Blue Green Algae

Asked August 13, 2019, 4:19 AM EDT

Hello, how would I know that I have blue green algae in our irrigation ponds, and if yes, how to get rid of them. We have heard a lot about how toxic they are to animals, especially dogs. Our dogs love to swim in the ponds, and now we are worried. I would appreciate any help you can give us. Are there any test kits we could use? Thank you very much in advance, and have a great day! Angela Sommers 541-842-8584

Josephine County Oregon

1 Response

Greetings Angela,

First, my standard caveat: In spite of being based in Ohio, pond management questions tend to default to me when there isn't an Extension educator in any given US county who feels they can field such questions. I have good practical knowledge of pond management, but from the perspective of a cool-temperate-zone Ohioan and in near-complete ignorance of local services available or laws outside my state.

That said, blue-green algae issues are pretty similar to any fresh waters in which they arise. Regarding identification, this fact sheet coauthors and I first published in 2010 may still be of some use(note that the contact info it gives for me is outdated): https://ohioseagrant.osu.edu/products/ab280/habs-in-ohio-waters (some name changes since: Anabaena has been renamed Dolichospermum, and Lyngbya has been renamed Microseira). Here’s an article I wrote on managing against related problems in ponds: https://senr.osu.edu/sites/senr/files/imce/files/extension_outreach/ponds_fish_aq_mgmt/OhioPondNews/OPN_SP15.pdf. One of the most common blooming genera in recent times is Microcystis; it tends to form bright green, streaked surface scums in calm weather. In addition to the fact sheet note the attached images that I shot on a pond with which I'm working in Ohio. If you see any green scums that give you pause, I strongly encourage you to restrict access by your dogs.

Test "kits" available to the public tend to be useful in limited ranges and are still somewhat limited by the users' savvy in using such tools. A toxin test at a single point in time is of limited utility because toxin production by a bloom can change very rapidly. Here is an excerpt from a slide presentation of mine:

Many species can produce toxins, but variably so.

  • Single point-in-time tests don’t reveal much; meaningful toxin monitoring of a bloom site over time becomes prohibitively expensive.
  • Give monitoring priority on sites used for commercial purposes (like irrigation or aquaculture), domestic water supplies, or with public contact/access.
  • Less so (like probably not at all) on sites used for casual recreation or aesthetics (instead, limit human contact and restrict access by domestic animals).

Finally, I also encourage you to contact your local Extension office directly to help identify any local contractors who may work with or identify blue-green algae blooms: https://extension.oregonstate.edu/josephine

Good luck with this.
Eugene