Hudson River Suffers Worst Algal Bloom in 40 Years Amidst Warmer Waters and Sewer Overflow

Strategic Insights -

Roughly 60 miles of the Hudson River, spanning from Beacon to just north of Germantown, have been plagued by a thick layer of pea soup-colored scum composed of cyanobacteria, which is an uncommon occurrence in a river that typically flows in two directions and mixes with ocean water several times per day. The bloom, which scientists call the Hudson's worst outbreak in the last 40 years, is a direct result of warmer waters, drought, and sewer overflow. While recent cooler temperatures have helped dissipate the bacteria, experts predict that these blooms will worsen as the weather gets hotter and drier.

Key Takeaways:

  • The Hudson River has experienced its worst algal bloom in 40 years, affecting a 60-mile stretch from Beacon to just north of Germantown.
  • Warmer waters, drought, and sewer overflow have contributed to the bloom, which is typically found in stagnant waters such as ponds and lakes.
  • Scientists predict that these blooms will worsen as the weather gets hotter and drier, with warmer temperatures and droughts making it more likely for algal blooms to occur.
  • The region experienced its warmest September since 2018, with an average temperature of nearly 71 degrees Fahrenheit.
  • The city received only 8.7 inches of rain during the summer, making it the driest summer since 1999 and contributing to less robust flow on the river.
  • Sewage containing nitrogen and phosphorus entering the Hudson River is also contributing to the bloom.
  • The algal bloom has not affected drinking water in towns that depend on the Hudson River, as pollutants like phosphorus and nitrogen are filtered out before they hit faucets.
  • Physical contact, inhalation, and ingestion of cyanobacteria pose hazards to animals and humans, particularly children, with symptoms including minor skin irritation and gastroenteritis, as well as more severe outcomes.
  • Consuming contaminated fish is also dangerous, and the algal blooms can cause the sudden mass death of fish in the area.

Statistics:

  • The Hudson River is experiencing its worst algal bloom in 40 years, affecting a 60-mile stretch.
  • The region experienced its warmest September since 2018, with an average temperature of nearly 71 degrees Fahrenheit.
  • The city received only 8.7 inches of rain during the summer, making it the driest summer since 1999.
  • Cyanobacteria concentrations in the Hudson River are high, even for a tidally mixed river like the Hudson.
  • The initial monitoring data indicates low risks to public health, but the department advises people to avoid areas showing signs of algal bloom.
  • According to the U.S. Centers for Disease Control and Prevention, physical contact, inhalation, and ingestion of cyanobacteria is hazardous to animals and humans, with risks including minor symptoms, gastroenteritis, and more severe outcomes.

Sources:

  • Cary Institute: Stuart Findlay, senior scientist
  • Riverkeeper: Shannon Roback, science director
  • National Weather Service:
  • Federal drought monitor:
  • U.S. Centers for Disease Control and Prevention: