The Delta River is a river in eastern Alaska, United States. It is a tributary of the Tanana River, and by extension the Yukon. Originating from the Tangle Lakes, the river flows north through the Alaska Range, carving a valley perpendicular to the east-west mountain range. Initially clear and slow-moving, it becomes faster and silty after taking in Eureka Creek, its first major tributary. As it flows through the Alaska Range, it takes in meltwater from various glaciers and glacier-fed streams. At the end of its roughly 80-mile (130 km) course, the river meets the Tanana near the settlements of Big Delta and Delta Junction. The geology of the basin is highly complex, with various glacier-shaped landforms and alluvial deposits from the river. Dust from the river valley is spread by the wind and forms a layer of loess to the west of the river. The river basin is home to various birds, mammals, and plants, while the water hosts fish such as northern pike and arctic grayling.