Harmful Algal Blooms (HABs)
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.
NDSU Extension Ag - HABs Article
ND Game & Fish Department
Environmental Protection Agency - HABs
Center for Disease Control - HABs
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
- Respiratory irritation
- Neurological effects
What causes HABs?
- Excess nutrients (phosphorus and nitrogen)
- Warm water temperatures
- Slow-moving water
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.
reduce nutrients from entering runoff to our surface waters:
- Sample the soil in your yard before you fertilize.
- 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.