The [Mill Creek] Watershed area is protected. It is closed to the public allowing only limited access in coordination with the U.S. Forest Service. It is patrolled by a City Watershed Attendant and United States Forest Service personnel.
Youngs Bay (Wikipedia) Youngs Bay, or Youngs River Bay, is located in the northwestern corner of the U.S. state of Oregon. The Youngs River meets the Columbia River at this point, which is situated between Astoria and Warrenton.
In addition to this primary source [Mill Creek Watershed], the City [of Walla Walla] also has seven deep (800-1400’) basalt wells used to supplement supply when stream levels decline in summer months.