Skip to main content

Oregon State Flag An official website of the State of Oregon »

Oregon Health Authority

Nitrate testing, treatment, and water delivery for the Lower Umatilla Basin

The Oregon Health Authority (OHA) is working with its partners the Oregon Department of Human Services, Morrow County Public Health Department, Umatilla County Health Department, and community based organizations to provide free safe water services to households impacted by high nitrate levels in northern Morrow and northwestern Umatilla counties. This is the area known as the Lower Umatilla Basin Groundwater Management Area (LUBGWMA). Nitrate levels at or over 10 miligrams per liter (mg/L) can cause serious health issues, especially for pregnant people and babies.

What is on this page?

The maps below show the results of laboratory tests for nitrate in well water. The tables lower on the page provide the same information by the numbers, along with tables listing the number of households that have had water treatment systems installed, and households receiving bottled water deliveries.

For more information about the data that OHA is collecting related to domestic well testing in the Lower Umatilla Basin, please read this memo from Gabriela Goldfarb, OHA’s Environmental Public Health Section Manager.

All nitrate test results

All Nitrate test reults

Nitrate test results at or above 10 mg/L (high levels)

Nitrate test results at or above 10 mg/L

Nitrate test results 5 mg/L to 9.99 mg/L

Nitrate test reults 5 mg/L to 9.99 mg/L

Nitrate test results below 5 mg/L

Nitrate test reults below 5 mg/L  

Summary tables updated January 31, 2025

Household Nitrate Test Results

Nitrate Range Morrow Umatilla Total
0 to 4.99 mg/L
242
743
985
5 to 9.99 mg/L
133
288
421
10 to 24.99 mg/L
127
239
366
At or above 25 mg/L
144
 73
217
TOTALS 646
1343
1989

Households with Nitrate Test Results At or Above 10 mg/L

Nitrate Range Morrow Umatilla Total
10 to 24.99 mg/L 127
239
366
At or above 25 mg/L 144
73
217
TOTALS 271
312
583
Total high results as percent of all samples 42% 23% 29%

Water Treatment System Installations
____________________________________________________________________________________________________

Morrow Umatilla Total
103
117
220

Additional Notes
  • The number of water treatment systems listed above includes households that got a full water test from OHA and those that got a nitrate test from the Morrow County Health Department in 2022. The maps and data tables above that show nitrate test results only include the tests done by OHA. This means that the number of treatment systems listed may be different from the number of houesholds that are eligible for treatment through OHA testing. These are households with nitrate levels between 10 and 25 milligrams per liter of water. 
  • UPDATE February 5, 2025: We discovered a duplication in our counts which reduced the number of systems installed in Umatilla County from 120 (December 2024) to 117 (January 2025).

Households Receiving Water Delivery

Morrow Umatilla Total
298
255
553

Latest news