Log in to view your state's edition
You are not logged in
Bookmark and Share
September 19, 2019
EPA forming assistance policy for toxic algal blooms

In a notice, the EPA is soliciting public comment on the development of a policy to determine when harmful algal blooms (HABs) in freshwater are events of “national significance” and therefore entitled to federal mitigation assistance.

MikNik / Shutterstock

HABs are caused by photosynthetic organisms that, under certain conditions, form large accumulations of algae. In freshwater, cyanobacteria make up the major HAB-forming taxon. Cyanobacteria are microorganisms that can produce harmful cyanotoxinsthat, if ingested in sufficient amounts, can kill fish, shellfish, livestock, and wildlife and can adversely impact human health. Algal blooms can also harm aquatic environments by depleting oxygen needed to sustain freshwater aquatic life, a phenomenon called hypoxia.


In 2014, a large HAB in Lake Erie that contaminated the drinking water for about 500,000 people in Toledo, Ohio, brought the scourge of HABs into the national spotlight, but HABs are hardly a new occurrence. Congress recognized the danger of HABs in 1998 when it passed the Harmful Algal Bloom and Hypoxia Research and Control Act (HABHRCA). The Act empowered the National Oceanic and Atmospheric Administration (NOAA) to advance the scientific understanding and ability to detect, monitor, assess, and predict HAB and hypoxia events. The HABHRCA has been amended three times—most recently in 2018. That action provides NOAA with the authority to make a determination that a coastal or marine HAB or hypoxia event is of “national significance” and therefore entitled to federal assistance to mitigate the detrimental environmental, economic, subsistence-use, and public health effects of the event. The legislation provided the EPA with the same authority for freshwater HAB or hypoxia events.

In July 2019, NOAA solicited public comments on developing a national significance policy for marine and coastal HAB events; the EPA has followed with the current solicitation to inform a national significance policy for freshwater HAB events.

Determining factors

The most recent legislation indicated that a determination that an HAB is of national significance must be based on at least six factors. Those factors and questions for which the EPA is soliciting comment are as follows:

  • Toxicity. Which metrics should the EPA use to assess toxicity of an HAB event to determine national significance? For example, should the EPA consider reports of human or animal illnesses or deaths or adverse effects on aquatic life?
  • Severity. Which metrics should the EPA use to determine whether the severity of a hypoxic event makes it nationally significant? For example, should the severity of the event include consideration of human health, economic, and environmental impacts?
  • Potential to spread. Which metrics should the EPA use to determine whether the potential for the spread of an HAB or hypoxia event makes it nationally significant? For example, should historical information be used to inform a decision on the potential for an HAB or hypoxic event to spread?
  • Economic impact. Which metrics should the EPA use for economic impact in determining national significance? For example, should economic status (i.e.,makeup of the state, local, and tribal government economy and its reliance on the affected waterway for tourism or drinking water) be considered when determining the national significance of an event?
  • Relative size of an event in relation to the past five occurrences of HABs or hypoxic events that occur on a recurrent or annual basis. Which metrics should the EPA use for recurrence to determine national significance and specifically whether the size and scope of an event or occurrence are significant relative to past events? For example, should the EPA assign a specific number of years, seasons, or months between events in considering national significance?
  • Geographic scope. Which metrics should the EPA use to determine that an HAB or hypoxic event is nationally significant because it has the potential to affect more than one state or cross an international boundary? For example, for an event that has impacted or might impact more than one state, should the EPA make a single determination for that event applicable to all states impacted, including those states that may be impacted by expansion, movement, or intensification of the event?

The EPA says it will consider comments on whether additional criteria should be used to determine national significance. These criteria might include the state’s access to critical resources (e.g., technical expertise); whether the HAB event impacts drinking water; and which information a state should provide to the EPA when requesting determination of an event of national significance.

Twitter   Facebook   Linked In
Follow Us