Harmful Algae Blooms

Drinking water questions?

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We monitor the McKenzie Watershed for blue-green algae blooms throughout the spring and summer to make sure your drinking water is safe. When we spot an algae bloom in Cougar Reservoir or Blue River Reservoir, we immediately begin sampling for cyanotoxins.

Blue-green algae are found naturally in lakes and reservoirs. Some species of algae create toxins (cyanotoxins). 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. In addition to sampling for toxins at and below the reservoirs, we also test for toxins in the lower McKenzie at Hayden Bridge, where our treatment plant water intake is located.

If toxins are detected at the intake, 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. We also increase our monitoring and sampling protocols, which includes testing treated drinking water.

Related Programs

More about safe drinking water


The U.S. Environmental Protection Agency provides additional information about drinking water.

Oregon Health Authority
Oregon drinking water services

Oregon drinking water services

Learn more about drinking water from the Oregon Health Authority.