Harmful Algal Blooms (HABs)
Know it.
Blue-green algae can look like a crust on the water, grass clippings, green cottage cheese, scum or like spilled green paint or green pea soup.
Avoid it.
- Respect advisories and warnings announced by the NDDEQ. All water advisories and warnings are posted on this page.
- Do not swim, water ski, or boat in areas where the water is discolored or where you see foam, scum or mats of green or blue-green algae on the water; or let pets swim in or drink from affected waters.
- If you or your pet accidentally swims in water that might have a cyanobacteria bloom, rinse off with fresh water as soon as possible.
- Do not irrigate lawns with pond or lake water that looks scummy or has an awful odor.
Report it.
Report suspected blue-green algae blooms to the NDDEQ by using the online form linked above, calling 701-328-5210 or emailing DEQ-HAB@nd.gov. Because it can take time to receive laboratory test results, we urge people to be cautious and avoid waters that look discolored, scummy, or have a foul odor.
Active Harmful Algal Bloom Advisories/Warnings:
The NDDEQ responds to reported blooms across the state and tests water for toxins. If toxins are at an unsafe level, the NDDEQ issues advisories and warnings to the public.
An Advisory means a blue-green algae bloom is present in portions of the waterbody. The blue-green algae may be harmful to humans and pets. To reduce the risk of illness:
- Do not swim, waterski, or tube if the water looks like spilled green paint or pea soup.
- Avoid swallowing water and watch small children and pets who may ingest water.
- Rinse off with clean water after swimming.
- Stay away from areas of scum when boating.
A Warning means a blue-green algae bloom is present over a significant portion of the lake and excessive microcystin levels have been measured.
- Avoid contact with the water.
- Individuals should not take part in contact recreational activities (e.g., swimming, water skiing, kayaking and paddle boarding).
- Do not allow pets in the water.
Current List of Lakes in Table Format
Current Harmful Algal Bloom Map
The Harmful in Harmful Algal Bloom
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.
Under certain environmental conditions, cyanobacteria (blue-gren algae) 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.
Specific human health effects are:
- Allergic-like reactions
- Skin rashes
- Eye irritation
- Gastroenteritis
- Respiratory irritation
- Neurological effects
What Grows Algae?
- 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
The Source of the 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.
- 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.
More Information
NDSU Extension Ag Article - June 2016
Livestock Water Testing Guidelines
ND Game & Fish Department
Centers for Disease Control
