A Summer of Discontent in Long Island's Coastal Waters

New 2017 Report Shows Excessive Nitrogen Continues to Fuel Hypoxia, Toxic Algae Blooms threatening Public Health and Water Quality

Patchogue, NY

Scientists at Stony Brook University have completed their assessment of water quality in Long Island’s estuaries in 2017 and the news is not good –the announcement was made today at a press conference at Fire Island National Seashore Visitor’s Center. During the months of May through August, every major bay and estuary across Long Island was afflicted by a toxic algae blooms or oxygen starved waters or both. Heavy loads of nitrogen from sewage and fertilizers have been cited as the ultimate cause of these disturbing events.

“It began with paralytic shellfish poisoning events in May and ended with a harmful rust tide that continues today across the east end Long Island,” said Dr. Christopher Gobler, Professor of Stony Brook University. “In between, the longest and most intense brown tide bloom in recorded history, toxic blue-green algae in 14 lakes across the Island, seaweeds on ocean beaches, oxygen depleted waters found at more than 20 locations from Hempstead to East Hampton. The confluence of all of these events in all these places across Long Island in a single season is a clear sign of things being amiss.”

The brown tide bloom in 2017 began in mid-May and continued into August and through that time covered waters from Freeport to Southampton. While only a few brown tides have been this extensive and extended, none have been as intense as the 2017 event as brown tide cell densities exceeded 2.3 million cells per milliliters in Great South Bay, a level never recorded by any entity on Long Island. As little as 50,000 cells per milliliters of brown tide can be harmful to shellfish, a level sustained for more than 10 weeks this summer.

Another disturbing occurrence was the widespread nature of dead zones across Long Island. Dead zones are regions of low or no oxygen and the NYS Department of Environmental Conservation mandates that marine waters should never go below three milligrams of dissolved oxygen per liter to allow fish to survive. Through the summer, the majority of sites sampled did not meet these criteria. “The data reveals that that many sites are not suitable habitats for sustaining fish and shellfish,” added Gobler.

Equally alarming was the large number of new water bodies with toxic blue-green algal blooms discovered in 2017. While several of the locations such as Long Island’s largest lake, Lake Ronkonkoma, have had chronic problems, some of the 15 sites with toxic blue-green algal blooms experienced these events for the first time. In 2016, Suffolk County had more lakes with blue-green algal blooms than any other of the 64 counties in New York State, a distinction that is likely to be repeated in 2017. Blue-green algae make toxins that can be harmful to humans and animals and were linked to dog illnesses in multiple years and a dog death in 2012.

And all of these events can be traced back to rising levels of nitrogen coming from land and entering Long Island’s surface waters. The largest sources of nitrogen are household sewage and fertilizers which are washed into groundwater that seeps in bays, harbors, and estuaries. Nitrogen stimulates toxic algal blooms that can, in turn, remove oxygen from bottom waters as they decay.

“Our water quality is degrading before our eyes,” said Adrienne Esposito, Executive Director, Citizens Campaign for the Environment. “Our bays are dying and the science clearly shows us why. Doing nothing is not an option. The problem will not fix itself. We need to rapidly move forward with advanced innovative septics, expansion of sewers, and creation of the Long Island Nitrogen Action Plan.”

The occurrence of these events such as brown tide, have led to the collapse of critical marine habitats such as seagrass, major fisheries on Long Island such as scallops and clams, and the coastal wetlands that help protect waterfront communities from the damaging impacts of storms. Groups such as The Nature Conservancy have been working for more than a decade to revive and restore these habitats and shellfish, but have been challenged by algal blooms such as those witnessed during the summer of 2017.

“The Nature Conservancy is grateful for the leadership Governor Cuomo and our Long Island legislative delegation, including Assemblyman Englebright and Senator Hannon, have provided as we work to address water quality on Long Island,” said Carl LoBue, NY Ocean Program Director with The Nature Conservancy. “It has gotten to the point that we have to watch News 12 each week to see where it is safe to swim or fish. Fortunately, our state leaders invested $2.5 billion for water quality in this year’s state budget, including a new septic rebate program. This funding, along with local funding and efforts such as the Long Island Nitrogen Action Plan and the permitting of new septic technologies will go a long way to make our waters clean again. We stand ready to continue our work with state and local officials and our partners to implement these important programs.”
"Although this year's research paints a bleak picture of the scale of Long Island's water quality crisis, recent investments in advanced sewage treatment projects and programs mark the beginning of measurable water quality action by local, county and New York State governments. These are critical first steps, but the data tell us there is far more to be done," stated Bob Deluca, President, Group for the East End.

“The quality of our local bodies of water is not only vital to the region’s important tourism industry, but is vital to the way of life that so many Long Islanders have grown accustomed to and have come to love. It is our hope that the Long Island Nitrogen Action Plan will play a critical role in reversing the trend of worsening algal blooms that has been observed in recent years,” stated Dick Amper, Executive Director, The Long Island Pine Barrens Society.

The report on the summer of 2017 was compiled by Dr. Christopher Gobler, Professor of Stony Brook University, whose lab groups has been monitoring and sampling Long Island’s waters on a weekly basis all summer. Data was also collected from the Long Island Sound Study which is funded by US Environmental Protection Agency. The data was reported weekly on News 12 as part of their weekly Water Quality Index.

The map generated by the report shows precisely where on Long Island various algal blooms and low oxygen zones developed during the summer of 2017. Events depicted include algal blooms caused by Alexandrium causing paralytic shellfish poisoning and shellfish bed closures, rust tides caused by the algae Cochlodinium, brown tides caused by Aureococcus, toxic blue green algae blooms commonly caused by Microcystis, and seaweed blooms caused by Ulva. The map also depicts hypoxic or low oxygen zones which are dangerous to marine life in Long Island Sound, Smithtown Bay, and more than 20 other locations across Long Island.

The LICWP pointed to the commitment by Governor Cuomo, Commissioner Seggos and the Long Island legislative delegation to this issue and noted that their investments will make measurable gains in water quality improvement. State, County and local leadership to advance water protection has provided new and unprecedented resources to address this issue including;
$2.5 billion allocated in the NY State budget for water quality, including funding for septic system rebates, sewer infrastructure upgrades and source water protection

  • $300 million in the Environmental Protection Fund
  • $5 million for the Long Island Nitrogen Action Plan.
  • The Governor established a new $10 million shellfish restoration effort for LI.
  • The US EPA is crafting a Long Island Sound Nitrogen Action Plan
  • Nassau County is advancing the consolidation of Long Beach STP to Bay Park and utilizing an existing ocean outfall pipe
  • By the end of the year Suffolk County will have approved 12 different waste water treatment technologies.
  • Suffolk County’s grant program to allow homeowners $10,000 to replace aging septics with new waste water treatment technologies.
  • The 5 East End Towns have established a reoccurring fund for water quality protection.
  • Town of East Hampton and Town of Southampton passed legislation requiring new construction and large scale reconstruction to use modernize waste water treatment technology

The study was supported by the Rauch Foundation through its funding of the Long Island Clean Water Partnership (LICWP), which the Foundation helped establish as a unique collaborative model advancing clean water action across the region.



The Nature Conservancy is a global conservation organization dedicated to conserving the lands and waters on which all life depends. Guided by science, we create innovative, on-the-ground solutions to our world's toughest challenges so that nature and people can thrive together. We are tackling climate change, conserving lands, waters and oceans at an unprecedented scale, providing food and water sustainably and helping make cities more sustainable. Working in 79 countries and territories, we use a collaborative approach that engages local communities, governments, the private sector, and other partners. To learn more, visit or follow @nature_press on Twitter.