July 16, 2026

Media Contact: Jonathan Modie, PHD.Communications@oha.oregon.gov 

Concentrations of nitrate can be higher in domestic wells during warmer months, OHA officials say

PORTLAND, Ore.—Oregon Health Authority (OHA) is encouraging residents of the Lower Umatilla Basin Groundwater Management Area (LUBGWMA) to test their well water for nitrate this summer, a time of the year when concentrations of the chemical can be higher.

OHA is kicking off a summer education and testing campaign with the slogan “Ready to Well Test? Summer is best!” that reminds domestic well users in the LUBGWMA about the importance of testing between July and September. Limited nitrate data OHA has collected in the area since March 2023 show that levels of nitrate increase during summer months.

The LUBGWMA is an area spanning northern Morrow County and northwestern Umatilla County designated by the state due to high nitrate in groundwater that supplies domestic wells.

OHA and county public health staff and volunteers will go door to door in LUBGWMA communities in August and September to offer free well testing. Households with a laboratory nitrate test result above 10 milligrams per liter (mg/L) can receive free water delivery. For households whose well water tests higher than 10 mg/L but below 25 mg/L, OHA will pay for installation and maintenance of one in-home reverse-osmosis system certified to reduce nitrate levels to safe for drinking (treatment systems are not certified to remove nitrate at levels above 25 mg/L).

More information about the locations, dates, and times for door-to-door canvassing in the area will be provided closer to the August canvassing period.

Nitrate in well water is a potential health hazard, and levels above 10 mg/L can be dangerous for human consumption. Pregnant people and babies face the greatest risk. Retesting households with well water close to the health action level of 10 mg/L of nitrate is especially important because nitrate levels can fluctuate during different seasons of the year.

“The goal of the OHA Domestic Well Safety Program is to determine public health risk from nitrate exposure in domestic wells, so first-time samples and seasonal re-samples of well water are best collected during the period most likely to reflect a worst-case scenario,” said Ana Piñeyro, coordinator of the Domestic Well Safety Program in OHA’s Environmental Public Health Section.

Anyone who lives in the LUBGWMA can get a free nitrate laboratory analysis of their well water by visiting the website testmywell.oregon.gov (in Spanish at pruebadepozo.oregon.gov) or emailing Domestic.Wells@odhsoha.oregon.gov. They can also call the OHA Domestic Well Safety Program at 541-952-9254.

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