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A Study in Cyan

Fueled by phosphorus, nitrogen, and a warming climate, cyanobacteria pose a high-stakes conundrum for public-health officials and environmental policy makers.

By Dan Peckham

Across the Northeast and beyond, potentially harmful blooms of cyanobacteria threaten recreational and drinking water bodies alike. These bacteria release toxins that can spike to dangerous levels quickly.

This summer, scores of water bodies in the Northeast will experience these blooms, fueled by warm weather and nutrients from agricultural and residential runoff and from fixed discharges such as those from sewage-treatment plants.

State and local officials must be prepared to respond quickly to these events even as the science of and regulatory guidance for cyanobacteria and cyanotoxins continue to evolve.

Blue-green algae fouls boats and recreational dock

A bloom of cyanobacteria marbles the surface of Lake Waccabuc in Westchester County, N.Y., in June of 2012. JANET ANDERSEN

In fresh water, formation of blooms (commonly known as harmful algal blooms or HABs, but more accurately termed harmful cyanobacteria blooms or HCBs) occurs most often under a combination of high temperatures, abundant nutrients, and slow-moving or stagnant flow conditions. Marine species of cyanobacteria exist, and their blooms can be troublesome (red tides, for example), but this article will consider the challenges posed by freshwater species.

Calm summer days are times when once-clear lakes turn the color of pea soup or form a paint-like blue-green film on the surface, and this may spell trouble not only for swimmers but also for the public as a whole.

From a health perspective, the toxins cyanobacteria produce (cyanotoxins) are associated with skin rashes, gastrointestinal and respiratory disease, and liver damage for humans. Effects can be even more pronounced, potentially even fatal, in animals ranging from dogs to cattle.

HCBs have direct implications for the use of water bodies for recreation, the susceptibility of public water supplies to toxins, and the overall degradation of aquatic resources.

The cyan pigment in cyanobacteria leads to the common name “blue-green algae” as well as the “cyan” in the name for the bacteria. Cyanobacteria is the collective name for the phylum of bacteria that obtain their energy through photosynthesis, drawing nutrients from the depths and sunlight from the surface.

A thick bloom chokes the waters of the Rock RIver Wildlife Management Area near Lake Champlain in Vermont last summer. ANGELA SHAMBAUGH/STATE OF VT.

Scientific uncertainties continue to surround cyanobacteria and the toxins they produce. Why do blooms form in lakes some years, only to be completely absent the following year? What en­vironmental conditions trigger toxin production? Would HCBs be reduced by limiting either nitrogen or phosphorus, or are reductions of both nutrients needed?

What methods are most effec­tive for controlling and preventing blooms, and why do some methods prove effective in certain lakes and utterly ineffective in similar lakes? Might there be health risks to chronic exposure to very low levels of cyanotoxins, beyond the risks documented for short-term high-dose exposures?

In the Northeast, water supplies have not faced crises as great as the one that confronted Toledo, Ohio, in 2014. Nonetheless health agencies track blooms, and HCBs often lead to health warnings or beach closures.

In New York alone in 2015, the Department of Conservation noted blooms in 126 water bodies, from Oswego County to Brooklyn and from Erie County to eastern Long Island. Several blooms persisted for 24 weeks, from spring well into fall.

In February of this year, the Lake Champlain Basin Program announced plans to sample fish for cyanotoxins and other toxins to inform consumption advisories and lake management decisions. Potentially harmful cyanobacteria blooms appear in Lake Champlain each season.

Public-health messaging about cyanobacteria and cyanotoxins is challenging. From recreational water bodies to the tap in your house, public officials must communicate any potential health risks within the context of scientific unknowns, while avoiding creating an overly anxious attitude in the citizenry regarding waters that are perfectly safe the vast majority of the time. This can entail reducing multiple dimensions of risk into a single simple message.

Many communities source their drinking water from lakes that likely have cyanobacteria in them—cyanobacteria are present in almost any water environment, all around the globe—although extremely rarely in great enough numbers to warrant concern about health risks. Swimmers share the water with cyanobacteria as well, but as with drinking water, rarely involving levels of toxins that would cause harm.

