The Portland Water Bureau reported detecting Cryptosporidium in the Bull Run Watershed, the city’s main drinking water source. Between Sunday and Tuesday, low levels were found: two oocysts on Sunday and one each on Monday and Tuesday. No Cryptosporidium was detected on Wednesday. These findings follow an earlier detection on November 19, according to the Bureau.
According to the City of Portland, Cryptosporidium can cause cryptosporidiosis, with symptoms including diarrhea, vomiting, and fever. The Water Bureau does not yet treat the water for this pathogen, but plans to install filtration by September 30, 2027, to meet drinking water regulations. In the meantime, interim measures such as enhanced watershed protection and monitoring are in place. Health officials say no additional precautions are needed for consumers.
Monitoring is especially important for people with compromised immune systems, such as those with AIDS or cancer patients on certain medications, as they are more susceptible to severe illness from Cryptosporidium. The EPA advises at-risk customers to consult healthcare professionals about their tap water. Affected districts, including Tualatin Valley, Lake Grove, and West Slope, can be confirmed with local water providers.
The Portland Water Bureau posts all Cryptosporidium monitoring results on the City’s website. If future tests indicate a public health risk, the Bureau will notify residents immediately. Customers with questions about water quality can call 503-823-7525.
