Toxic Algae

What are Harmful Algal Blooms (HAB)?

Harmful Algal Blooms occur when blue-green algae, also called cyanobacteria, grow quickly in water, often (but not always) in response to increases in nutrients and hot, dry, still weather conditions. Cyanobacteria intermittently, but not always, produce toxins, potentially harmful to the health of the environment, plants, animals, and people. There are many different toxins produced by cyanobacteria. The most commonly tested toxin, or “index toxin” in our area is Microcystin LR. Its presence in concentrations higher than 4 mcg/L, is considered potentially harmful and is also indicative of the possible production of other toxins by the cyanobacteria.

How do the toxins in HAB cause illness?

Rarely, there may be skin rashes or itching. Mostly, however, the toxins must be ingested to be a problem. Therefore, for the most part, it is safe to swim in areas of the lake that are clear.   But, be reasonable; do not swim through algal bloom. Remember: Do not allow small children to play in shallow water that is not clear. Keep pets out of these areas.  Do not drink lake water. When in Doubt, Stay Out.

What can I do to decrease or prevent algal blooms?

Toxic algae need food– phosphorus and nitrogen– to grow.

Don’t add harmful nutrients to the lake!

  • Use only phosphorus free fertilizers (middle number is zero) and use them sparingly
  • Plant a buffer zone of deep rooted grasses, shrubs, or natural vegetation at the shoreline. Do not cut down trees in the watershed of the lake.
  • Have your septic system inspected and pumped at least every 3 years.  Make repairs promptly and, if necessary, replace outdated or  ineffective systems
  • Use phosphate-free laundry and dishwashing soap
  • Compost or properly dispose of leaves, lawn clippings, garden waste, goose poop, etc. Not in the lake, please!

Is HAB the same as Cyanobacteria?

Yes! HAB (Harmful Algal Blooms), cyanobacteria, toxic algae, and blue-green algae all refer to the same  organism.

Useful Links

For more information about toxic algae in Roaring Brook Lake

Photo Gallery: What do Harmful Algal Blooms Look Like

NY State DOH

NY State DEC

EPA drinking water advisory

Toxic drinking water in Ohio, Washington Post 2014