at Hungry Horse Dam in Montana - September 1, 2009
Hungry Horse Dam is an arch dam in the Western United States, on the South Fork Flathead River in the Rocky Mountains of northwest Montana. It is located in Flathead National Forest in Flathead County, about fifteen miles south of the west entrance to Glacier National Park, nine miles southeast of Columbia Falls, and twenty miles northeast of Kalispell. The Hungry Horse project, dam, and powerplant are operated by the U.S. Bureau of Reclamation. The entrance road leading to the dam is located in Hungry Horse.
The purposes of the Hungry Horse Project authorized by law are irrigation, flood control, navigation, streamflow regulation, hydroelectric generation, and other beneficial uses such as recreation. However, no irrigation facilities were built and the project has no irrigation obligations. Hydroelectric power generation and flood control are the primary purposes of the dam. The dam, reservoir, and surrounding area are used for recreation.
(above and below quotes are from https://en.wikipedia.org/wiki/Hungry_Horse_Dam)
At 564 feet in height, the dam was the third largest and second highest concrete dam in the world at the time of its completion in 1953, with a volume of 3,100,000 cubic yards. The dam's spillway is the highest morning glory structure in the world. The spillway is controlled by a 64-by-12-foot ring gate. The surface elevation of the reservoir is 3,560 feet above sea level.
The dam is managed to provide beneficial flow conditions and to provide safe passage for migrating juvenile fish to reach the Columbia River Estuary and the Pacific Ocean.