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The City of Portland, Oregon

Portland Water Bureau

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Cryptosporidium Detected In Bull Run Drinking Water

Oct 23 Media ReleaseThe Portland Water Bureau received results today that Cryptosporidium, a potentially disease-causing microorganism, was detected in a water sample collected Wednesday, Oct. 18. The detection was from a sample collected from the Bull Run Watershed intake as part of ongoing monitoring for Cryptosporidium. One oocyst was detected in the 10-liter sample. This detection follows other low-level detections from January through March and again in September of this year. The bureau continues to use the Bull Run as its primary source of drinking water.

About Cryptosporidium

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 Center for Disease Control (CDC), people with severely weakened immune systems are at risk for more serious disease. Symptoms may be more severe and could lead to serious or life-threatening illness. 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.

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.

No Increase in Cryptosporidium-Related Illness

Public health surveillance during and after a similar series of low-level detections from January through March of this year did not see an increase in Cryptosporidium-related illness. The general public is not advised to take additional precautions.

Water Sampling Results

The public and the media are encouraged to view all sampling results posted to the City’s website at

Water Quality Information

Customers with questions regarding water quality can call the Water Line at 503-823-7525.