Since 2017, the Portland Water Bureau has detected low levels of Cryptosporidium, a potentially disease-causing microorganism, from routine monitoring of the Bull Run Watershed intake. In the 50-liters sampled daily, between Sunday, March 29 and Wednesday, April 1, one Cryptosporidium oocyst was detected in the sample collected on March 31. Cryptosporidium was not detected in the samples collected on March 29, March 30 or April 1. Prior to these detections, Cryptosporidium was last detected from the Bull Run Watershed intake on March 16, 2020.
The Bull Run watershed is Portland’s primary source of drinking water. The Portland Water Bureau does not currently treat for Cryptosporidium, but is working to install filtration by September 2027 under a compliance schedule with Oregon Health Authority. According to the Bureau, after consulting with public health officials, customers do not need to take additional precautions.
Exposure to Cryptosporidium can cause cryptosporidiosis, a serious illness. Symptoms can include diarrhea, vomiting, fever and stomach pain. People with healthy immune systems recover without medical treatment. According to the Centers for Disease Control and Prevention (CDC), people with severely weakened immune systems are at risk for more serious disease. Examples of people with weakened immune systems include those with AIDS; those with inherited diseases that affect the immune system; and cancer and transplant patients who are taking certain immunosuppressive drugs.
The Environmental Protection Agency (EPA) has estimated that a small percentage of the population could experience gastro-intestinal illness from Cryptosporidium and advises that customers who are immunocompromised and receive their drinking water from the Bull Run Watershed consult with their healthcare professional about the safety of drinking the tap water. To learn if your drinking water comes from Bull Run, please contact your local drinking water provider.
For more information about Cryptosporidium in drinking water for immunocompromised individuals, view the Bureau's informational brochure.
Customers with questions regarding water quality can call the Water Quality Line at 503-823-7525.