Dworshak Dam is a concrete gravity dam in the western United States, on the North Fork of the Clearwater River in north central Idaho. In Clearwater County, the dam is located approximately northwest of Orofino and impounds the Dworshak Reservoir for flood control and hydroelectricity generation. With a height of , Dworshak is the third tallest dam in the U.S. and the tallest straight-axis concrete dam in the Western Hemisphere. Construction of the dam by the U.S. Army Corps of Engineers (USACE) began in 1966 and was completed in 1973. Lacking fish ladders, the dam blocks fish passage and completely extirpated anadromous fish migration into the upper reaches of the North Fork and its tributaries in Idaho. History The proposal for Dworshak Dam originated in a 1953 USACE survey of the lower Snake River drainage basin for suitable sites to develop reservoir storage and hydroelectric power generation. Dworshak was one of seven dam sites considered on the Snake, Salmon and Clearwater River systems. The final site for Dworshak Dam was chosen at a point on the North Fork of the Clearwater above its confluence with the larger Clearwater River. The project was authorized on October 23, 1962, as Bruces Eddy the name was later changed to honor Senator Henry Dworshak (1894–1962), who was instrumental in gaining congressional approval for the The dam was controversial from the start, because it would block fish migration and its reservoir would flood a large portion of the winter range of elk in the Clearwater River basin. The North Fork of the Clearwater River had an excellent run of steelhead trout and "may have been the finest population of large-size steelhead in the world". However, proponents of the project held that the construction of a fish hatchery would maintain the river's steelhead runs, and that the construction of the dam would render other dam projects in the Clearwater River basin unnecessary. Another big incentive for the project was flood control; supporters of Dworshak cited a devastating flood in 1948, when the Clearwater River reached a peak of —eleven times its normal flow—as further reason for the construction of a large storage dam. While clearing and preparations at the dam site were underway as early as June 1965, actual construction did not begin until early 1966 with the excavation of a diameter diversion tunnel and the creation of a high cofferdam to divert the river around