Among America's 75 biggest water providers, only one has recently exceeded federal standards for elevated lead levels in the drinking water of high-risk homes.

Portland.

And when Portland isn't surpassing that benchmark, it hovers just below - with current testing showing the greatest lead levels among all large cities.

The Rose City's poor position nationally is coming into sharp focus in the fallout over toxic lead levels exposed in Flint, Michigan. A newly released database, compiled by The Associated Press and analyzed by The Oregonian/OregonLive, reveals publicly that Portland's water system is an outlier, with lead levels in high-risk homes four times above those from similar cities.

Testing of high-risk houses is limited locally to those built between 1983 and 1985, although the threat encompasses homes constructed between 1970 and 1985. Because Portland sells water to several suburban communities, at-risk homes spread east, west and south of Portland proper.

Portland officials have long known that Bull Run water is corrosive and prone to releasing lead in such homes. But state regulators approved a unique deal in the 1990s that allowed Portland to get away with minimal chemical treatment.

Over the decades, Portland's reported lead levels have plummeted by two thirds but remain stubbornly high compared to other jurisdictions. It wasn't until 2003 that tests consistently began ducking under federal standards -- but only after officials changed their testing pool to include more suburban homes with fewer problems.

Today, city officials maintain Portland's water is perfectly safe, though a consultant is actively studying whether distribution pipes might also carry lead-tainted particles. And they say they're not troubled by comparisons to other cities.

"Comparing us to other systems isn't really what we're concerned about," said Scott Bradway, Portland's lead hazard reduction manager. "What we're concerned about is how our system is, and what the risk is for our population."

No amount of lead is considered safe. But, to be sure, Portland is not Flint.

Lead levels in Portland are exponentially below the toxic water found in Flint last year, and the risk here is far less widespread.

That's because Portland doesn't have the same kind of lead service lines that allowed corrosive water to suck metals indiscriminately into the homes of Flint residents. Here, the risk is greatest from in-home plumbing that features copper pipes connected with lead solder.

Portland provides water to nearly 1 million people, a quarter of Oregon's population, including residents served by Gresham, Tualatin and the Tualatin Valley Water District. The city's prestigious Bull Run water flows into about 271,000 single-family homes throughout the region.

Of those, nearly one in six - an estimated 43,000 homes built between 1970 and 1985 - are at the greatest risk for high-lead exposure, The Oregonian/OregonLive found. But Portland officials say they've conducted voluntary testing for only a tiny fraction.

Jeffrey Griffiths

, a Tufts University professor who chaired a U.S. Environmental Protection Agency drinking water committee, said Portland's results are concerning. He wouldn't recommend drinking water from high-risk homes at Portland's reported levels.

"Give me a break," he said. "And I certainly wouldn't be using that water to be making baby formula and giving it to my infant with a developing brain."

Lead is a toxic metal that builds up in blood when ingested. It's especially dangerous for children younger than 6 and pregnant women. Lead poisoning can lead to miscarriage or developmental problems in children.

Federal regulators require water providers to keep lead levels at or below 15 parts per billion, as measured through samples collected at specific homes throughout the system. If samples from at least 10 percent of those high-risk homes exceed that level, water systems must notify the public or take steps to reduce corrosion.

Portland has exceeded that standard 10 times, most recently in fall 2013 with results of 15.9 parts per billion. In the past four testing cycles, it's held just below, including the latest results from fall 2015 of 14.1.

Seattle last tested at 3.5 parts per billion. Oakland reported 3.

"Oregon touts itself as some environmental mecca. Well congratulations, you're pretty near the top of the list for lead in water, and you've been there for more than a decade now," said Marc Edwards, a Virginia Tech professor who helped spotlight problems in Flint.

"And your water company seems perfectly content, and not the least bit embarrassed," he added. "And to be there with no lead pipes. That's not setting the bar very high."

A novel approach

Portland's water, from the Bull Run watershed 26 miles east of downtown, is "pure" and "clear," according to the city.

Tips to reduce lead exposure

* Get a free lead-testing kit by calling 503-988-4000 or

filling out an online request form

* Run water for 30 seconds to 2 minutes

* Don't use water from the hot-water tap for drinking or cooking

* Buy a water filter that reduces lead

* Clean the faucet aerator

* Replace the faucet

SOURCE: Portland Water Bureau

And it's injected with very few additives, a philosophy embodied by voters' long-standing rejection of fluoride treatments.

The water is also considered "soft," making it corrosive.

Back in 1991, federal authorities realized they needed to lower lead and copper in drinking water across America. In the following two years, Portland's samples from high-risk homes came back with plainly high results: 44 and 53 parts per billion.

The EPA wanted Portland to add an assortment of chemicals to Portland's water. The most obvious solution was to add sodium hydroxide, carbon dioxide and soda ash, chemicals that would help reduce pipe corrosion that releases lead.

But city leaders pushed back, saying such steps would "exceed the benefit to the community" because only some homes had lead plumbing components.

In August 1995, officials pitched "minimal corrosion control" combined with education and testing programs to reach at-risk homes, with a special focus not on water but lead-based paint. They proposed adding only sodium hydroxide to water, estimated at the time to save about $10 million over 10 years compared to more treatment.

State officials, with oversight responsibility for federal lead regulations, signed off.

