Potentially deadly parasite found in Bull Run water again
A potentially deadly microorganism has been found again in the Bull Run reservoir that provides water to Portland and much of the region.
According to findings released late Friday afternoon by the Porland Water Bureau, cryptosporidium was detected in samples collected on Tuesday, Feb. 7, and Wednesday, Feb. 8. They are the fifth and sixth positive samples this year.
"All identified cases of cryptosporidiosis, the disease caused by cryptosporidium, are reported to state and county health officials" said Multnomah County Deputy Health Officer Dr. Jennifer Vines. "So far, the county's ongoing disease surveillance has shown no unexplained increase in cryptosporidium cases."
Portland-area residents and businesses have already paid a high price for the city of Portland to comply with a U.S. Environmental Protection Agency rule intended to keep a potentially deadly microorganism and other contaminants out of the region's water supply.
And it hasn't completely worked.
The parasite cryptosporidium has been found four times since the start of the year in the Bull Run Reservoir — the primary water source for Portland and a number of surrounding communities. Although it is too soon to predict what will happen, the Oregon Health Authority has the power to require the Portland Water Bureau to build a treatment plant at the reservoir to kill the potentially dangerous parasite.
According to OHA spokesman Tony Andersen, the state agency is allowing Portland to continue collecting and testing Bull Run water for crypto — as it is commonly called — under a variance to the Environmental Protection Agency's rule granted in 2012.
But Andersen says the health authority also is "working through a range of options for the future" in case the results exceed the allowable limit. That is 0.075 or more "oocysts" per thousand liters of tested water at the end of current one-year monitoring period. An oocsyst is a miscroscopic structure that proves the existence of the parasite.
If that limit is exceeded, OHA will revoke the variance and set a schedule for the PWB to install the EPA-required treatment.
The last time the bureau studied building an ultraviolent (UV) light treatment plant to kill crypto in the reservoir was in 2012, when the cost was estimated at $70 million. The cost would be paid by Portland Water Bureau ratepayers, as with the recent cost to disconnect the open reservoirs at Mount Tabor and Washington parks. That was done to meet EPA requirments to keep crypto, other microogranisms, viruses, and other contaminants out of public water supply systems.
Water Bureau officials say the results so far are below the health authority's limit, although the final determination will not be made until the end of the year. They also argue there is no proof anyone has ever gotten sick from Bull Run water. At the same time, the officals are advising "people with severely weakened immune systems to seek specific advice about drinking water from their health care providers."
That is because crypto can cause cryptosporidiosis, a respiratory and gastrointestinal illness. It can affect anyone, but is especially dangerous to immunodeficient people. An outbreak killed 104 people and sickened around 400,000 others in Milwaukee, Wisconsin, in 1993, helping to prompt the EPA to adopt its LT2 rule.
Crypto is spread through animal feces. Because there are no domesticated animals in the Bull Run watershed, city Water Quality Team Manager Yone Akagi says wild animals are most likely the source of crypto found in the reservoir samples.
Akagi does not know why crypto has suddenly been detected in the reservoir. It has not been previously found in the testing required by the health authority since the variance was granted five years ago. One possibility is the heavy storms that have hit the region this year, Akagi says. They may have washed more contaminated soil than usual into the reservoir.
Previously, positive results were found in samples collected on Jan. 2, 3, and 25 and on Feb. 1.
Whatever the cause, the positive results already have required the Water Bureau to accelerate its monitoring schedule, increasing the amount of water collected and tested from 50 liters twice a week to 250 liters four times a week. It can be argued that the more-frequent and larger collections are theoretically increasing the chances more crypto will be found in the samples.
But for now, according to Andersen at the health authority, as the Water Bureau "continues to meet the variance conditions and OHA determines that there is a low public health risk (as is the case with these previous results), the variance will remain in place."