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.

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