One of the state’s largest milk producers has reached a settlement with an environmental group related to pollution from its processing facility in Sunnyside. 

Columbia Riverkeeper and Darigold recently agreed to a consent decree resolving a 2025 lawsuit that alleged the dairy cooperative violated the federal Clean Water Act for more than four years, according to a release. 

The agreement requires Darigold to pay $2 million to the Yakama Nation. It also must submit an engineering report – subject to approval by the state Department of Ecology – outlining how it will meet clean water standards.  

The company could face additional penalties paid to the tribe for any future pollution exceedances over the next 18 months. 

“This is an incredible victory for clean water and should lead to lasting improvements to the Yakima River Basin,” said Teryn Yazdani, staff attorney for Columbia Riverkeeper, in a statement. “Clean water is a basic human right, and every corporation must do its part to protect local rivers and comply with laws that protect public health and the environment.” 

Darigold said in a statement to the Tri-Cities Area Journal of Business that it has worked with the Department of Ecology and the Port of Sunnyside to manage wastewater and disputes that its operations caused harm. 

“In the interest of maintaining strong relationships with our many partners and stakeholders in Sunnyside and surrounding areas, we are pleased to have reached a resolution to this matter and put it behind us,” Darigold said in its statement. 

Columbia Riverkeeper’s original lawsuit said that two of the Sunnyside facility’s discharge points, which are supported by the port’s Industrial Wastewater Treatment Facility, send its wastewater onto agricultural land, which then finds its way into nearby Sulphur Creek, a tributary of the Yakima River. Those pollutants contribute to low dissolved oxygen in water, harming fish and other aquatic life. 

While the facility has a permit to release treated wastewater, Columbia Riverkeeper claimed it violated that permit by exceeding effluent limitations, failing to properly monitor and report discharges, and failing to properly operate and maintain all facilities or systems of treatment control to achieve compliance. 

Neither a court nor state ecology officials have found Darigold at fault, the cooperative said in its statement. The company also continually evaluates and upgrades its wastewater treatment facilities and has made improvements over the last year, with additional improvements planned. 

The Yakama Nation intends to use money from the settlement to battle infestations of water stargrass, a native plant that can contribute to higher water temperatures during hot periods by slowing water flow and trapping heat. The plant has overtaken stretches of the lower Yakima River due to low flows and agricultural nutrients in the water.