Several detections of the parasite cryptosporidium in Portland's main water supply earlier this year could end up costing the city hundreds of millions of dollars.
The Portland Water Bureau , meaning the city must now start treating its water for the parasite.
Officials found crypto oocysts in water from Portland's Bull Run watershed 19 times earlier this year, which resulted in the city briefly switching to a backup supply in February.
It was the first time Portland had found the potentially dangerous parasite in its water since 2011. While there are many types of cryptosporidium and not all are known to make people sick, federal rules about preventing the organism do not distinguish between these types.
The city resumed using Bull Run water, which serves almost 1 million Oregonians, in March. That was after the bureau and the Oregon Health Authority determined the water did not pose a significant health risk.
"There has not been a detection since mid-March," Water Bureau spokeswoman Nicole Adams told OPB. "Even though there is not a public health risk, the variance is being revoked by OHA."
The reason Portland can no longer use Bull Run water as it has in the past is because those 19 detections pushed the city out of compliance with testing rules set forth by the state in its variance agreement.
In 2006, the U.S. Environmental Protection Agency rolled out more aggressive rules for treating cryptosporidium in water sources.
OHA allowed Portland an exemption to those rules in 2012 because the city demonstrated through hundreds of tests it had almost no crypto in its water.
But, under the agreement, Portland could only keep its variance if it routinely showed less than 0.075 oocysts per 1,000 liters of water each year — the same level a treated system would provide. By March of this year, the city had found 12 oocysts in 2,200 sampled liters of water.
Adams said that by her math "we would have to max out every water testing lab in the country" to get back in compliance with the variance this year.
Though tests have regularly shown Portland's water is safe to drink and there have not been recent detections of the parasite, being out of compliance with the variance is likely going to carry a hefty financial cost for Bull Run water users.
In 2009, before OHA granted a variance, city workers determined the cheapest fix for crypto would be to build an ultraviolet light plant at a cost of $100 million. The most expensive solution at the time would have been a filtration plant at a cost of $385 million.
Now that Portland cannot meet the terms of its variance, the city has little choice but to build a treatment facility.
Adams said the Water Bureau is in the process of reviewing and updating those 2009 plans, so it is unclear what a solution would cost now.
However, she said, Portland area water users won't face higher bills immediately as a result of losing the variance.
"There won’t be rate hikes this year," Adams said.
Before that happens, the Portland City Council will have to approve a water treatment plan to replace the OHA variance.
The Health Authority stipulates in its letter to the Water Bureau that the new plan must be in place by Sept. 22.
In the meantime, the city will continue to test the water on a weekly basis for cryptosporidium.