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Today, the Portland Water Bureau received results that Cryptosporidium, a potentially pathogenic microorganism, was detected in a water sample collected Wednesday, January 25, from the Bull Run watershed, which provides drinking water to Portland and neighboring communities. The lab results show that one individual Cryptosporidium oocyst was present in a 50-liter (~13 gallons) sample of water.
At this time, we do not believe there is any increased public health risk as a result of the current detection. The general public is not being asked to take any special precautions. We continue to recommend that people with severely weakened immune systems seek specific advice about drinking water from their health care provider.
The Portland Water Bureau currently does not treat for the parasite Cryptosporidium because of a variance issued by the State of Oregon Health Authority (OHA) in 2012. Instead, the Portland Water Bureau is required to conduct routine monitoring for Cryptosporidium and notify the public of any detections.
This detection at the intake is the third detection this month. January 2nd was the first detection since the Portland Water Bureau began operation under the variance in April 2012. Prior to that, the last time Cryptosporidium was detected was December, 2011, when a single oocyst was also detected.
As required by the conditions of the variance, the Portland Water Bureau had been testing for Cryptosporidium at the source water intake twice a week. Since January 8th, the Portland Water Bureau began monitoring at the source water intake at least four times per week for one year to demonstrate whether the Cryptosporidium concentration in the source water is less than 0.075 oocysts per 1,000 liters.
“While these detections do not indicate an increased public health-risk, we are taking them very seriously.” said Water Bureau Administrator Mike Stuhr. “Public safety is the Water Bureau’s top priority. We will continue increased monitoring at the drinking water
source, and continue close coordination with health officials at all levels to continue to protect public health.”
The City continues to consult with the Multnomah County Health Department and OHA. Public health officials have determined that no special precautions for Portland’s drinking water are currently necessary, aside from the increased monitoring and testing efforts currently underway. Portland-area health departments will also increase public health monitoring for indications of an increase in Cryptosporidium related illness that could be related to drinking water.
“Historically, we cannot find any evidence of a cryptosporidiosis outbreak tied to drinking Bull Run water.” said Multnomah County Deputy Health Officer Dr. Jennifer Vines. The county’s ongoing disease surveillance has shown no unexplained increase in Cryptosporidium cases.
The Water Bureau is continuing a thorough investigation. Wildlife found in the Bull Run are the most likely source of the Cryptosporidium detections, however no specific source has been identified. The Water Bureau will notify the public if any additional precautions are necessary.
Additional information regarding Water Bureau’s treatment variance is available at www.portlandoregon.gov/water/lt2treatmentvariance. Customers with questions regarding water quality can call the Water Line at (503) 823-7525.