DEQ Lab releases groundwater quality report for Oregon’s Walla Walla Basin

A new report from DEQ’s Laboratory shows water quality data for groundwater aquifers in the Walla Walla River Basin in Oregon.

The basin straddles northeast Oregon and southeast Washington. DEQ sampled water from 100 residential and agricultural wells on the Oregon side and detected 41 different chemicals in the water, including pesticides, metals, nutrients and bacteria. Some of these chemicals, such as low levels of minerals, naturally exist within water, and others are contaminants.

Most contaminants detected in this study were at levels below EPA drinking water standards, but nitrates, lead and bacteria exceeded health standards in some wells.

DEQ shared individual water quality results with the well owners where the agency took samples, along with educational materials about EPA drinking water standards and well maintenance. Groundwater contaminants in drinking water wells could indicate that wells need repair or that there are nearby sources of contamination, such as failing septic systems or pesticides, fertilizers, manure or household chemicals applied to the land.

Oregon does not have water quality regulations for private wells. Homeowners are responsible for maintaining their wells and ensuring the water is safe to drink. Oregon only requires that domestic wells are tested for nitrate, arsenic and bacteria during real estate transactions.

“Many people rely on groundwater for domestic, industrial and agricultural reasons. We want to get a baseline understanding of the quality of Oregon’s aquifers, and hopefully going forward get trending data to understand how those aquifers may change over time,” said Paige Haxton-Evans, DEQ statewide groundwater quality monitoring coordinator and report author.

Well users can find more information about groundwater contaminants and about maintaining healthy wells and drinking water by visiting the Oregon Health Authority’s Domestic Well Safety Program webpage.

This is the third geographic area DEQ has studied as part of its Statewide Groundwater Quality Monitoring Program, which evaluates the current condition of Oregon’s groundwater.

Read the full Walla Walla Basin 2020 Groundwater Quality report.

– Laura Gleim, public affairs specialist