Harmful Algal Blooms (HABs) are overgrowths of algae in waterbodies.
Under favorable conditions, certain species of algae, cyanobacteria, can release toxins, called cyanotoxins, that are harmful to the environment and
living creatures, including human beings. The main avenues for human exposure to cyanotoxins is either through direct
contact during recreational activities or by ingestion of contaminated drinking water. HABs are also responsible for creating dead zones in waterbodies,
which can have negative impacts on aquatic life and the environment.
As algal toxins have human health implications, they need to be removed from the drinking water. This in turn can increase treatment costs. There are many factors that contribute to the growth of HABs. While HABs occur naturally in waterways, they are exacerbated by overfeeding of nutrients (nitrogen and phosphorus) resulting from human activities. Climate change is expected to bring about warmer temperatures which can add to the problem.
This map displays locations in the Potomac basin where HABs are being monitored. Some of these locations are long-term monitoring sites while others are response based. For more information about a site, please click on an individual monitoring location. The complete dataset with contact information can also be downloaded as an Excel Spreadsheet.
For more information on HABs, the EPA provides a comprehensive overview here.