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The City of Portland, Oregon

Portland Water Bureau

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Water Bureau Finds Additional Cryptosporidium in Bull Run Water

Today, the Portland Water Bureau received results from ongoing monitoring of the Bull Run watershed, including one 50L (13 gallon) sample that was positive for Cryptosporidium, a potentially pathogenic microorganism. The positive sample was collected Monday, Feb. 13 and is the seventh positive sample out of 29 samples this year. The levels detected continue to be low, with one Cryptosporidium oocyst detected in this sample.

 With the possibility of further Cryptosporidium detections from the Bull Run, the Portland Water Bureau activated the groundwater wells from the Columbia South Shore Well Field on Monday Feb. 13.

“The health and safety of our customers is our top priority” said Portland Water Bureau Administrator Michael Stuhr “We will continue to work with our partners at Multnomah County Health Department and Oregon Health Authority while monitoring our drinking water source.”

At this time, there is no evidence of an increased public health risk as a result of this most recent detection. The bureau continues to recommend that people with severely weakened immune systems seek specific advice about drinking water from their health care providers. However, there is no need for the general public to take additional precautions.

“All identified cases of cryptosporidiosis, the disease caused by Cryptosporidium, are reported to state and county health officials” said Dr. Jennifer Vines, Deputy Health Officer, Multnomah County. “So far, the county’s ongoing disease surveillance has shown no unexplained increase in Cryptosporidium cases.”

Symptoms of cryptosporidiosis may include diarrhea, nausea, vomiting, stomach cramps, and fever. The symptoms can range from mild to severe. Cryptosporidiosis is not the only illness or condition that can cause these symptoms. These symptoms are common in the general population this time of year – up to 2 percent of the public can have similar symptoms on any given day (11,000 people in Portland). Health professionals recommend seeking medical advice if these symptoms persist for more than a few days.

The Portland Water Bureau currently does not treat for the parasite Cryptosporidium under a variance issued by the State of Oregon Health Authority in 2012. As required by the conditions of the variance, the bureau had been testing for Cryptosporidium at the source water intake twice a week. Since Jan. 8, after the initial detections, the bureau began monitoring at the source water intake at least four times per week. The bureau will continue to test the Bull Run for Cryptosporidium even while serving groundwater as the drinking water source. The results of this continued monitoring will be used to decide when to return to the Bull Run as our drinking water source.  

The Portland Water Bureau is continuing its investigation into the recent detections. While no specific source has been identified, scat from wildlife in the Bull Run that has been washed into the reservoirs are the most likely source of the Cryptosporidium detections. The bureau will continue to notify the public if any additional precautions are necessary. In the meantime, the bureau will continue operating our secondary groundwater source.

Additional information regarding the Portland Water Bureau’s treatment variance and answers to frequently asked questions are available at Customers with questions regarding water quality can call the Water Line at (503) 823-7525.


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