Malheur County /mælˈhɪər/ is a county located in the southeast corner of the U.S. state of Oregon. As of the 2010 census, the population was 31,313. Its county seat is Vale, and its largest city is Ontario. The county was named after the Malheur River, which runs through the county. "Malheur" is French for misfortune.Malheur County is included in the Ontario, OR-ID Micropolitan Statistical Area, which is also included in the Boise City-Mountain Home-Ontario, ID-OR Combined Statistical Area.