Colwash Fire Burns 8,000 Acres Near Prosser, Triggering Evacuations and Ash Fall on Tri-Cities

The Colwash Fire near Mabton, Washington burned about 8,000 acres by 7 p.m. on August 22, 2026, prompting evacuations, power outages and ash fall over the Tri-Cities.

Original report
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Industry impact

Regional wildfire activity near Prosser underscores wider western-airspace disruption risk that periodically affects general and business aviation routing and airport operations nearby.

A wildfire near Mabton, just west of Prosser, Washington, threatened homes, knocked out power, and sent ash falling on the Tri-Cities on Saturday evening, August 22, 2026. The fire, known as the Colwash Fire, had burned approximately 8,000 acres south of Interstate 82 by 7 p.m., and Washington state dispatched resources including five wildland strike teams ordered by mobilization specialists from the Fire Protection Bureau.

Evacuations were ordered for an area east of the Yakima-Benton County line, south of Highway 22, south and west of Highway 221, and north of Sellards Road, with warnings to be ready to evacuate issued for surrounding areas. The Red Cross opened an evacuation shelter at Prosser High School, located at 1500 Paterson Road.

The fire broke out at 7:40 a.m., and its cause remains under investigation, though thunderstorms had moved through the Yakima Valley and Tri-Cities area that morning. Officials with the State Fire Marshal's Office were en route and working remotely to coordinate resources.