Since 2017, the Portland Water Bureau has detected low levels of Cryptosporidium from routine monitoring of source water. The Portland Water Bureau received results from ongoing monitoring from the Bull Run Watershed intake for Cryptosporidium, a potentially disease-causing microorganism. Two Cryptosporidium oocysts were detected in the 50-liters collected on Nov. 14. From Nov. 15 to Nov. 17 the Portland Water Bureau changed the drinking water source from the Bull Run source to groundwater from the Columbia South Shore Well Field due to storm damage to the Lusted Hill treatment facility. On Nov. 17, after transitioning back to the Bull Run source, another 50-liters were sampled with 4 Cryptosporidium oocysts detected. Prior to these detections, Cryptosporidium was last detected from the Bull Run Watershed intake on October 17, 2021.
The Bull Run watershed is Portland’s primary source of drinking water. The Portland Water Bureau does not currently treat for Cryptosporidium, but is required to do so under drinking water regulations. Portland is working to install filtration by September 2027 under a compliance schedule with the Oregon Health Authority. In the meantime, Portland Water Bureau is implementing interim measures such as watershed protection and additional monitoring to protect public health. Consultation with public health officials has concluded that at this time, customers do not need to take any 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. 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.
The Environmental Protection Agency 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. The Portland Water Bureau and Burlington, City of Gresham, City of Sandy, City of Tualatin, Green Valley, GNR, Hideaway Hills, Lake Grove, Lorna Domestic Water, Lusted, Palatine Hill, Pleasant Home, Raleigh, Rockwood, Skyview Acres, Tualatin Valley, Two Rivers, Valley View and West Slope Water Districts receive all or part of their drinking water supply from Bull Run. To learn if your drinking water comes from Bull Run, please contact your local drinking water provider.
The public and the media are encouraged to view all sampling results posted to the City’s website at portland.gov/water/cryptoresults. The bureau will notify the media and public immediately should further test results indicate a risk to public health and precautions are necessary.
Customers with questions regarding water quality can call the Water Quality Line at 503-823-7525.
About the Portland Water Bureau
The Portland Water Bureau serves water to almost a million people in the Portland area. Portland’s water system includes two great water sources, 53 tanks and reservoirs, and 2,200 miles of pipes. With 600 employees working on everything from water treatment to customer service, the Water Bureau is committed to serving excellent water every minute of every day.