The main Puyallup River flows north and northwest from Mount Rainier. The tributary Mowich River, which also flows from glaciers on Mount Rainier, joins the Puyallup from the east. Below the Mowich confluence, the Puyallup River flows through a rugged region of mountains and foothills. The river is dammed at Electron Diversion Dam shortly below the Mowich confluence. The dam diverts a portion of the Puyallup River into a long flume, which runs for several miles to Electron, where the water is passed through turbines in a hydroelectric powerhouse before being returned to the river. The Puyallup River passes through a steep and narrow gorge between Electron Dam and the powerhouse.