Helping Communities and Water Utilities Address Harmful Algal Blooms

By Darren Lytle, Heath Mash, and Nick Dugan

Satellite image of west end of Lake Erie showing algal bloom.

Algal bloom in the west end of Lake Erie, August 3, 2014. Image courtesy of NASA Earth Observatory.

Toxins from harmful algal and cyanobacterial blooms are increasingly contaminating many of our nation’s source waters. We saw this just recently in Toledo, Ohio where toxins, most likely microcystins, made their way through the water treatment facility leaving many people without drinking water.

Many of the drinking water treatment facilities in the Great Lakes region were built before World War II and were designed to filter out particles of a certain size. As a result, removing the much smaller cyanobacterial toxins, such as microcystins, at these facilities can be difficult and expensive. Our research is helping communities confront this challenge.

Close up of hand filling a glass with tap water.

EPA researchers are helping to protect drinking water sources.

For example, recognizing the potential health and economic consequences of disruptions to municipal water supplies, we have partnered with Ohio EPA and the U.S. Geological Survey to conduct studies aimed at helping water treatment facilities cope with water quality changes in their water sources, and to optimize treatment to reduce risks associated with harmful algal blooms, also known for the acronym “HABs.”

Preliminary surveys of full-scale treatment facilities have shown that the size of the contaminant is key to the problems it can cause. Cyanobacteria cells are large enough for existing treatment facilities to remove by filters and other methods, as long as the cells remain intact. However, toxins leaking out of damaged or dying cyanobacteria cells can be difficult for existing facilities to treat without expensive additional actions or modifications.

To address this, we are looking for ways to improve the performance of existing drinking water treatment facility operations. Our researchers are looking at how to modify certain treatment operations such as where in the process treatment chemicals are applied, the types and concentrations of chemicals used for treatment and the pH levels at which the processes are operated. We are also conducting research on ways to improve sampling and analysis to more effectively monitor and control cyanobacteria and their toxins, including microcystins.

Harmful algal blooms aren’t just a major concern for drinking water. Fish, birds, and other animals can come in contact with or ingest these toxins, and suffer adverse effects. There have even been incidences of pet and livestock fatalities from drinking water contaminated with algal toxins.

Blooms can also affect recreational activities. For example, people swimming, waterskiing, or fishing in contaminated water can be exposed to algal toxins.

Some of our colleagues are working to better define the environmental factors controlling the development, persistence, and toxin production related to harmful algal blooms. Collaborative research efforts are focusing on controlling nutrient runoff, remote sensing and monitoring of such blooms, as well as developing early warning systems that would alert recreationists and drinking water treatment plant operators alike to their presence and the potential of toxin formation, to help eliminate exposure risk. Other researchers are exploring the human health effects related to microcystin exposures, with an eye toward developing a health advisory in the near future.

Our goal is to develop tools and methods that communities can use to manage potential impacts of harmful algal blooms. We want to ensure our water is clean for generations to come and protect the environment and the health of people, pets, and livestock across the country.

Learn more about EPA’s research on Harmful Algal Blooms and Cyanobacteria.

For more information on harmful algal blooms and our research, please share your questions in the Comment section below, or contact us directly at

About the Authors

Darren Lytle is an environmental engineer who focuses his research on drinking water contaminants and treatment technologies. He investigates corrosion control and water quality; lead and copper corrosion control; and filtration with an emphasis on removal of microbial pathogens.

Heath Mash is a chemist who studies the efficacy of hormone-like contaminant removal during water treatment, the occurrence and treatability of harmful algal bloom toxins, and identification of disinfection byproducts from hormones and algal bloom toxins material during treatment.

