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Communicating about Cyanobacterial Blooms and Toxins in Recreational Waters

EPA designed the tools on this page to support states, tribes, territories, and local governments as they develop their own risk communication materials. The tools can help water managers inform people using recreational waters, as well as pet and livestock owners, of the health risks associated with cyanobacteria and their toxins in lakes, rivers or other recreational water bodies. 

Communication to the public may occur through signage at the recreational water body; radio and TV announcements; and/or social media. Messages should clearly define levels of risk and of potential contamination, such as the exposure potential for specific recreational activities.  Managers should also be aware that toxins may be transported and affect downstream waters.

DISCLAIMER: This information does not impose legally binding requirements on EPA, states, tribes, or the public, nor does it confer legal rights. It does not constitute a regulation, nor does it change or substitute for any Clean Water Act provision or EPA regulation. Any mention of trade names, products, or services does not convey and should not be interpreted as conveying official EPA approval, endorsement, or recommendation for use.

On this page:

Good Practices when Developing Notifications for the Public

Managers typically use a combination of notification methods to address the diversity of stakeholders in their community and the nonresidents who might travel to a particular recreational water body. For example, signs posted at the beach, which are necessarily limited in size and scope, can reference a website, Twitter handle, or other source with more detailed or up-to-date information. States, local public health departments, or managers may also choose to take different actions based on jurisdiction of the water body and the severity of the problem. That is, posting an advisory or warning might be appropriate when the cyanobacterial cell density levels or cyanotoxin levels are slightly above a pre-determined action level (e.g., “Algal Bloom Advisory: Levels of toxins may cause illness in recreating children”); whereas closing public access to a water body might be appropriate when increased cyanotoxin levels present a greater risk.

A notification should be simple, clear, and authoritative. The core elements of a notification include the following:

  • Key Notification Message: Closure or Warning Issued; Closure or Warning Lifted.
  • List of unsafe activities (e.g., swimming, wading, fishing).
  • List of approved activities (e.g., boating, canoeing, kayaking)
  • Reason, duration and cause for the notification (e.g., high levels of cyanotoxins or cyanobacteria, HAB event, HAB event suspected and sampling underway).
  • Location affected by the notification (i.e., because cyanobacterial blooms are often transient and variable in their spatial distribution, it is important to convey the message that recreational activities may be restricted to a specific area of the water body such as a swimming beach or dock).
  • Potential consequences of swimming in/contact with contaminated water (e.g., gastrointestinal irritation).
  • Actions taken by beach managers to monitor the bloom.
  • How to get information on health risks and/or report related illness in humans, pets or livestock (e.g., hotline).
  • Agency contact information.

As a precaution, the World Health Organization (WHO) recommends that the following guidance should be included in public information relating to cyanobacterial blooms:

  • Avoid areas with visible cyanobacterial or algal concentrations and/or scums in the water as well as on the shore. Direct contact and swallowing appreciable amounts are associated with the greatest health risk.

  • Where no scums are visible, but the water shows strong greenish discoloration and turbidity, test if you can still see your feet when standing knee-deep in the water (after wading in without stirring up sediment). If not, avoid bathing— or at least avoid ingestion of water, i.e., submersion of your head. In such situations, avoid waterskiing because of potentially substantial exposure to aerosol toxins.

  • If sailing, sailboarding or undertaking any other activity likely to involve accidental water immersion in the presence of cyanobacterial or algal blooms, wear clothing that is close fitting in the openings. The use of wet suits for water sports may result in a greater risk of rashes, because cyanobacterial or algal material in the water trapped inside the wet suit will be in contact with the skin for long periods of time.

  • After coming ashore, shower or wash yourself to remove cyanobacterial or algal material.

  • Wash and dry all clothing and equipment after contact with cyanobacterial or algal blooms and scum.

For more information on the WHO guidelines see:

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Templates and Generic Examples

EPA suggests these templates and generic examples as starting places for entities needing to communicate with the public using various means. Entities can use these to create and customize their own materials, whether digital or hard copy.   Note that most of these files are in .docx (Word) format. Free Viewers

Social Media

Press Releases

Background Information for the Public

EPA keeps basic information about cyanoHABs updated on our website as science evolves. Entities can utilize this information by linking to it in their digital outreach materials or by creating their own hard copy materials.  Additionally, EPA has developed infographics to help educate the public on HABs basics. These infographics can be used by our partners in other federal agencies in state, territorial, tribal and local governments to help educate recreators about the potential dangers of HABs in both marine and freshwaters.

Contact Information for the Public

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State/Tribal Examples

The following links exit the site ExitMany states have developed signage and other documents to notify members of the public about cyanobacterial blooms and potential health effects. We have included a few examples here:

  • The Environmental Health Investigations Branch of the California Department of Public Health created sign icons to represent various allowable and prohibited activities (e.g., to wash fish before eating or for pets and humans to avoid contact with cyanobacteria). The icons have been used to create signs with simple, clear messages.

  • Several state government departments in Indiana collaborated on a sign which contains information on how to identify a HAB, and the effects a HAB may have on people, pets and fish, and a 4-level alert system based on water quality testing results (low risk, advisory, caution, and beach closed).

  • This Massachusetts webpage provides links to several resources including guidelines and fact sheets, photos to identify cyanobacterial blooms, brochures in 9 languages, a pet safety poster (English and Spanish), and links to CDC and EPA pages.

  • The Upper Mississippi River (UMR) HAB Work Group developed the manual for states in the UMR basin. The document contains example press releases from several states along the UMR (pages 23-40).

  • Nebraska will deploy this signage at its 52 public lakes and recreational waters in the 2017 swim season at the request of recreational water managers across the state. The signs will use simple symbols (circle with slashes over certain activities, not others) to identify which activities are permitted (e.g., fishing, swimming, waterskiing, etc.).

  • This example warns people not to swim if they cannot see their feet in knee-deep water, to keep their pets away from waters that may be affected by HABs, and to consult their local health department, the state Department of Natural Resources, or the Department of Health Services for more information.

  • These Yurok Tribe guidelines include information about when to post and when to remove public health advisory signs based on microcystin cell density levels.

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