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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 in northern Morrow and northwestern Umatilla counties. This is the area known as the Lower Umatilla Basin Groundwater Management Area (LUBGWMA). 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

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 October 31, 2024

Household Nitrate Test Results

Nitrate Range Morrow Umatilla Total
0 to 4.99 mg/L 235
733
968
5 to 9.99 mg/L 124
298
422
10 to 24.99 mg/L107
217
324
At or above 25 mg/L 125
 70
195
TOTALS 591
1318
1909

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

Nitrate Range Morrow Umatilla Total
10 to 24.99 mg/L 107
217
324
At or above 25 mg/L 125
70
195
TOTALS 232
287
519
Total high results as percent of all samples 39% 22% 27%

Water Treatment System Installations
____________________________________________________________________________________________________

Morrow Umatilla Total
95
104
199

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. 

Households Receiving Water Delivery

Morrow Umatilla Total
295
246
541



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