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Nutrient Pollution and Algae Blooms

Many of Rockland County’s waterways are suffering from Nutrient Pollution, which is one of the nation’s most widespread and costly environmental and public health challenges (EPA). This occurs when excess nutrients, predominantly Nitrogen and Phosphorus, enter our waterways mostly from human activity where naturally-occurring algae gobble them up and multiply to high “bloom” levels. Algae blooms starve the water of oxygen (a condition known as ‘hypoxia’), causing fish and shellfish die-offs. [ See our Nutrient Pollution Fact Sheet ]  


Harmful algae blooms (HABs) occur when blue-green algae, found naturally in waterbodies, form toxins that are harmful to humans and animals. Multiple HABs have been confirmed in Rockland County

It's not easy to tell a HAB from non-toxic algae, and both can be present at one time. If you suspect you have seen one or have been in contact with one, please refer and report it to the NYSDEC Harmful Algae Bloom Notification Page. You may also refer to the NYSDEC’s HAB brochure or see the NYSDEC's 7-minute video on identifying HABs. 

In the Town of Clarkstown one of the main effects of nutrient pollution, particularly Phosphorus, is algae growth throughout the lake systems.

Many of our notable Estuaries are suffering from Nutrient Pollution. The Gulf of Mexico and the Chesapeake Bay are the final destination of multiple waterbodies that carry nutrients from agriculture runoff. Both suffer yearly Dead Zones [1] [2].


Nutrient Pollution has been extreme in the Long Island Sound. Efforts targeting stormwater pollution and wastewater treatment have reduced nutrient loadings in the Sound and in 2015 whale sightings were noted after a two-decade absence. The Billion Oyster Project aims to reduce nutrient pollution in New York harbors, as well as build natural storm barriers.  We must always be diligent about our pollutant-generating activities that reach waterways!

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Click on images for source.  Additional images courtesy of UnSplash, NYSDEC.


Jennifer Zunino-Smith
Environmental Resource Educator
(845) 429-7085 x125

Last updated November 3, 2022