Published: Wednesday, January 11, 2012, 7:04 PM Updated: Thursday, January 12, 2012, 5:56 AM
Beth Slovic, The Oregonian
Testing found the potentially deadly parasite in two samples taken Dec. 30. In follow-up testing, cryptosporidium was found in a third sample taken Jan. 5 from a Bull Run tributary, the Portland Water Bureau announced Tuesday.
The watershed supplies much of the metro area’s drinking water.
A third test detected the microscopic parasite cryptosporidium in the Bull Run watershed, the source of much of the metro area’s drinking water. But city and state officials said it poses no public health threat.
“They’re not a threat to public health,” Portland Commissioner Randy Leonard, who oversees the Water Bureau, said of the samples. “They’re a demonstration of our stepped-up monitoring.”
But the results come at a bad time for the city, as officials await approval to skip building a $90 million plant to treat water for cryptosporidium. The city has fought for years for a variance to federal rules, arguing that Portland had not detected the parasite since 2002.
Just six weeks ago, city leaders celebrated after state regulators told the Water Bureau that it would probably grant the variance, with a final decision due Jan. 31.
On Wednesday, Leonard and David Shaff, the Water Bureau administrator, stressed that they don’t think the results will hurt that effort. Instead, Leonard argued that the sample showed the city had improved testing. “I think it actually strengthens it,” he said of the city’s case.
State regulators will consider the new information along with public comment, said Kathleen Vidoloff, a spokeswoman for the Oregon Health Authority. She added: “We don’t believe any of this has an imminent threat to public health.”
In a letter to state authorities this week, Shaff said the bureau will continue testing and investigating possible sources.
The first positive tests found one “oocyst” — a tiny seedlike structure for parasites — in each of two samples. The third found two oocysts in one sample.
Under rules of the proposed variance, good for 10 years, Portland would have to increase water monitoring after finding one sample with cryptosporidium. If a subsequent sample turned up more, the state could revoke the variance.
Cryptosporidium is found in animal feces and, if transmitted to humans, can cause gastrointestinal distress or death in already ill people. But not all forms harm humans.
In the Bull Run, heavy rain probably washed contamination into the water, Leonard said. A Texas laboratory will know this week whether it can pinpoint the origin, Shaff said. “We assume it’s wildlife of some sort,” he said.
— Beth Slovic
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