The Puyallup watershed was divided into two parts in 1988 to make management easier. The Upper Puyallup covers approximately 75 percent of the entire Puyallup river basin, draining 766 square miles between Orting, the crest of the Cascades, and the peak of Mount Rainier. Approximately 96 percent of the upper watershed is forested. Steep hillsides and glacial streams are a primary feature of the watershed, but dams and man-made diversions on the Puyallup and White rivers interrupt the water’s natural flow. The diversions significantly reduce the flow of water in the bypassed segments of the two rivers.
The Lower Puyallup is 117,000 acres, reaching from Buckley to Commencement Bay and then south to Orting. There are a number of wetlands in the lower watershed, and dense, poorly drained soils left over from the Osceola and Electron mudflows. Average precipitation in the lower watershed is 40 to 49 inches annually.
- Counties: King, Kittitas, Pierce, Yakima
- National Estuary Programs: Puget Sound
- Other Watersheds Upstream: None
- Other Watersheds Downstream: Puget Sound