Puyallup River - Natural History

Natural History

The Puyallup River and its main tributaries originate in the glaciers of Mount Rainier. These glaciers continually provide sediment such as silt and gravel to the rivers, creating sand and gravel bars. The thick sediment deposits in the stream beds lower water capacity, which causes the river to meander and flood during periods of high streamflow. It also causes the rivers to become braided and meandering. During the summer glacial meltwater dominates the streamflow, turning the Puyallup River turbid. In addition, the glaciers delay the onset of spring-summer runoff, compared to unglaciated river basins.

Historically, these factors resulted in frequent flooding and extensive floodplain wetlands, and provided a rich and complex habitat for fish and other animals. In addition, the river's mouth at Commencement Bay occupied an extensive tidal flat and wetland estuary delta. Urbanization and an extensive system of flood control structures such as dams, levees, and culverts, have radically altered much of the Puyallup River and its tributaries. The estuary delta at the mouth of the Puyallup River has been almost completely replaced with the facilities of the Port of Tacoma, with less than 5% of the original estuarine habitat remaining.

A fall run of Chinook salmon occurs on the river. Coho, Chum, and Pink salmon are also found in the river, along with Steelhead trout, sea-run Cutthroat trout, and a threatened species of Bull trout. Sockeye salmon are considered indigenous to the basin, but are rarely seen today.