Algae blooms: Guidance for drinking water providers

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What problems do algae blooms cause for drinking water systems?

Algae in drinking water sources can cause the water to taste or smell bad. Taste and odor are not regulated but create customer concerns about water quality and safety. Most complaints water utilities receive are about taste and odor, and these issues can last for prolonged periods. In addition to taste and odor problems, toxins from harmful algae blooms can create a public health risk. Removing toxins in a safe and cost-effective way can be a challenge for treatment facilities, and not all are equipped to do so.  
Are toxic algae in drinking water regulated?

No, and they are not routinely tested for either. After Toledo, Ohio experienced a severe problem with harmful algae blooms in 2014, the EPA developed health advisory guidance for water systems and suggested a multiple step process to identify and address problems. Following this guidance is not a regulatory requirement.
How can I tell if an algae bloom is harmful?

The only way to be certain if an algae bloom is harmful is to run specific water tests. The Colorado Laboratory Services Division is one lab that can complete these tests. 
a harmful algae bloom affect a public water supply?

Yes. This happened in Toledo, Ohio in 2014. The economic consequences of such an event can be severe.  
How we can help

Drinking water providers can contact the Water Quality Control Division at 303-692-3500 with questions about algae blooms. We can help water utilities that experience taste and odor problems. This includes ideas about customer communication and steps utilities can take to manage algae blooms and best treat their drinking water.


To learn more about algae blooms and health, call 303-692-2700 or visit our harmful algae blooms web page.