BISMARCK — The North Dakota Department of Environmental Quality is reminding the public that hot summer weather contributes to the production of blue-green algae in bodies of water.

Blue-green algae discolors the water and can cause foam, scum or mats to appear on the surface. In severe cases, the water can have the appearance of spilled green paint or green pea soup. Blue-green algae can also produce toxins in the water called cyanotoxins.

People and animals that swallow water containing cyanotoxins can become sick with diarrhea and vomiting, numb lips, tingling fingers and toes, dizziness or rashes, hives or skin blisters. In severe cases, cyanotoxins can result in death. There are no known antidotes.

Children are at a higher risk than adults because of their smaller size.

The NDDEQ tests water for toxins and issues advisories to the public. Because it can take time to receive test results, people are urged to be cautious and avoid waters that look discolored, scummy or have a foul odor.

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Algae blooms are most common in North Dakota in late summer, however, it only takes a few hot days to cause the algae to bloom, according to Aaron Larsen with the NDDEQ Division of Water Quality.

The NDDEQ and the Department of Agriculture recommend these steps to avoid exposure to cyanotoxins:

  • Respect advisories announced by public health authorities.
  • 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.
  • If you accidentally swim in water that might have an algae bloom, rinse off with fresh water as soon as possible.
  • Do not let pets or livestock swim in or drink from areas where the water is discolored or where you see foam, scum or mats of algae.
  • If pets swim in scummy water, rinse them off immediately – do not let them lick the algae off.
  • Do not irrigate lawns or golf courses with pond water that looks scummy or smells bad.

For more information about the effects of blue-green algae blooms on pets and livestock, contact the North Dakota Department of Agriculture, Animal Health Division at 701-328-2655.

For more information on public health issues or to report a suspected algae bloom, go to or call the North Dakota Department of Environmental Quality at 701-328-5210.