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Harmful Algal Blooms (HABs)

Algal Bloom Reporting Form       Lake Advisories and Warnings

To report a Harmful Algal Bloom, use the online and phone-friendly Harmful Algal Bloom Report form or call the Health Department Division of Water Quality at 701.328.5210. For a map of lakes affected by HABs visit or click on


What is a HAB?
Typically, a HAB is an overgrowth of, cyanobacteria (blue-green algae) in surface water. Cyanobacteria are microscopic organisms found in all types of water. They are more like bacteria than plants, but because they live in water and use sunlight to create food (photosynthesis) they are often called "blue-green algae." Cyanobacteria are important to freshwater ecosystems because they make oxygen as a by-product of photosynthesis, and they are a food source for other organisms.

More Information:
NDSU Extension Ag - HABs Article

ND Game & Fish Department
                            Click on picture for
              Blue-Green Algae Video - ND Outdoors
         Blue-green Algae - ND Outdoors

Environmental Protection Agency - HABs
     Monitoring and Responding to Cyanobacteria and Cyanotoxins in Recreational Waters

Center for Disease Control - HABs

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The Harmful in HABs

Under certain environmental conditions, cyanobacteria can multiply quickly and form a bloom. Some species of cyanobacteria produce cyanotoxins that are released when the cells die and rupture. The toxins can cause harm to people, wildlife, livestock, pets and aquatic life. Almost every year in North Dakota, a few cases of pet and livestock deaths occur due to drinking water with HABs.

Additional effects of HABs include:

  • Blocking sunlight needed for other aquatic organisms
  • Raising treatment costs for public water supply systems and industries
  • Depleting dissolved oxygen as the algae dies off, resulting in fish kills

Specific human health effects are:

  • Allergic-like reactions
  • Skin rashes
  • Eye irritation
  • Gastroenteritis
  • Respiratory irritation
  • Neurological effects

What causes HABs?

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  • Excess nutrients (phosphorus and nitrogen)
  • Warm water temperatures
  • Slow-moving water
  • Sunlight

The major source of food for algae is nutrients that enter North Dakota lakes from:

  • Fertilizers (fields and yards)
  • Livestock and pet waste
  • Septic systems

A Long-term Problem
Once a waterbody has an excess of nutrients, the problem cannot be fixed overnight. Nutrients must be removed mechanically and/or allowed to be reduced naturally through internal cycling, while limiting the sources of nutrients in the watershed. Several North Dakota lakes have hypolimnetic drawdown systems that remove nutrient-rich water from the bottom of the lake. These systems can be effective at removing nutrients, but they do not address the nutrient sources.

What Can You Do?
Everyone plays a part in feeding the algae, from how you fertilize your lawn to the timing of fertilizing a 160-acre field, to whether or not you pick up your pet's waste, to the proper management of livestock waste.
Tips to reduce nutrients from entering runoff to our surface waters:

  • Sample the soil in your yard before you fertilize.Algal Bloom - 3
  • Leave your grass clippings on the lawn - they give nitrogen back to the lawn.
  • If you do need to fertilize, use only the recommended amount of product,
    and keep it off sidewalks and other hard surfaces.
  • Use field soil samples to calculate a nutrient budget for your crops.
  • Complete a comprehensive nutrient management plan for your farm.
  • Sample manure before applying it to the soil to ensure it is applied at the correct agronomic rate.


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