Puyallup River
| Puyallup River | |
|---|---|
Map of the Puyallup River watershed | |
| Location | |
| Country | United States |
| State | Washington |
| Counties | Pierce |
| Cities | Orting, Puyallup, Tacoma |
| Physical characteristics | |
| Source | Mount Rainier |
| • coordinates | 46°51′50″N 121°57′4″W / 46.86389°N 121.95111°W |
| • elevation | 2,280 ft (690 m) |
| Mouth | Puget Sound |
• location | Commencement Bay |
• coordinates | 47°16′10″N 122°25′42″W / 47.26944°N 122.42833°W |
• elevation | 0 ft (0 m) |
| Length | 45 mi (72 km) |
| Basin size | 948 sq mi (2,460 km2) |
| Discharge | |
| • location | Puyallup |
| • average | 3,313 cu ft/s (93.8 m3/s) |
| • minimum | 400 cu ft/s (11 m3/s) |
| • maximum | 57,000 cu ft/s (1,600 m3/s) |
| Basin features | |
| Tributaries | |
| • right | Mowich River, Carbon River, White River |
The Puyallup River (/pjuːˈæləp/ pyew-AL-əp) is a river in the U.S. state of Washington. About 45 miles (72 km) long, it is formed by glaciers on the west side of Mount Rainier. It flows generally northwest, emptying into Commencement Bay, part of Puget Sound. The river and its tributaries drain an area of about 948 square miles (2,460 km2) in Pierce County and southern King County.
The lower, northwestern half of the river's watershed is a complex amalgam of glacial and tectonic features dating back to the Pleistocene, as well as more recent (Holocene) changes caused by a series of lahars which flowed down from Mount Rainier between 5,600 and 800 years Before Present. The valley's 150,000 residents are at risk from future lahars. For this reason, the United States Geological Survey has installed a lahar warning system.