The Portland Water Bureau will have to spend upward of $90 million to construct a water treatment plant the state previously excused the city from building after finding excessive levels of the cryptosporidium parasite between January and March.

The city knew that it would exceed state limits on the parasite as early as March, a fact it omitted from a March 22 press release reassuring the public. The city told the state in a March 8 letter that it expected to exceed the state's threshold for cryptosporidium in drinking water by the end of this year.

In February, water bureau Commissioner Nick Fish admonished The Oregonian/OregonLive that it was "irresponsible" to ask whether the city should start considering building a treatment facility.

"It is very unlikely that that is going to happen," Fish told The Oregonian/OregonLive, a month before the bureau informed the state of its inability to meet the requirements exempting the city from water treatment.

"The point I was making—and I stand by it—is we're the regulated and not the regulator," Fish told The Oregonian/OregonLive Thursday. "I thought it was irresponsible to get ahead of the process and start speculating."

The water bureau found the cryptosporidium parasite in the area's drinking water supply in at least 14 tests in 2017, more than they have in the last decade. Of those, twelve occurred in January and February.

The Portland water bureau provides drinking water from Oregon's Bull Run watershed, a source that Fish and others have touted as pristine and the magnet for Portland's booming local beer industry.

In 2012, the Oregon Health Authority gave Portland an exemption from federal rules requiring cities to treat their drinking water for parasites. It did so on the condition that regular tests for the parasite found less than .075 of an oocyst—a microscopic hard parasite structure—per 1,000 liters on average each year.

The state agency informed the Portland Water Bureau in a May 19 letter that it will revoke that exemption on September 22 or when the health authority signs a compliance schedule and agreement with the city, whichever comes first. The Portland Tribune first reported the state's decision to revoke Portland's exemption.

The water bureau detected 12 oocysts of the parasite in 2,200 liters of water from January 1 to March 8, according to the state's letter. On March 8, the water bureau notified the Oregon Health Authority that it was "not feasible" for the bureau to conduct further tests on a sufficient quantity of water to demonstrate that its annual average parasite concentration falls below the allowable threshold.

In response, the state wrote: "Without a cryptosporidium treatment variance, (the water bureau) is required to fully comply with the cryptosporidium treatment requirements."

This means building a treatment plant.

Getting one built and operating is expected to take about five years. In the meantime the bureau plans to continue to provide customers with water from the Bull Run watershed that was the source of the cryptosporidium.

County and state health officials and the city determined that the water is still safe to drink, they said. The state's epidemiologist and the Centers for Disease Control and Prevention also deemed the water safe, Oregon Health Authority spokesman Tony Andersen said.

The water bureau tested the genetic makeup of two of the positive samples and found they came from rodents and other unidentified wildlife.

Cryptosporidium found in animal feces rarely sicken humans, who usually only get ill from the microorganism if it comes from another human, said Multnomah County Health Officer Paul Lewis. There were fewer cases of illness caused by cryptosporidium this year than average, Lewis said.

Planning for the treatment plant will launch in the near term. By August 11, the city must provide the state with a description of the treatment technology it intends to use. The water bureau could either build an ultraviolet treatment plant, projected in bureau planning documents to cost at least $89 million, or a $300 million filtration treatment system that would filter out sediment in addition to microorganisms.

The city must also submit a schedule showing when the treatment can be in place "as soon as practically possible." This plan must include specific dates and identify when "water that fully meets all requirements will be served to the public," the state's letter said.

Fish said he directed water bureau officials to hold a work session with the City Council in the end of June to explain why cryptosporidium detections increased and lay out the options for constructing a treatment plant.

Bureau director Mike Stuhr said he can't scientifically say why instances of the parasite increased, but noted that the area had a "terribly unseasonable rainfall."

Fish said he will try to find consensus within the council on the best treatment method going forward. An ultraviolet plant, he said, is less expensive but does less, while a filtration treatment plant could help the city address future issues as regulations get stricter.

"It's too early for me to advocate" for the best option, Fish said. "Last time, cost became a big part of the discussion...The least-cost option is going to carry a lot of weight at council."

Fish said this will not impact the charges to water users set in the coming year's budget. He said the water bureau might use rate stabilization dollars it has set aside over the years to offset any increased costs.

Mayoral spokesman Michael Cox confirmed the treatment facility construction costs will not affect the coming year's budget.

"In terms of future budgets, we don't want to get ahead of the work session," Cox wrote in a text to The Oregonian/OregonLive. "The council will decide this as a body."

The water bureau is still serving Portlanders Bull Run water. It served only groundwater from February 13 to March 15 after finding cryptosporidium in six tests. The bureau found cryptosporidium seven more times before it started decided to again serve Bull Run water.

"We had a couple of small hits that appeared to be tapering off," Stuhr said.

Even during the high-discovery period in winter, Lewis said concerns for public illness remained low.

Fish said the council will decide the details of how to finance the treatment plant.

--Jessica Floum

503-221-8306