Walla Walla means place of many waters. A fit name for the multiple streams that flow off the west side of the Blue Mountains into east end of the valley.
Walla Walla valley with the Blue Mountains to the east.
The City of Walla Walla is within the northeast of the valley
The many waters concept has been enhanced by irrigation diversions. Mill Creek flows through the City of Walla Walla. Upstream of the city are diversions which route water into other streams such that there are numerous year-round creeks flowing through city. In addition to the engineered diversion works upstream of the city, the stream route through the city is very engineered.
Mill Creek immediately east of downtown
Downstream of the above picture Mill Creek enters a tunnel and passed under portions of the downtown area. Down stream the creek remains heavily engineered and is contained with structures to reduce flooding and erosion. It may be the most engineered creek for its size of any stream in Washington State.
Early Walla Walla history made it clear that Mill Creek provided a huge benefit for the community, but the creek also periodically had very large floods that required significant flood control works.