 The Portland Metro Urban Growth Boundary (UGB) bisects the county.The county's highest point is South Saddle Mountain at 3,464 feet (1,056 m) above sea level in the Northern Oregon Coast Range.Most of the county is in the Tualatin Valley, formed by the Tualatin Mountains to the east and north, the Chehalem Mountains to the south, and the Northern Oregon Coast Range to the west and north.