Harmful Algal Blooms: What You Should Know

Friday August 9, 2019

Why the water turns that funny green and how to protect your family and pets

In mid-summer and into the fall, people may see a strange substance floating in or on local ponds, lakes, rivers, or streams. It may look like clumps of grass clippings or curds of green cottage cheese -- or there may be a strong green color in the water that looks like spilled paint or pea soup. What you are looking at most likely is blue-green algae or Cyanobacteria. Blue green algae are microscopic organisms, that are actually bacteria that is natural and common in many lakes. When conditions are right, such as plenty of nutrients, warm temperatures, plenty of sunlight, and relatively calm conditions, they grow fast or ‘bloom’.

An algal bloom is characterized by a pea green tint to the water. Blooms sometimes appear to have the consistency of paint or scum and floats on the surface. The severity of a bloom will fluctuate over the course of a day, depending on wind speed, direction and light intensity. The following actions can be taken to reduce health risks commonly associated with blooms:

• Avoid areas with visible algae and/or scums. Direct contact and ingestion are associated with the greatest health risk.

• If no scums are visible, but water shows a strong greenish discoloration such that you cannot see your feet when standing knee deep (after sediment has settled) avoid bathing, immersion of head, and/or ingestion.

• Avoid waterskiing in visible scums or waters with a strong greenish coloration as described above because of the potentially substantial risk of exposure to aerosols.

• If sailing, sail boarding or undertaking any other activity likely to involve accidental immersion, wear clothing that is loose fitting in the openings. Use of wet suits for water sports may result in greater risk of rashes, as the algal material trapped in the wet suit will be in contact with the skin for longer periods of time.

• After coming ashore, shower or wash to remove algal material.

Paul Andriacchi, Environmental Health Director advises, “remember to keep pets out of water with algal blooms too, and if they do come into contact with the water, take these special precautions.”

• Keep pets out of areas of the water that contain scum or water that looks like spilled paint or is green.

• If you pet does come into contact with what could be an algal bloom, rinse them off with fresh water right away to keep them from ingesting the water by licking the contaminated water from their coat.

If you, your children, or pets become sick after contact with water that appears to have an algal bloom, contact your healthcare provider or veterinarian.

The Michigan Department of Environment, Great Lakes, and Energy (EGLE) is developing an approach to monitor, assess, and report on harmful algal conditions, to improve our understanding of the nature, extent, and frequency of harmful algal blooms (HAB). EGLE defines a HAB as: “An algal bloom in recreational waters is harmful if microcystin levels are at or above the 20 ug/L World Health Organization non-drinking water guideline, or other algal toxins are at or above appropriate guidelines that have been reviewed by EGLE-WRD.”
More information on blue-green algae