There is a Navy "bombing range" out in the God-forsaken scrub desert west of Boardman, and southeast of Arlington. In the early '70s, we would regularly hear sonic booms in Stanfield, which is about 20 miles east of Boardman, and 15 miles east (downwind) of the Umatilla Army Depot, one of the homes of the Army's chemical weapons stockpile.
I know it's fairly common knowledge, but I sure wish people would quit pointing out Umatilla on public forums like this.