New Guidance, New Questions

Harmful blooms of cyanobacteria rose to national attention during the 2014 Toledo drinking-water crisis. In August of that year, health authorities issued an urgent “do not drink” advisory to hundreds of thousands of Toledo, Ohio residents due to cyanotoxins in the supply. Toledo gets its drinking water from Lake Erie, which was experiencing a large HCB (see sidebar).

In June of 2015, EPA released drinking water health advisories for two cyanotoxins, which was the first national step towards guidance for this emerging environmental concern. Where there had been a paucity of national guidance regarding management of the public health risks associated with HCBs, state and local officials are no longer operating in a vacuum in this area. Yet questions remain.

  Bottle-Fed Infants and Pre‑School Age Children Adults and School Age Children
less than less than
Microcystins 0.3 µg/L 1.6 µg/L
Cylindrospermopsin 0.7 µg/L 3.0 µg/L
Source: EPA 2015. “2015 Drinking Water Health Advisories for Two Cyanobacterial Toxins” 820F15003.

The 2015 health advisories from EPA set guidelines for concentrations of cylindrospermopsin (a cyanotoxin) and microcystins (a class of cyanotoxins) at different levels of concentration for (1) children of pre-school age or younger and (2) older children and adults. Below these levels, adverse health effects are not anticipated to occur over an exposure period of ten days.

For instance, at microcystin concentrations of 1.6 micrograms per liter (μg/L) or greater in drinking water, there may be adverse health effects for infants, school age children, and even for adults after ten days of normal tap water consumption.

The guidelines from EPA are not, however, mandatory: as recommendations they create no official regulatory requirements at the state or local level. Furthermore, for another cyanotoxin (anatoxin), epa concluded that available scientific data were not sufficient to set a health advisory level at all.

The final EPA documents were not released until June 2015, leaving little time for states to react and adapt their programs to these new levels in advance of last summer’s bloom season. Many state and local officials are using this winter and spring to reevaluate their current programs in light of EPA guidance.

Following that guidance is not as simple as plugging the numbers into documents and procedures that are already on the books. States take into account several considerations when making decisions on exactly how to use EPA guidance. First and foremost, states are interested in reviewing the EPA’s work to ensure that studies referenced, methods used, and results reached align with state expectations for use in official regulation.

Beyond testing the rigor of the science behind the EPA’s guidance, states must determine how to address the intricacies of implementing a program that incorporates these cyanotoxin guidelines. Some of these specific pieces are not fully fleshed out in the national guidance.

For instance, what monitoring protocols should be required for facilities to determine if there is a risk of high levels of toxins, and who should fund this monitoring and the resulting laboratory tests? Is there capacity to run the necessary tests at labs in the state, and in a quick enough timeframe to make public health risk decisions? Are there health risks if concentrations exceed the epa guidance limits for five days, then below the limits for five days, and then return to high levels for six days?

What if concentrations are detected for 30 days in a row, but always below the health advisory limits? What message should local officials give the public if there are concentrations above the limit for young children but below the limit for adults (i.e., to avoid confusion is it better to issue a do-not-drink advisory for everyone whenever levels exceed limits for young children)?

Sidebar: Cyanotoxin Monitoring To Begin in 2018

State and local environmental and health officials are working through these and other considerations in preparation for this coming summer, with the understanding that climate change will likely bring warmer temperatures that may lead to more frequent occurrences. They foresee more frequent blooms in the future and want to be well-prepared.

Swirls of blue-green algae

RITA SPARACINO

Swimming Guidance

Cyanobacteria blooms affect not just drinking water sources but also recreational waters. National guidance regarding potentially harmful concentrations of cyanotoxins for recreation is yet to be released: state and local officials continue to fend for themselves when making decisions to close recreational water bodies that may pose health risks due to HCBs.

Recreational scenarios are further complicated because there are multiple avenues of exposure occurring at once: swimmers might ingest some water, in addition to toxin exposure on their skins and by inhaling airborne droplets of affected water that are splashed up by motor boats or an energetic flutter-kicking swimmer.