Nick Dugan is an environmental engineer currently focused on bench-scale trials evaluating the impact of common drinking water treatment oxidants on intact, toxin-producing cyanobacterial cells over a range of water quality conditions.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

EPA Science In Action: Keeping an Eye on Harmful Algal Blooms

By Cindy Sonich-Mullin

A half million people living in and around Toledo, Ohio recently experienced a weekend without tap water. A “harmful algal bloom” of cyanobacteria in Lake Erie, Toledo’s water source, produced unsafe levels of the toxin microcystin. The toxin is known to cause abdominal pain, nausea, vomiting, and at high exposure levels, liver damage.

A water advisory was issued alerting residents to avoid all contact with Toledo drinking water.

At the first sign of trouble, colleagues at the Ohio Environmental Protection Agency contacted my laboratory to provide technical assistance and water sample analysis to support the City of Toledo’s drinking water utility.

We were a natural choice to help out. Not only is EPA’s Cincinnati-based laboratory facility relatively close geographically, but our scientific staff includes a team of leading experts with analytical capabilities in drinking water treatment and cyanobacterial toxins.

Throughout the weekend, we performed tests and conducted sensitive analyses to help identify the optimal approach for controlling the toxins in Toledo’s water plant and distribution system. We shared our test results with our partners from Ohio EPA, who interpreted them along with their own results and others from the City of Toledo.

We were all greatly relieved the morning of August 6th, when the City of Toledo determined that they could lift the water advisory.

At the time, Ohio EPA Director Craig Butler released the following statement: “After exhaustive testing, analysis and discussions between Toledo water officials, the U.S. EPA and the Ohio EPA, we support the city’s decision to lift its drinking water advisory. Throughout the difficulty of the past few days everyone involved has demonstrated the utmost professionalism and commitment to solving this problem. The mayor and his team, U.S. EPA and the other scientific and academic leaders who lent us their expertise worked in a constructive way to turn the water back on for the people of Toledo.”

While many weekend plans were cancelled due to the crisis in Toledo, we were honored to be called on to help our sister city to the north. As scientists, it is gratifying to use our expertise and the tools we develop to provide solutions to communities. Of course, what would be even better than lending our expertise and rapid response and analysis capabilities would be to help prevent harmful algal blooms from threatening drinking water supplies in the first place. And that is just what we are doing. In fact, we’ve shared some of our harmful algal bloom research recently here on our blog. Below are some recent posts with more information on that work.

As the above blogs exemplify, EPA researchers are working hard to better understand the dynamics of harmful algal blooms. EPA is also working with other agencies to accelerate the development and deployment of affordable sensors that will help predict future algal blooms. This means we will be even better poised to work with cities like Toledo and other local communities to better protect precious drinking water supplies. Keep an eye here on “It All Starts with Science” to see future posts about that work, and more.

About the Author: Cindy Sonich-Mullin is the Director of EPA’s National Risk Management Research Laboratory in Cincinnati, Ohio. She has over 30 years of experience in EPA, leading research and response efforts on a wide variety of environmental issues.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

Monitoring Harmful Algal Blooms? There’s an App for That!

By Annie Zwerneman

Algal bloom covers a lake.

Algal bloom covers a lake.

I was recently on my favorite hiking trail, which passes by a beautiful lake. But this time hiking past it, I noticed a strange, dark scum creeping along the shoreline of the water. I learned later that this scum was actually an algal bloom: a population of algae increasing quickly over a short period of time.

Some algal blooms are merely an eyesore, but others fall into a more serious category called “harmful algal blooms” (HABs): algae and cyanobacteria (formerly known as blue-green algae) that remove oxygen from the water, crowding their way along the surface and producing toxins that are harmful to animals. The toxins that HABs produce can affect peoples’ health, too.

EPA has been working to monitor HABs, including taking water samples to see where and how algal blooms may affect you. Unfortunately, taking such water samples is time-intensive, so EPA has been working alongside scientists at the National Oceanic and Atmospheric Administration (NOAA), National Aeronautics and Space Administration (NASA), and the United States Geological Survey (USGS) to find new ways to monitor the quality of inland water bodies, such as lakes and reservoirs. EPA hopes to monitor estuaries and coastal waters in the future as well.

