The Powder River is a significant tributary of the Yellowstone River, flowing approximately 375 miles through northeastern Wyoming and southeastern Montana. The river and its drainage system include the mainstem Powder River, the Little Powder River, and intermittent tributaries like Mizpah Creek and Locate Creek. Originating in the Bighorn Mountains in Wyoming, the Powder River flows northward through a rugged landscape dominated by plains grassland and shrub grassland complexes. The river is named for the sand along portions of its banks that resembles powder or dust. As an undammed river, the Powder exhibits a relatively natural hydrograph with fluctuations typically consisting of rapid but short-duration elevated flows resulting from Wyoming mountain snowpack melt or local rain events. The watershed is characterized by highly erodible soils with gumbo, clay, and silt, which contributes to its high sediment load and turbidity - features that play crucial ecological roles for native fish species.