The company exceeded restrictions on nitrogen-rich wastewater 90 times.

The Oregon Department of Environmental Quality fined the Lamb Weston potato processing facility in Hermiston $127,800 for overapplying wastewater containing nitrogen to farmland and causing nitrate groundwater contamination in the Lower Umatilla Basin, an area with longstanding groundwater contamination.

Lamb Weston has a DEQ water quality permit that allows it to use the nitrogen-rich wastewater from its potato processing plant and several other facilities to irrigate and fertilize nearby farms. The permit, however, includes limits on how much nitrogen can be applied to each crop. While nitrogen is a beneficial plant nutrient, applying too much to land can contribute to nitrate contamination in groundwater.

Lamb Weston exceeded these limits on 90 different occasions, resulting in approximately 446,990 pounds of excess nitrogen being applied onto the land application sites between 2015-2021. DEQ also cited Lamb Weston for failing to report non-compliance with the permit within five days of the violation, and for a separate spill of almost 25,000 gallons of industrial wastewater to soil.

There are many sources contributing to nitrate contamination in the area. The primary source of contamination in the area (about 70%) is from fertilizer use on irrigated farmland, according to the Lower Umatilla Basin Groundwater Management Area Action Plan. Additional contributors are dairy and cattle farms (about 20%), food processing facilities like the Lamb Weston that reuse wastewater to irrigate fields (about 5%), and residential septic systems and other sources (about 5%).

DEQ ordered Lamb Weston to develop and implement a plan to ensure compliance with the nitrogen limits in the permit and to conduct a remedial investigation of the aquifer under its land application sites.

DEQ discovered the violations while preparing a permit renewal for the facility. DEQ is also working with other industrial facilities in the area to ensure appropriate land application practices that protect the area’s groundwater.