Long Island Water Risks

Long Island researchers say a dangerous warm-water bacterium and toxic algal blooms are now showing up in local bays, ponds and estuaries. (foxweather.com) The bacterium is *Vibrio vulnificus*, which can infect people through open wounds in brackish water, where salt and fresh water mix. Christopher Gobler of Stony Brook University said his team is finding it in most local water bodies, with the highest levels in the heat of summer. (cbsnews.com) Gobler said some of the Long Island sites where the bacterium was detected include Mecox Bay, Sagaponack Pond and Georgica Pond. Fox Weather, citing local reports on April 22, 2026, said many estuaries, harbors, bays, lakes and ponds failed 2025 water-quality standards. (foxweather.com) A harmful algal bloom is a fast-growing outbreak of algae or cyanobacteria that can release toxins or strip oxygen from water. Stony Brook said more than two dozen Long Island lakes and ponds had blue-green algal blooms in 2024, and more than 25 marine locations had harmful blooms as well. (dec.ny.gov) (news.stonybrook.edu) The same 2024 assessment found a record 36 dead zones, meaning areas where dissolved oxygen fell below three milligrams per liter, the New York State threshold for waters that support fish and shellfish. Stony Brook linked six fish-kill events on the south shore to oxygen levels below that standard. (news.stonybrook.edu) Gobler’s group has tied much of the decline to nitrogen washing in from land, especially wastewater from aging septic systems and cesspools. In an April 2025 Stony Brook summary, the university said groundwater nitrogen on Long Island had risen by more than 60% since the late 20th century. (news.stonybrook.edu) The public-health risk is not limited to swimmers. New York State’s shellfish monitoring program has issued temporary closures this month for Jockey Creek, Town Creek, Goose Creek and parts of Shinnecock Bay because mussels tested positive for saxitoxin, a marine toxin that can cause paralytic shellfish poisoning. (dec.ny.gov) (content.govdelivery.com) The bacteria threat is also newer here than the algae problem. Gobler told CBS New York that *Vibrio vulnificus*, once associated more with southern states, appeared in New York in 2023, when three people died on Long Island Sound. (cbsnews.com) Researchers and state agencies are also pointing to examples where cleanup changed the numbers. Gobler said western Long Island Sound’s dead zone shrank by 90% over two decades after sewage treatment plants cut nitrogen by 60%. (cbsnews.com) For beachgoers and boaters heading into summer 2026, the practical advice is concrete: avoid entering brackish water with an open wound, check shellfish closures before harvesting, and watch state and local harmful algal bloom alerts as New York’s 2026 monitoring season begins in May. (cbsnews.com) (dec.ny.gov)