A new Android app is being developed that displays imagery of cyanobacterial cell counts in freshwater systems, which can indicate the presence of HABs. Expected to be in beta testing this fall, the app will provide information necessary for locating and monitoring HABs. It’s primarily aimed toward stakeholders like health departments and municipalities (such as water treatment plants).

The app will display data from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) satellite. In the near future, EPA researchers hope to incorporate the European Space Agency’s Sentinel-3 and potentially the Landsat-8 satellite as well. They will work with their NOAA, USGS, and NASA partners to pull all these capabilities together once the app is ready for public use.

The way the app will work is a bit like the weather station. At the beginning of each week, the cell count will be updated based on the satellite information gathered the previous week. There may even be a prediction of the cell count for the upcoming week available. For example, you can get a cell count in Lake Erie for the current week, and then get a prediction of what the cell count may be next week.

Thanks to the collaborative effort of multiple federal agencies, those looking for information about freshwater quality and HABs won’t have to look far: there will be an app for that!

About the Author: Annie Zwerneman is a 2014 summer intern working for the EPA’s Office of Research and Development.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

Modeling Cyanobacteria Ecology to Keep Harmful Algal Blooms at Bay

By: Betty Kreakie, Jeff Hollister, and Bryan Milstead

Sign on beach warning of harmful algal bloom

U.S. Geological Survey/photo by Dr. Jennifer L. Graham

Despite a lengthy history of research on cyanobacteria, many important questions about this diverse group of aquatic, photosynthetic “blue-green algae” remain unanswered.  For example, how can we more accurately predict cyanobacteria blooms in freshwater systems?  Which lakes have elevated risks for such blooms?  And what characteristics mark areas with high risks for cyanobacteria blooms?

These are important questions, and our ecological modeling work is moving us closer to finding some answers.

The gold standard for understanding cyanobacteria in lakes is direct measurements of certain water quality variables, such as levels of nutrients, chlorophyll a, and pigments.  This of course requires the ability to take on site (“in situ”) samples, something that is not possible to do for every lake in the country.  Our modeling work is focused on predicting cyanobacterial bloom risk for lakes that have not been directly sampled.

We are using remote sensing and geographic information systems (GIS) data to model bloom risk for all lakes in the continental United States.  The work is also starting to shed light on some of the landscape factors that may contribute to elevated predicted bloom risk.  For example, we know that different regions have different predictive risk.   We are also learning about how lake depth and volume, as well as the surrounding land use impact cyanobacteria abundance.

In addition to our national modeling efforts, we are collaborating with others on smaller scale and more focused studies at regional and local scales.  First, we are partnering with other EPA researchers to develop time-series models using data gathered frequently and over a long time by the U.S. Army Corp of Engineers.  By using these data, we expect to tease apart information about annual timing and the intensity of blooms.  We can also explore aspects of seasonal variability and frequency. Lastly, we are starting to explore ways to use approximately 25 years of data collected by Rhode Island citizen science as part of the University of Rhode Island’s Watershed Watch program.  We hope to mine these data and uncover indicators of harmful algal bloom events.

With all this work, we and our partners are adding new chapters to the long history of cyanobacteria research in ways we hope will help communities better predict, reduce, and respond to harmful blooms.

About the Authors: EPA ecologists Betty Kreakie, Jeff Hollister, and Bryan Milstead are looking for ways to decrease the negative impacts of cyanobacteria and harmful algal blooms on human health and the environment.

NOTE: Join Betty Kreakie, Jeff Hollister, and Bryan Milstead for a Twitter chat today (June 26) at 2:00pm (eastern time zone) using the hashtag #greenwater. Please follow us @EPAresearch.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

Open Science and Cyanobacterial Research at EPA

By: Jeff Hollister, Betty Kreakie, and Bryan Milstead

Green, algal-filled pond

Algal bloom containing cyanobacteria.

