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Spoiling the Fun: Harmful Algal Blooms & Bacteria at Iowa Beaches

Spoiling the FunHarmful Algal Blooms (HABs)

About HABs

Harmful algal blooms (also known as cyanobacteria) are overgrowths of blue-green algae in water. HABs can produce dangerous toxins that present significant threats to our health, our environment, and our economy.



In combination with sunlight and slower-moving water, HABs are caused by nutrient pollution (excess nitrogen and phosphorus). According to the U.S. EPA, "animal manure, excess fertilizer applied to crops and fields, and soil erosion make agriculture one of the largest sources of nitrogen and phosphorus pollution in the country."

Other sources of nutrient pollution, according to the EPA, may include: stormwater runoff, wastewater, domestic fertilizer use/yard waste, pet waste, etc.

Environmental Impacts

According to the EPA,

  • Toxins sometime present in HABs can "kill fish and other animals."  These toxins are consumed by small fish/shellfish, and then "move up the food chain" to other larger animals like turtles, birds, other fish, etc.
  • HABs can also harm fish and aquatic life by "blocking out sunlight and clogging fish gills."

Economic Impacts

Harmful algal blooms (HABs) resulting from nutrient pollution can increase a variety of costs, ranging from drinking water treatment to medical costs associated with HAB exposure. HABs can also decrease spending on recreational lake tourism and the associated economic benefits. 

Health Impacts

According to the EPA, direct exposure to harmful algal blooms can cause serious health problems, including: 

  • Rashes
  • Stomach or liver illness
  • Respiratory problems
  • Neurological affects

Read more about health impacts of exposure, including risks for vulnerable populations including children and pets.