- Mill Creek (Walla Walla River tributary) (Wikipedia)
Mill Creek is a 36.5-mile-long (58.7 km) tributary of the Walla Walla River, flowing through southeast Washington and northeast Oregon in the United States. It drains from the western side of the Blue Mountains into the Walla Walla Valley and flows through the city of Walla Walla, which draws most of its water supply from the creek. The creek is named for the sawmill built in 1845 by Marcus Whitman, one of the first European settlers in the valley.