized annual list highlighting waterways facing urgent threats and key public policy decisions.

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The Nissequogue River ranked seventh nationwide, with the proposed rebuilding of the Stump Pond Dam cited as the central concern.

The river, which flows from Smithtown to Long Island Sound, is designated as a “Scenic and Recreational River” by New York State and supports a wide range of wildlife, including native brook trout and migratory birds, the report said.

The debate stems from a major turning point in August 2024, when the Stump Pond Dam in Blydenburgh County Park failed during a powerful storm. The breach drained a 118-acre pond and transformed the area into more than two miles of free-flowing stream, reconnecting the river to its natural floodplain.

The report says the river has rapidly recovered since then.

More than 120 species have been documented in the restored area, native vegetation has returned, and water temperatures have cooled — improving conditions for fish and wildlife. The floodplain now also helps absorb stormwater, reducing flooding risks, according to the report.

“Rebuilding the dam would reverse recent gains for the river and communities by disrupting fish passage, degrading water quality, trapping sediment, warming the river, eliminating valuable floodplain, and reducing the floodplain’s capacity to manage stormwater," the report said.

Suffolk County officials said the dam’s loss has had negative consequences and are moving forward with plans to rebuild it.

County Executive Ed Romaine said the proposal has already advanced through the Council on Environmental Quality and is expected to head to the Suffolk County Legislature for approval.

In March, the Suffolk County Legislature voted that the project would not require a full environmental impact statement, despite the New York State Department of Environmental Conservation recommending a comprehensive review.

In a statement in February, Romaine said community feedback strongly supported restoring the dam and Stump Pond, which has served as a recreational hub for generations.

“The residents of the surrounding communities miss the recreational opportunities once afforded to them by the pond,” Romaine said, pointing to activities such as fishing, boating, hiking and horseback riding.

Romaine also said the dam previously played a role in flood control and that its absence has left nearby roads, parks, and private properties more vulnerable.

“The dam served as flood control for the area downstream,” he said.

Romaine said engineers have incorporated environmental considerations into the design, including plans for a fish ladder to allow species to move through the system.

The report said county and state officials should conduct a comprehensive environmental review and consider alternatives, including maintaining the river in its current free-flowing state.

The proposal, expected to cost more than $10 million, according to the report, will head into a critical phase, with the county still required to secure multiple state permits before construction can begin.