Toxic Algae

Lakes, reservoirs, rivers and streams are critical sources of drinking water for millions of Americans. They also provide recreational opportunities and wildlife habitat.

Now many of these water bodies are threatened by a growing phenomenon known as algae blooms, fueled largely by polluted runoff from farms and exacerbated by climate change. Algae blooms wreak havoc on ecosystems, and the cyanobacteria that make up these outbreaks sometimes produce poisonous byproducts called cyanotoxins. Ingestion of or even just exposure to these toxins has been associated with many human health issues, ranging from diarrhea to cancer, as well as with pet and wildlife deaths.

Currently, no government agency publicly tracks toxic algae outbreaks nationally. To fill this gap and help policymakers and consumers understand and quantify the impact of toxic algae blooms on drinking water, recreation, public health and the environment, EWG is monitoring and mapping all related news reports across the U.S. since 2010.

If you see algae that is bluish-green or looks like pea soup in a lake or other water body, contact the local health department to let them know and have it tested for toxins. You can also reach out to local media to try to get coverage of the issue.

Check out our map here.

View photos of algae blooms here.


Map of Algae Blooms Across the U.S.

Click on the below image to see an interactive map of where all algae blooms have occurred since 2010.

Location of algal blooms from 2010 to May 2019

Wednesday, May 16, 2018

In 2010, there were just three reports of toxic blooms in the U.S. In 2015, there were 15, including the largest to date in Lake Erie, although the bacteria did not get into Toledo’s drinking water. In 2016, there were 51, including a huge bloom in Florida that prompted the state to declare an emergency in four counties on the Atlantic Coast. Last year, 169 blooms were reported. And in March, Ohio Gov. John Kasich declared the open waters of western Lake Erie “impaired for recreation” – an unprecedented designation that under the federal Clean Water Act will require the development and enforcement of plans to reduce toxic blooms.

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Reports & Consumer Guides
Tuesday, May 15, 2018

In 2014, Toledo was the first U.S. city where a toxic algal bloom made tap water unsafe to drink. But it may not be last, says a new report by the Environmental Working Group.

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News Release
Tuesday, May 15, 2018

Across the U.S., a growing epidemic of toxic algal blooms is polluting lakes and other waterways, according to a new report by the Environmental Working Group.

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News Release
Thursday, September 8, 2016

From Florida beaches to Lake Erie to the California Delta, algal blooms threaten human health and aquatic ecosystems. Cyanobacteria, commonly known as blue-green algae, produce toxins that can make people sick and even kill pets.
 

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Key Issues:
AgMag
Article
Thursday, June 30, 2016

What comes to mind when you think of the Florida coast? Sandy beaches, sunshine, warm water and … toxic algal blooms? 

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Key Issues:
AgMag
Article
Friday, October 9, 2015

Ripped from the pages of an obscure science fiction novel, millions run screaming from the threat of a toxic algal bloom blanketing almost 650 miles of the Ohio River. Regrettably, this story isn’t made up. Officials in the Ohio River basin are scrambling to deal with poisonous slime that may compromise the safety of drinking water, suffocate aquatic life and halt recreational activity for much of the region.

 

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AgMag
Article

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