The City of Salem says small amounts of cyanotoxins were found in the water prior to the city's treatment plant.
The levels of toxins are below Oregon Health Authority guidelines.
The city says the treatment plant is working, the cyanotoxins are being removed and the water is safe to drink.
The city tests drinking waster seven days a week.
Cyanotoxins come from blue-green algae and can make people sick at high enough levels.
For the most up-to-date water quality information, go to https://www.cityofsalem.net/drinking-water