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Water bureau does not know why parasite is repeatedly being found in Bull Run water for the firt time this year.

COURTESY PORTLAND WATER BUREAU - Black-tailed deer are among the many animals in the Bull Run Watershed who are known to carry and spread cryptosporidium.Portland Water Bureau officials do not know why cryptosporidium — a potentially deadly parasite — is being found this year in the Bull Run Reservoir that serves as the region's primary source of water.

Before this year, crypto, as the parasite is commonly called, had only been found twice in Bull Run water, once in 2002 and again in 2012. But it has been repeatedly been found in the water since January of this year, including in seven samples drawn in October.

"We cannot point to any data or evidence that says anything is different in the watershed," says Ann Levy, the bureau's environmental program manager in charge of the program that monitors for crypto.

There is no doubt that crypto has long existed in the Bull Run Watershed where the reservoir is located. It is found in animal feces and many different kinds of animals have always lived there, from small rodents to black bears. The Water Bureau has taken photos of many of them with wildlife trail cameras.

Crypto has been found in feces samples collected in the watershed since 2014, but not in reservoir water for many years until this January. Bureau officials believe rain is washing feces with crypto into the reservoir. But that has always happened, and officials do not know why the parasite was not found more often.

PORTLAND WATER BUREAU - Black bears are the only animals on the Portland Water Bureau's monitoring list that have not yet been found to be carrying cryptosporidium.

Checking scat for crypto

The 2012 variance approved by the Oregon Health Authority requires regular testing of Bull Run water, which produced the positive findings this year. It also requires Portland Water Bureau employees to collect animal feces in high-risk areas in the watershed and send them to a laboratory to be tested for crypto. The results of the Wildlife Scat Monitoring program — as it is formally called — have been documented each year in the Bull Run Treatment Variance Watershed Reports filed with the Health Authority. The cost is approximately $80,000 a year.

The monitoring program identifies the animals whose feces are to be collected and tested: American beavers, black-tailed deers, bobcats, black bears, Canadian geese, cougars, coyote, river otters, Roosevelt elk, snowshoe hares and small rodents, which include bushy-tailed woodrats, deer mice, mountain beavers, shrews and Townsend's chipmunks.

The number of each animal in the watershed varies greatly. According to a 2010 wildlife estimate by David Evans and Associates, they ranged from a low of six river otters to 35 black bears, 150 black-tailed deer and 204,000 small rodents.

The program also specifies how the samples will be collected.

"Scat samples will be visually inspected for freshness based on a sheen indicating high moisture content, remaining fraction of digestion byproducts, and pliability," it reads. "For most wildlife species, a scat sample will consist of one fecal deposit. For species such as rodents and hare that have small scat volumes, multiple fecal deposits collected from one area will be combined to make a composite sample. Each scat sample will be photo-documented and then collected aseptically. The scat samples will be packaged on ice and shipped overnight to the analyzing laboratory."

COURTESY PORTLAND WATER BUREAU - A bobcat in the Bull Run Watershed captured by a remote field camera.

Changing labs

According to the reports, no crypto was found in any of the samples in 2013. However, Water Bureau officials believe that was a fault of the lab being used, and they switched to another one. The next year, 15 percent of all samples tested positive for crypto. In 2015, the positive results increased to 21 percent. In 2016, they dropped to 17 percent.

The rates of crypto vary between animals by year. Black bears are the only animals that have never tested positive. The highest rate was 67 percent for cougars in 2016. Water Bureau officials say not enough samples are collected for the results to be scientifically accurate, however. They have ranged from 146 total samples in 2016 to 162 in 2015.

Bureau officials say inspections around the reservoir have not detected any more animals accessing it. And based on scat and camera monitoring, bureau officials do not believe the large mammal population has changed significantly in recent years. There is not enough data to know for sure about the small rodent population.

"No one is even able to make educated guesses" about why the positive crypto findings have increased, Levy says.

Concentrations minimal

Bureau officials note the amount of crypto found in samples is very low. For example, just one or two oocysts, a microscopic indicator of crypto, were found in each of the October samples. And officials say the strain of crypto was very unlikely to harm people. The most dangerous ones are found in the feces of humans and livestock, and both are barred by federal law from the watershed, except for Water Bureau employees.

Exposure to the most dangerous strains of crypto can cause cryptosporidiosis, a serious illness. Symptoms can include diarrhea, vomiting, fever and stomach pain. People with healthy immune systems recover without medical treatment. According to the Centers for Disease Control, people with severely weakened immune systems are most at risk for more serious dillness and even death.

Despite this year's findings, Water Bureau and Multnomah County health officials insist Bull Run water is still safe to drink. No increase in crypto-related illnesses has been reported this year, so far. Nevertheless, officials advise those with compromised immune systems to consult their doctors.

Examples of people with weakened immune systems include those with AIDS; those with inherited diseases that affect the immune system; and cancer and transplant patients who are taking certain immunosuppressive drugs.

But the findings have had serious consequences. Because Bull Run water has historically been so clean, in 2012 the Oregon Health Authority granted the city a variance from U.S. Environmental Protection Agency rules requiring municipal water providers to treat for crypto. Because of the findings, the Health Authority notified the city it was revoking the variance this month, prompting the City Council to approve a filtration plant that will physically remove crypto from the water before it reaches consumers. The plant will cost as much as $500 million and take up to 10 years to complete. Water rates will probably have to be raised to pay for it.

And if this year is any indication, water consumers will repeatedly learn of crypto being found in Bull Run water until the plant is completed.

In addition to the city of Portland, the Water Bureau provides Bull Run water to Burlington, the cities of Gresham, Sandy and Tualatin, and several water districts: Green Valley, GNR, Hideaway Hills, Lake Grove, Lorna Portland Water, Lusted, Palatine Hill, Pleasant Home, Raleigh, Rockwood, Skyview Acres, Tualatin Valley, Two Rivers, Valley View and West Slope.

To learn if your drinking water comes from Bull Run, contact your local drinking water provider.

The PWB is required to report all postive crypto findings. The public is encouraged to view all sampling results posted to the city's website at

Customers with questions regarding water quality can call the Water Line at 503-823-7525.

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