Water Quality FAQs

  • Q: What are cyanotoxins?
    A: Cyanotoxins are produced by what is commonly referred to as blue-green algae. This algae is found naturally in slow-moving surface waters such as lakes and reservoirs. These toxins can cause serious illness or death in pets, livestock and wildlife. Cyanotoxins can also make people sick, and in sensitive individuals, cause...

    A: Cyanotoxins are produced by what is commonly referred to as blue-green algae. This algae is found naturally in slow-moving surface waters such as lakes and reservoirs. These toxins can cause serious illness or death in pets, livestock and wildlife. Cyanotoxins can also make people sick, and in sensitive individuals, cause a red, raised rash or irritation.


  • Q: How does EWEB monitor for these toxins?
    A: For many years we have been monitoring Blue River Reservoir and Cougar Reservoir for algae blooms and toxins. Both reservoirs flow into the upper McKenzie River. We regularly monitor and test for the toxins in the reservoirs when we detect a bloom. Staff also test at the outfall locations, where the water drains into the...

    A: For many years we have been monitoring Blue River Reservoir and Cougar Reservoir for algae blooms and toxins. Both reservoirs flow into the upper McKenzie River. We regularly monitor and test for the toxins in the reservoirs when we detect a bloom. Staff also test at the outfall locations, where the water drains into the McKenzie River, and at Hayden Bridge, where our water treatment intake is located.


  • Q: What does EWEB do if toxins are detected?
    A: We increase monitoring and sampling, and if warranted, we modify our treatment process to include adding powdered activated carbon to the pre-filtration process and adjust disinfection strategies to prevent potential toxins from entering the finished water. This increased monitoring also includes testing our treated...

    A: We  increase monitoring and sampling, and if warranted, we modify our treatment process to include adding powdered activated carbon to the pre-filtration process and adjust disinfection strategies to prevent potential toxins from entering the finished water. This increased monitoring also includes testing our treated drinking water.


  • Q: At what levels do cyanotoxins in drinking water become a health concern?
    A: There are no federal standards for cyanotoxins in drinking water. The Oregon Health Authority has adopted provisional health-based guideline values for the four cyanotoxins of greatest concern in our drinking water. The four cyanotoxins are: anatoxin-a, cylindrospermopsin, microcystins and saxitoxins. Below are the Oregon...

    A: There are no federal standards for cyanotoxins in drinking water. The Oregon Health Authority has adopted provisional health-based guideline values for the four cyanotoxins of greatest concern in our drinking water. The four cyanotoxins are: anatoxin-a, cylindrospermopsin, microcystins and saxitoxins.

    Below are the Oregon Health Authority Guideline Values (expressed in parts per billion):

    Drinking Water Guidance Value: Microcystin/   Cylindrospermopsin/   Saxitoxin/ Anatoxin-a
    Adults 1.6   3   1.6   3
    Ages 5 years and younger 0.3   0.7   0.3   0.7

  • Q: Where can I find more information about cyanotoxins?
    A: Additional Information and Resources: Oregon Health Authority - Cyanotoxins in Drinking Water FAQs Environmental Protection Agency - Cyanotoxins in Drinking Water