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

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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Key Issues:
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
Tuesday, July 2, 2019

Over the Fourth of July holiday, many of us love to beat the heat in a favorite lake, pond or river. But this year, vacationers from coast to coast will have to look out for a potentially record-breaking number of algae blooms.

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AgMag
Article
Thursday, June 6, 2019

Toxic algae blooms are a growing epidemic, polluting lakes and other waterways across the U.S., as a 2018 EWG report revealed. They can occur any time, but they thrive when water is warmer, usually from May through October.   

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Key Issues:
News and Analysis
Article
Tuesday, May 28, 2019

With peak toxic algae bloom season underway, the Environmental Working Group is releasing an updated map of all algae outbreaks reported in the U.S. since 2010. In coming months, the map will be updated weekly, providing comprehensive tracking of this growing nationwide hazard.

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News Release
Wednesday, April 24, 2019

Private wells across Iowa are contaminated with unsafe levels of two agricultural contaminants, according to an investigation by the Environmental Working Group and the Iowa Environmental Council.

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Key Issues:
News Release
Tuesday, April 9, 2019

Across America, outbreaks of toxic algae, triggered by polluted farm runoff, are increasing in frequency and severity, fouling drinking water with dangerous toxins. In 2014, an algae outbreak in Lake Erie contaminated the tap water for 500,000 people in and around Toledo, Ohio, rendering it unsafe to drink for three days. 

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Key Issues:
AgMag
Article
Tuesday, April 9, 2019

Unregulated animal factory farms are funneling nutrient-rich pollution into Lake Erie, feeding an enormous toxic algae bloom each summer, according to a new investigation by the Environmental Working Group and the Environmental Law & Policy Center.

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News Release
Monday, April 8, 2019

The Maumee River, overloaded with fertilizer and manure, is the single largest source of the phosphorus that triggers blooms of toxic algae in Lake Erie. Over half of the manure in the Maumee River watershed comes from an exploding number of unregulated factory farms, a new EWG and Environmental Law & Policy Center investigation reveals.

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Key Issues:
Reports & Consumer Guides
Wednesday, April 3, 2019

Outbreaks of toxic algae in U.S. waterways usually happen in warmer months. But in a sign that the problem is growing worse, algae blooms were reported in December in Michigan and Washington state, with another reported in Florida during the first days of spring.

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News and Analysis
Article
Tuesday, October 9, 2018

Outbreaks of potentially toxic algae in U.S. lakes, rivers and other waterways rose by an additional 40 percent this year compared to 2017, according to EWG’s tracking of news reports. 

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Key Issues:
AgMag
Article
Tuesday, September 18, 2018

This summer, EWG is tracking outbreaks of potentially toxic algae across the U.S. We have been startled to find that these outbreaks are erupting everywhere: from the East Coast to the West Coast, from the Great Lakes to the Gulf of Mexico.

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News and Analysis
Article
Friday, September 14, 2018

Outbreaks of potentially toxic algae in U.S. lakes, rivers, streams and even the Gulf of Mexico continue to rise sharply this summer, according to EWG’s ongoing tracking of algae outbreaks.

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Key Issues:
AgMag
Article
Friday, August 31, 2018

An unprecedented environmental catastrophe is striking Florida’s storied beaches, lakes and rivers this summer. Outbreaks of three separate strains of harmful algae are killing fish and other marine animals, threatening public health and devastating recreation and tourism.

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AgMag
Article
Friday, August 10, 2018

Outbreaks of potentially toxic algae are rising sharply this summer in lakes, rivers and streams in the U.S., according to EWG’s ongoing tracking of algae outbreaks.

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Key Issues:
AgMag
Article

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