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.


News Reports of Algae Blooms Across the U.S., 2010 to Present

Click on the below image to see an interactive map of where news reports have been written about algae blooms since 2010.

Wednesday, October 14, 2020

The end of summer marks the unofficial end of the algae outbreak season. Warmer states like California and Florida see outbreaks fouling lakes, rivers and other bodies of water year-round, but for most of the country, outbreaks stop when the weather turns colder.

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Key Issues:
AgMag
Article
Wednesday, September 30, 2020

Either toxic algae or potentially dangerous fecal bacteria forced the closure of at least 116 U.S. beaches this spring and summer and triggered health warnings at 162 more, according to a new analysis by the Environmental Working Group.

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Reports & Consumer Guides
Wednesday, September 30, 2020

Toxic algae and bacteria forced the closure of at least 116 U.S. beaches and triggered health warnings at 162 more this spring and summer, according to an investigation by the Environmental Working Group.

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Key Issues:
News Release
Wednesday, September 2, 2020

If you’re headed for the lake or river this Labor Day weekend, be on the lookout for outbreaks of potentially toxic algae. Through the end of August, algae blooms have plagued 318 bodies of water across the U.S., with many more expected in September and beyond.

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Key Issues:
AgMag
Article
Wednesday, August 26, 2020

Communities across the United States have spent more than $1 billion since 2010 dealing with outbreaks of potentially toxic algae in lakes, rivers and drinking water supplies, according to a groundbreaking new analysis by the Environmental Working Group.

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Key Issues:
News Release
Wednesday, August 26, 2020

Communities across the United States have spent more than $1 billion since 2010 dealing with outbreaks of potentially toxic algae in lakes, rivers, bays and drinking water supplies, according to an analysis by the Environmental Working Group.

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Reports & Consumer Guides
Tuesday, July 28, 2020

As some COVID-19 shutdowns now stretch into their fifth month, and with record-setting temperatures blanketing the U.S., cooped-up Americans may be hankering for water-centric recreation. But those with pet dogs may want to leave them at home to protect them from the growing problem of toxic algae outbreaks – and to stay out of the water themselves.

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Key Issues:
AgMag
Article
Thursday, July 23, 2020

Toxic algae outbreaks – slimy, smelly blooms of microorganisms, triggered by polluted farm runoff into lakes and rivers – can cause nausea, vomiting and more serious, longer-term health impacts, such as liver failure and cancer, in people exposed through recreational contact or drinking water.

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News and Analysis
Article
Wednesday, July 1, 2020

Over the Fourth of July holiday, don’t act like the crowds recreating in Grand Lake St. Marys, Ohio. With area pools closed due to the pandemic, people are flocking to the lake to cool off, despite the state’s guidelines on social distancing and large gatherings.

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Key Issues:
News and Analysis
Article
Wednesday, June 10, 2020

With summer beginning and millions of Americans experiencing what feels like the thousandth week of quarantine, enjoying the outdoors is one of the few ways many of us can escape the claustrophobia and drudgery of the COVID-19 pandemic.

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Key Issues:
News and Analysis
Article
Monday, April 13, 2020

The Army Corps of Engineers just opened a huge flood management structure to relieve the swollen Mississippi River, which could cause a recurrence of a huge toxic algae bloom along the Gulf Coast, potentially affecting fisheries, recreation and ecosystems.

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News and Analysis
Article
Thursday, February 20, 2020

Studies of the health hazards of toxic algae blooms have focused largely on the danger of direct contact with contaminated water in lakes, rivers and the ocean. Now a new study shows that even airborne exposure to the bacteria from a toxic bloom could also pose a risk.

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AgMag
Article
Thursday, January 16, 2020

Florida health officials are warning of an unusually early outbreak of blue-green algae on the Caloosahatchee River, a popular tourist area on the state’s southwestern Gulf Coast.

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AgMag
Article
Monday, October 7, 2019

EWG has found 508 news reports about algae blooms in the country’s lakes, ponds and rivers so far this year – 18 percent more than the 429 we found in the same period last year.

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AgMag
Article
Thursday, August 29, 2019

A record-breaking number of potentially toxic algae blooms have plagued bodies of water across the country this summer. According to our map, which tracks news stories of algae blooms, as of August 27, 354 algae outbreaks have occurred in 41 states. That’s 65 more bloom stories than the 289 that had occurred by this time last year.

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AgMag
Article
Thursday, August 15, 2019

Last week, Melissa Martin and Denise Mintz took their dogs – Abby, Harpo and Lizzy – for a swim in a pond near their home in Wilmington, N.C. Within hours, the dogs grew sick and died, apparent victims of poisoning from toxic algae blooms.

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News and Analysis
Article
Thursday, August 15, 2019

Outbreaks of potentially toxic algae are fouling lakes, rivers and other bodies of water across the U.S. Nationally, news reports on algae outbreaks have been on the rise since 2010.

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Children's Health
Article
Thursday, August 8, 2019

Microcystins are poisonous toxins that can form in blooms of blue-green algae. In recent years, algae blooms – actually microscopic bacteria called cyanobacteria – have erupted in hundreds of lakes nationwide, putting at risk Americans whose drinking water comes from those lakes, or who swim, ski or fish in them. If ingested, microcystins can cause adverse health effects in people and animals, ranging from skin rashes to serious illness and even death.

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Reports & Consumer Guides
Thursday, August 8, 2019

In 2011, Sen. Jim Inhofe, R-Okla., fell “deathly sick” from a severe upper respiratory illness after swimming in a lake infected with toxic algae. Inhofe, a notorious science-denying patron of corporate polluters, laughed it off as “the environment strikes back.”

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AgMag
Article
Thursday, August 8, 2019

Federal and state tests have found dangerous toxins, common in outbreaks of blue-green algae, in hundreds of lakes, rivers and other bodies of water nationwide – yet authorities are doing little to notify and protect Americans, according to a new analysis and map from the Environmental Working Group.

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News Release

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