Trinity County Releases Update on Harmful Algal Bloom in Barry Creek

unsafe to drink tc environmental Health

Press release from Trinity County Health and Human Services:


Lab results confirmed the presence of the cyanotoxin microcystin in Barry Creek, near the headwaters of the Mad River. However, the concentration in the water was below drinking water health advisory levels. This harmful algal bloom (HAB) is caused by algal mats. Cyanotoxin concentrations within algal mats can be high, while cyanotoxin concentrations in the surrounding water are low. Therefore, we recommend avoiding contact with algal mat material. Animals, especially dogs and livestock, that consume algal mats may be at risk of cyanotoxin poisoning. If you suspect a cyanotoxin related illness, contact a medical professional or veterinarian immediately, and email [email protected].

For more information on how cyanotoxins can affect your livestock and for information to share with your veterinarian, go to:

For more specific information regarding potentially toxic algal mats, go to:

For other questions or needs for fire recovery call: (530) 623-8223 or visit

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  • Well, at least they got the name of the stream right this time. Okay, don’t eat algal mats. Got it!

    • Can somebody who knows please comment? I had heard the cyanotoxins in the algae in the slow-moving water could kill dogs. Have heard this for years. especially in our Souh Fork Eel as it’s the first local river to get low in the summer…This is the first time I’m seeing that this only applies to algae mats! I can keep my dogs away from drinking up mats of algae but I have been erring on the side of safety and just keeping my dogs away the river when it gets low and algaed-up…. From this article I’m thinking now that they are fine to drink from the river in a dry September just not licking at the mats?

      • We love our dogs so erring on the side of caution is always best. While toxins are concentrated in the algae, it stand to reason that distance from the bloom will reduce its’ concentration while the waters upstream will remain as they were.

      • I would not let my dogs near any river with an algae warning. Just because it is in the mats doesn’t mean it hasn’t been disturbed prior to your arrival. I live on the Eel and my babies aren’t allowed in it come July, unless it is a high water year. Too many dogs have died. So not worth the risk.

  • The best available source of information for the questions people area asking is at the websites mentioned in the article. Read that first! Educate, don’t speculate.

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