Portlanders got a small scare this week after the city’s water utility announced it had picked up trace amounts of the parasite Cryptosporidium in Bull Run drinking water. Officials were quick to add that the tap is still considered safe for most people and that customers do not need to change their routines, while anyone with a severely weakened immune system is urged to check in with their health care provider about whether to keep drinking tap water.
In an April 3 Facebook post, the Portland Water Bureau walked through late-March test results from its Bull Run intake. A sample collected March 30 showed two Cryptosporidium oocysts, and the March 31 sample showed one oocyst. The bureau said low-level detections like these may pop up from time to time during the rainy season as monitoring ramps up, according to the Portland Water Bureau.
What the tests showed
To keep tabs on the Bull Run supply, the bureau filters about 50 liters of raw water for each daily sample and logs the results in a public table that tracks dates and oocyst counts. That running log shows several low-level positives this month and notes that the utility has been detecting Cryptosporidium off and on since 2017, according to the Portland Water Bureau.
Health risks and who should be cautious
Cryptosporidium is a microscopic parasite that can cause cryptosporidiosis, a diarrheal illness that tends to be unpleasant but short-lived for otherwise healthy people. The calculus changes for those with compromised immune systems, where the infection can become severe or drag on much longer.
The Centers for Disease Control and Prevention advises higher-risk groups - including organ-transplant recipients, people living with HIV/AIDS, and patients undergoing chemotherapy - to talk with their health care providers about their specific risk and, if they are worried, to consider bottled or boiled water, according to the CDC.
Why filtration matters
To deal with Cryptosporidium more decisively, Portland is in the middle of building a full-scale filtration plant for Bull Run water. The city’s current schedule has filtration coming online in September 2029 to comply with state and federal requirements. The price tag for the project has climbed in recent months, and city officials have told reporters they are asking the Oregon Health Authority for extra time to meet earlier deadlines, according to OPB.
Where to get updates
The Portland Water Bureau says it posts all sampling data online and will alert the media and the public right away if any test suggests a genuine public health concern. Customers with questions can call the Water Quality Line at 503-823-7525. The bureau’s latest notice and the full sampling log are available from the Portland Water Bureau.