Dave Leland, Oregon's drinking water manager, said he's not aware of a similar agreement in any other jurisdiction.

"It's a little bit novel, but we thought it met the intent," Leland said. "To be fair, EPA has been uneasy about that. They've been periodically uneasy."

Portland began adding sodium hydroxide in 1997. For 11/2 years, things looked good as results came back below federal action levels. But success was short-lived.

Diluting the numbers

Starting in fall 1998, results from six of nine testing cycles came back too high. The EPA again began pressing for action.

Portland added more sodium hydroxide to reduce corrosion. But city officials also made another change: They dramatically altered the sample of homes tested.

Officials cut more than half of the worst-performing homes, according to a 2004 Washington Post investigation, and replaced them with suburban locations with much lower lead levels.

In the years since, Portland has exceeded the federal action level just twice.

Bradway, Portland's water lead hazard reduction manager, said altering the pool of test homes was not an effort to game the system. Homes selected for removal were picked at random, he said, and officials added suburban homes to better represent the distribution of at-risk properties rather than total customers served.

But the location of homes can make a huge difference, records obtained by The Oregonian/OregonLive show.

Some of Portland's suburban wholesale customers mix Bull Run water with other sources or add chemicals of their own. As a result, the prevalence of lead varies by jurisdiction.

Portland is required to collect at least 100 samples from area homes. At least 36 of those are collected from customers of the Tualatin Valley Water District, which serves unincorporated Washington County.

Just 28 samples must come from Portland, 18 from Gresham, and the rest from the remaining suburban water providers.

Tualatin Valley helps the whole system look better.

Between 2003 and 2013, records show, officials collected 879 samples from homes in the water district. Of those, just 2 percent came back above 15 parts per billion.

But for Portland, which had the second-most samples, the exceedance rate was three times higher. And for Gresham, it was six times higher.

In any testing cycle, system-wide results could tip past the federal threshold with high numbers from just a couple of additional homes.

Mark Knudson, Tualatin Valley's chief executive, recently suggested that the district - which also uses water from Hagg Lake - consider separate testing and treatment requirements for lead because of the differing results.

"It does look like we have a tendency to drive down or dilute the results" for everyone else, he said.

Reducing lead

Changes are on the horizon.

In the wake of Flint - where Edwards, the Virginia Tech professor, found one water sample with lead at 13,000 parts per billion - federal authorities are now promising heightened scrutiny.

As a result, Portland recently met with federal and state regulators to discuss its efforts. Portland is in the process of disconnecting its open-air reservoirs, and officials are studying what those changes may mean for corrosion control.

Already, outside consultants are taking a hard look. While officials have regularly blamed in-home plumbing as the sole source of lead, consultants want to rule out that no lead is coming from the distribution system, according to records.

They've also questioned whether lead from decades-old city pipes has been absorbed into the coating of service lines, and whether disruptions in the flow of water may dislodge lead-laced particles - an issue that could affect more than just high-risk homes.

"Transport of lead by possibly iron or manganese is suspected to be significant in the water system because of the random patters of high lead" found in mapping, an October 2015 report reads.

City officials are downplaying that hypothesis.

"The report outlines theories about potential lead exposure that are being investigated by the study, not findings about our water system," Jaymee Cuti, a Water Bureau spokeswoman, said in a statement.

Full results won't be ready until later this year. Portland Commissioner Nick Fish, who oversees the Water Bureau, said it's premature to consider changing treatment options until it's complete.

"As always, important decisions about our drinking water will be driven by science and by Portland values," Fish said in a statement.

The EPA, meanwhile, praised Portland's long-term approach as "thoughtful." But the agency said it looks forward to Portland decommissioning its open-air reservoirs at Washington Park, which should improve its ability to minimize the corrosiveness of water.

"EPA now expects" that Portland can "maximize health protections by reducing lead at consumers' taps to levels as low as feasible, which is a priority for EPA," the agency said in a statement.

Leland, the state water official, said he's always suspected Portland would have the highest reported lead levels among big cities.

But Leland said it was the right decision to launch a broader lead-reduction program. Confirmed cases of children with high blood levels have dropped in Multnomah County, statistics show, although so have numbers statewide.

"We have not changed our minds," Leland said.

But in the nearly two decades since Portland resisted more expansive treatment, thousands of residents in high-risk homes have been exposed to potentially high lead levels.

Take Jerry Woodcock's house in Portland's Pleasant Valley neighborhood.

Results from Woodcock's home, built in 1984, are included in regional compliance numbers. Woodcock said he remembers receiving results from the Water Bureau but didn't pay them much mind.

Lead levels in Woodcock's home have exceeded 15 parts per billion in half of his tests since 2010, records show. Two of those topped 32 parts per billion.

He's tried to follow the city's advice and let his water run each morning, although he admits he's not always so diligent.

"You see a few of these things and they're below, or they're a hair above, and you're not particularly alarmed," he said of the city's notices. "But when you're giving me these high numbers, it's definitely more cause for concern. Kind of a wake-up call."

Correction: An earlier version of this story stated that reported lead levels had dropped by one third. They've dropped by about two thirds.

-- Brad Schmidt

Reporter Fedor Zarkhin contributed to this report

bschmidt@oregonian.com

503-294-7628

@cityhallwatch