The Eklutna River is a 22 mile (35 km) long river located in the Southcentral region of the U.S. state of Alaska. A degraded anadromous stream of glacial origin, it originates at Eklutna Glacier and flows through Eklutna Lake and a canyon up to 350 feet (107 m) deep, emptying into the Knik Arm of Cook Inlet approximately 17 miles (27 km) northeast of Anchorage. It has one significant tributary, Thunderbird Creek, which enters the south bank about 1 km (0.6 mi) upstream from where the river exits the canyon and forms an alluvial fan. Due to water impoundments on the Eklutna River for power generation, Thunderbird Creek is currently the main source of water in the river.