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.
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.Read More
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.Read More
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.”Read More
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.Read More
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.Read More
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.Read More
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.Read More
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.Read More
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.Read More
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.Read More
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.Read More
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.Read More
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.Read More
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.Read More
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.Read More