It wasn’t long ago that science always occurred along a well-worn path. Observations led to hypotheses; hypotheses led to data collection; data led to analyses; and analyses led to publications. And along this path, data, hypotheses, and analyses were held close and, more often than not, the only public-facing view of the research was the final publication.

Science has come a long way with this model.  However, it was conceived when print was the main media and most scientific questions could be investigated by few scientists over a short period of time.

Then came computers. Then came the internet.

Just like in every other aspect of modern life, these advances are greatly impacting science. It has changed who conducts our science, how we share it, and how others interact with scientific information. All of these changes are playing out through the increasing openness of all parts of the scientific process.

This broad area has been defined as having several components. These components suggest that “open science”:

  • is transparent (and, of course, open)
  • includes all parts of research (data, code, etc.)
  • allows others to repeat the work
  • should be posted on an open and accessible website (while protecting Personally Identifiable Information, etc.)
  • occurs along a gradient (i.e. not just a binary open vs. not open)

At EPA, we are learning how to make our research on cyanobacteria and human health (for more info join our webinar) meet those criteria.  We are implementing open science in three ways: (1) making our work available via open access publishing; (2) providing access to the code used in our analysis; and (3) making our data openly available.

Several members of our research group have embraced open access options for publishing their research. For instance, our colleague Elizabeth Hilborn and her co-authors published results of their study—examining a group of dialysis patients following exposure to the cyanobacteria toxin microcystin—in one of the pioneering open access journals, PLoS ONE. Also in PLoS ONE, EPA scientist Bryan Milstead and his collaborators published a modeling method to combine the U.S. Geological Survey’s SPARROW model (a modeling tool for interpreting regional water-quality monitoring data), lake depth, lake volume, and EPA National Lakes Assessment data to estimate nutrient concentrations.

As our work progresses, we will continue to choose open access journals. In our experience, this has allowed our research to reach a larger audience and we can more easily track the impact through readership levels using available tools such as PLoS Article Level Metrics.

We are also sharing our data. Currently, this is accomplished through supplements added to publications and through sites such as the EPA’s Environmental Dataset Gateway. We plan to expand these efforts via data publications, version-controlled repositories, and through the development of Application Programming Interfaces (APIs) that provide access to data for developers and other scientists.

The goal of these efforts, and more (stay tuned for a future post on how coding fits in to open science), is to increase the reproducibility of our work (but challenges remain), reach broader audiences, and eventually have a greater impact on our understanding and management of harmful algal blooms.

About the Authors: EPA ecologists Jeff Hollister, Betty Kreakie and Bryan Milstead study greenwater for a living. If you have questions for them, join the webinar on June 25th or follow the twitter chat on June 26th using #greenwater.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

When Green Goes Bad

Flyer banner for "When Green Goes Bad" webinar

By Lahne Mattas-Curry

When you think about the environment, what color comes to mind? Green, right? Because in everything we know in the environment “Green is Good.”

And while that is very often true, in the case of lakes and ponds that suddenly go green, it is most likely the result of an algae bloom, which, increasingly, contain many harmful cyanobacteria.  Also known as “blue-green algae,” some species of these tiny, photosynthetic aquatic organisms produce toxins. The impacts of these harmful algal blooms are widespread and often not good. Not good at all.

From acute adverse human health impacts such as respiratory and gastrointestinal problems (yuck) to known deaths of animals (keep the family dog out of green water, please!!), blooms like these are becoming a more frequent occurrence and are having greater impacts.

To better understand how algal blooms impact human health, identify the toxicity of cyanobacteria, predict the probability of bloom occurrences, and share this information broadly, our researchers have been working on a research project focused this topic since 2012.

The researchers involved in the project will be sharing what they have learned during a webinar on Wednesday, June 25 from 12:00 to 1:00pm as part of EPA’s Water Research Webinar Series.