The risks of cyanotoxin exposure via contact and inhalation are less well understood scientifically than exposure via ingestion, and the nature of the interactions between the three is even less clear. Recent research has also hypothesized connections between long-term exposure to HCBs and neurological diseases such as Alzheimer’s.

National regulations are expected within the next year, but the process that states will need to follow to implement those rules will probably be similar to that for current drinking water guidance. Even then, as with anatoxin in drinking water, there will likely be some toxins for which there is not enough information to set health advisories for recreational waters.

Many stakeholders have expressed gratitude to EPA for releasing guidance on cyanotoxins as a baseline, but it is just that: a baseline or foundation upon which state and local officials must continue to make informed, if still difficult, health and environmental management decisions based in part on incomplete information.

Regional Leadership

With so many unknowns, states look to each other in the search for the best ways to approach HCBs, an area of concern that spans the charges of both environmental and health agencies.

NEIWPCC’s role in the Northeast around HCBs has centered on its HAB Workgroup, which has grown into a forum for conversations and sharing of successful approaches around the region. One topic of concern has been coordination of consistent messaging and guidance across Northeast states for HCB issues.

For questions ranging from the toxicity of aquatic organisms in bloom-affected waters to potential exposure from via inhalation of aerosolized droplets of water with toxins, NEIWPCC’s HAB workgroup of state, federal, and local stakeholders has convened discussions to improve members’ understanding and coordinate efforts around cyanobacteria.

One of the first questions from communities with HCB-affected water bodies is, “What can we do to fix the problem, and how much will it cost us?” Unfortunately, cyanobacteria pose a problem that defies simple answers. Solutions that are effective in one water body are often far less so under other local or regional conditions. With high startup costs and a potential to make things worse rather than better, local and state officials are hesitant to try untested methods.

A subset of NEIWPCC’s Harmful Algal Bloom Workgroup has consequently been focusing on HCB control methods to develop a list of key considerations and characteristics of each. This material includes overview-level information on the science behind each of the methods, their costs, and any water body characteristics under which they may be more or less effective.

The resulting product is a first step for local managers wondering how to solve HCB issues on their lakes. Managers of affected water bodies will need to work closely with state permitting departments, and likely with lake management consultants as well, to implement an effective solution.

The HAB Workgroup has its work cut out for it this year. Its agenda will likely include the 2015 EPA drinking water guidance and any upcoming recreational guidance.

One subgroup is working on guidance and protocols for monitoring. Other projects simply involve compiling and organizing up-to-date information, such as a collection of practices by state and a list of laboratories that test for toxins. The workgroup also plans to compile case studies of various methods in action, both within the region and further afield. The group has also considered documenting blooms regionally for informational and reporting purposes.

The group will continue to assess what has worked and what policies and procedures may need to be changed based on emerging science and ex­perience. In an evolving field like HCBs, officials must make many choices using the information available to them. The HAB Workgroup will continue to provide the region’s experts with as much information as possible to inform these decisions and protect the health of water bodies and citizens in the Northeast.


Daniel Peckham was an environmental analyst in NEIWPCC’s Water Quality Division from 2014 to 2016.

This story is available as a reprint, one of a series from NEIWPCC. It was originally published in the March, 2016, issue of the Interstate Water Report, the predecessor of Interstate Waters.

Cyanobacteria cells form a bundle of looped strands

Strands of Cyanophyta Anabaena, a species of cyanobacteria. The scale line indicateds the length of 100 micrometers, which is a tenth of a millimeter. JAMIE CARR/MA DCR

A Study in Cyan

This story is available as a reprint, one of a series from NEIWPCC. It was originally published in the March, 2016, issue of the Interstate Water Report, the predecessor of Interstate Waters.

Toledo Water Crisis

“Do Not Drink the Water”

Cyanotoxins in Lake Erie led abruptly to a water-supply emergency in Toledo in 2014.

Read the story of the crisis in the words of public bulletins published on the City’s web page.

Related Content

In addition to Toledo Water Crisis, the following two sidebars were published with this story: