Harmful Algal Blooms (HABs) refer to toxic algae blooms, which can affect humans, pets, and ecosystems.

Canoes sit out of the water near an algae bloom fed by nutrients

HABs are toxic forms of cyanobacteria that have characteristics similar to algae as well as bacteria. They are prokaryotic like bacteria, yet undergo photosynthetic processes much like their eukaryotic algal counterparts.

HABS occur in both freshwater and marine environments. Many freshwater HABs prefer warm water and nutrient rich waterbodies. Nutrient sources such as agricultural and stormwater runoff and wastewater effluent have been linked to higher rates of these bacteria.

Harmful algal blooms and their toxins are an increasing concern across the continent and globally. The frequency of HAB occurrence is on the rise and cyanobacteria toxicity has been associated with human health impacts including skin rashes, gastrointestinal and respiratory disease, and liver damage. HABs also have direct implications to the use of recreational waterbodies for contact recreation, the susceptibility of public water supplies to toxins, and the overall degradation of our aquatic resources.

Visit the EPA’s HAB webpage for more information.


NEIWPCC’s Role

In conjunction with our member states and the U.S. Environmental Protection Agency, NEIWPCC continues to address concerns related to HABs and cyanobacteria through our various workgroups, including the Harmful Algal Blooms Workgroup, and at NEIWPCC events. In 2022 and 2024, NEIWPCC hosted the U.S. Symposium on Harmful Algae, bringing together researchers and other professionals from across the country to share their expertise, challenges and solutions.

In 2016, NEIWPCC, EPA Region 1 and CitiSci.org launched a smartphone app, bloomWatch. The app enables community scientists to help document potentially harmful blooms by submitting a photograph and other information from a smartphone or tablet.

For more information, contact Maryann Dugan, coordinator of our HABs Workgroup.


Additional Resources