We hope you will join them to hear an overview of the breadth of their algae bloom research, and learn details about ecological modeling they conducted on cyanobacterial blooms in U.S. lakes. They will explain how they embraced the concept of “Open Science”—the movement to make scientific research and data accessible to the public.

And if that’s not enough, they will also be available for a twitter chat on June 26 from 2:00pm to 3:00pm. You can submit questions now by using #greenwater or you can wait until the day of the chat. Please follow us @EPAresearch.

To register for the webinar, please send an email to with your name, title, organization and contact information.

Meet our Scientists

Jeff Hollister, Ph.D.
EPA research ecologist Jeff Hollister received his Ph.D. in Environmental Science from the University of Rhode Island. His past experience is in applications of geospatial technologies to environmental research and broad-scale environmental monitoring, modeling, and assessment. His current research focuses on how nutrients drive the risk of cyanobacterial blooms in lakes and ponds.

Betty Kreakie, Ph.D.
EPA research ecologist Betty Kreakie earned her Ph.D. in integrative biology from the University of Texas. Her work focuses on the development of spatially-explicit landscape level models that predict how biological populations and communities will respond to human-caused influences, such as nutrient and contaminant pollution, climate change, and habitat conversion.

Bryan Milstead, Ph.D.
EPA post-doctoral research ecologist Bryan Milstead received his Ph.D. from Northern Illinois University for work on small mammal population dynamics in Chile. Before coming to EPA, he worked for the U.S. National Park Service and for the Charles Darwin Foundation for the Galapagos Islands. His current work focuses on understanding how nutrient over-enrichment affects the aesthetic quality and risk of cyanobacteria blooms in lakes.

About the Author: Lahne Mattas-Curry communicates the many cool things happening in water science for EPA and hates #greenwater. She urges everyone to think twice about what fertilizers they use on their lawn and encourages pet owners to “pick up the poop” to reduce nutrient pollution.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

SPARROWs, Lakes, and Nutrients?

By Jeff Hollister

Dock extending into a lake with forested background.Based on the title above, you probably think I don’t know what I am talking about. I mean really, what do sparrows, lakes, and nutrients have in common? In this case, a lot. So much so, an inter-agency team of EPA researchers in Narragansett RI, and a colleague from the U.S. Geological Survey (USGS) in New Hampshire have been working together to better understand how these three seemingly disparate concepts can be linked together. Some of the results of this work are outlined in a recent publication in the Open Access journal, PLos One

The sparrow I am referring to isn’t small and feathered, it is a model developed and refined by the USGS. Since the late 1990’s, USGS has been developing SPARROW models which have been widely used to understand and predict the total amount of nutrients (among other materials) that streams are exposed to over the long-term. This is known as “nutrient load.” The models are important because they provide a picture over a very large extent of where nutrients might be relatively high.

However, when it comes to lakes, SPARROW doesn’t directly provide the information we need. For our research on lakes, we need reasonable estimates of the quantity of nutrients in a given volume of water (i.e., nitrogen and phosphorus concentration), not long term nutrient load for the year. This is important, because the higher the nutrient concentrations at any given time, the greater the chance of triggering algal blooms—and more blooms mean a greater probability of toxins released by algae reaching unhealthy levels.

In order to better estimate the nutrient concentrations, we needed to use the SPARROW model for total load, but also account for the differences between load and concentration. Our solution: combining field data, data on lake volume and the SPARROW Model.

In our paper “Estimating Summer Nutrient Concentrations in Northeastern Lakes from SPARROW Load Predictions and Modeled Lake Depth and Volume,” recently published in PLoS One, we describe how we combined modeling information from SPARROW, summertime nutrient concentrations collected during EPA’s 2007 National Lakes Assessment, and estimated lake volume (see this and this for more).

The end result of this effort is better predictions, by an average of 18.7% and 19.0% for nitrogen and phosphorus, respectively.

What is the meaning of this in terms of our environment, and importantly, the potential human health impacts? If we are able to better predict concentrations of nutrients it will hopefully also improve our ability to know where and when we might expect to see harmful algal blooms, specifically harmful cyanobacterial algal blooms. Cyanobacteria have been associated with many human health issues, from gastro-intestinal problems, to skin rash, and even a hypothesized association with Lou Gehrig’s Disease (for example, see this). So, in short, better predictions of nutrients, will, in the long run, improve our understanding of cyanobacteria and hopefully reduce the public’s exposure to a potential threat to health.

About the author: Jeff Hollister, a co-author on the study outlined in this blog post, is a research ecologist with an interest in landscape ecology, Geographic Information Systems (GIS), the statistical language R, and open science. The focus of Jeff’s work is to develop computational and statistics tools to help with the cyanobacteria groups research efforts. Jeff is also an outspoken advocate for open science and open access among his colleagues.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.

Seeing Green (and Predicting It)

By Dustin Renwick

Thick mat of green algae at the shore of a lakeWhen you live near a coast, summer means beaches. A relaxing inland getaway often involves the cool waters of a lake.

Except when the shoreline turns green.

Sometimes a mat of algae clogs fishing lines. Other times, lake foam makes the swimming area appear as if someone poured in a few St. Patrick’s Day green beers.

Those algae serve a natural function in the ecosystem. Yet an icky, slimy scene can ruin plans for a day on the water when conditions – generally warm, stagnant water rich in excess nitrogen, phosphorus,or other nutrient pollution – sparks rapid growth.

Ross Lunetta, EPA research physical scientist, leads a team of research and application scientists who proposed a Pathfinder Innovation Project to validate a new algorithm that uses satellite data for predicting algal blooms in freshwater systems.

Specifically, the team’s project targets cyanobacteria, known to make humans and animals sick with symptoms such as respiratory distress and skin rashes. On the basis of algae cell counts, more than a quarter of lakes nationwide have enough cyanobacteria for moderate to high risk according to the most recent National Lakes Assessment Report in 2009.

Tallying the density of cyanobacteria cells in a water body can provide an estimate of potential exposure risk. But sampling more than a handful of the nation’s lakes can be costly and slow. Plus, current satellite data and its analysis fall short.

Existing field measurement programs were not designed to provide data that researchers can readily use to calibrate and validate satellite-based observations. And satellites can’t discriminate between the sizes or the many species of cyanobacteria, some of which don’t produce toxins.

“It’s not necessarily the same species in Maine as it is in Florida,” Lunetta said. “These things can be very different in size.”

Not knowing the cell volume, which is species specific, makes calculations of blooms cell counts, impacts, and risks a challenge.

The team is working with TopCoder, an online community to bring in outside expertise and innovation through competitions and challenges and expand the search for solutions.

TopCoder represents nearly a half million software developers and algorithm specialists. The company’s process breaks large challenges into small chunks that can be coded, developed, or designed individually. Then TopCoder stacks all the pieces back together into a finished solution.

Imagine a neighborhood full of tinkerers, parts collectors and coding whiz-kids who could gather at your garage to diagnose and fix your car when the “check engine light” flashed. Each person could solve a problem within his or her specialty, and the cohesive result benefits from these specific skills.

The team’s predictive algorithm will take a few more months to design and even longer to validate, but the potential benefits are clear. Water forecasts and public health officials could alert anyone who might consider a day at the lake, and researchers could focus their efforts.

“If you have limited resources, and you can only collect five samples but you have 50 lakes,” Lunetta said, “you can pick the ones the model tells you will most likely become a problem.”

About the author: Dustin Renwick works as part of the innovation team in the EPA Office of Research and Development.

Editor's Note: The opinions expressed here are those of the author. They do not reflect EPA policy, endorsement, or action.

Please share this post. However, please don't change the title or the content. If you do make changes, don't attribute the edited title or content to EPA or the author.