Oregon pushes for summer nitrate testing of Lower Umatilla Basin wells

At the outskirts of Boardman in Eastern Oregon’s Morrow County, water quality is determined by an invisible line.

On one side, a subdivision called Tuscany at Boardman is just within city limits, its manicured lawns and suburban-style homes fed by the city’s public water system. On the other side, about a mile south, is West Glen, an unincorporated community of modest trailers and manufactured homes served by private wells.

Zahira Guzman turned on the gravel road leading to her West Glen home after swimming in the Boardman public pool on a sweltering July day last week. Even before a water test three years ago revealed her home’s supply was contaminated with high levels of nitrates, Guzman, 37, never trusted her tap.

“Regardless of what the numbers say, I’m not drinking the water,” she said.

Nitrates in drinking water have been linked to cancer, thyroid diseases and infant illnesses. More than three decades after the state discovered concentrations that pose health risks in wells of the Lower Umatilla Basin, the Oregon Health Authority is still trying to determine the scope of pollution potentially affecting more than 3,000 households.

OHA is currently in the midst of a campaign to test the basin’s home wells through September, when health officials say nitrate levels tend to peak.

The campaign comes amid some residents’ ongoing lawsuit against agricultural operations they accuse of polluting groundwater, and an effort by Morrow County to connect some homes with contaminated wells to Boardman city water supplies. All these measures center on a community where many people, like Guzman, are already weary from the decades of unsafe water.

State data shows that only a fraction of basin households have tested for nitrates more than once, and many haven’t tested their water at all.

State push for testing

Operating under the slogan, “Ready to Well Test? Summer is best,” OHA plans to back up its campaign with in-person canvassing in August, going door-to-door for the first time since 2023.

OHA officials say additional rounds of testing are needed because nitrate levels often rise during the summer months, meaning some who previously tested under the federal limit could see higher levels under a new test. A recent study from the University of California, Davis suggests that extreme weather, like drought or heavy rain, can increase the risk of nitrates from fertilizers seeping into groundwater.

While nitrate pollution is less of a concern for municipal water systems that can filter the chemical associated with fertilizers out, domestic wells in unincorporated areas aren’t subject to the same regulatory standards.

Since 1990, Oregon testing has found that nitrates mostly associated with agricultural and industrial use were seeping through the soils of northern Morrow and western Umatilla counties, and into the region’s groundwater supply.

The state didn’t put together a comprehensive response until after Morrow County declared an emergency in 2022. OHA made a push to test basin households the following year, setting up free water deliveries to residents who tested above the federal limit of 10 milligrams per liter.

As of Monday, the state has tested 2,194 households out of an estimated 3,300. About a third of those households have tested above the federal limit, which means they are “needing bottled water at the very least,” said OHA Healthy Water Unit Manager Rob Benitez-Alicea Smith.

OHA recommends households in the basin test once per year, but state data shows only about one-third of households who have tested for nitrates have done so more than once.

Ana Piñeyro, the coordinator for OHA’s domestic well safety program, said the hope is to not only convince residents to retest but to capture some of the people who either refused testing or didn’t respond to OHA’s previous attempts to canvas the region three years ago.

“2023 [was] different than what it is today,” she said. “We see an increase of people coming back and saying, ‘I changed my mind, and now I want to test.’ That’s always a possibility.”

While a higher follow-up test could trigger water deliveries for some residents, OHA officials said the opposite wasn’t true. If a follow-up test revealed lower nitrate levels, the state will still continue to deliver water.

Not a revelation

Guzman said she’s tried to stay on top of the issue, but she’s also wary of how contentious the issue has gotten with some of her neighbors.

A group of basin residents, including some who live in West Glen, sued several farms and agricultural producers in 2024, accusing them of directly contributing to nitrate pollution. The lawsuit is still ongoing, although one of the defendants has already settled for $20.5 million.

Earlier this year, the state adopted new rules meant to require basin farms to track and manage their nitrate output, although critics argued that the state didn’t have enough resources to enforce them.

All of this is happening during an effort to connect some basin residents to municipal water sources, including a potential connection between West Glen and Boardman. Morrow County is soliciting engineering designs for a potential water connection but is still in talks with the City of Boardman over how to supply the water.

Guzman said she was open to having her home connected to Boardman’s water system. While some of her neighbors didn’t like the idea of paying Boardman for water, she considered the cost a wash when compared to paying for filters and bottled water to supplement the free water deliveries.

But further testing or even a city water connection isn’t going to change Guzman’s habits.

She said her late mother-in-law long suspected the water was unsafe and never drank from it.

“It had nothing to do with the nitrates,” Guzman said. “It’s just that she never liked the water. She’s like, ‘If I can afford to buy the bottled water, I’m just gonna buy it.’”

Guzman carried on that habit when she and her family moved into their home in 2021. When a test showed that her well water was well above the federal limit, Guzman considered the result more of a confirmation rather than a revelation.