Salmon Creek Dam National Historic Civil Engineering Landmark

The Salmon Creek Dam—constructed from 1912 to 1914 near Juneau, Alaska, to support gold mining in the area—was the world’s first constant-angle (or variable radius) thin-arch dam constructed as a primary impoundment. This concept enabled an estimated reduction of 33% concrete over a conventional constant radius dam, proving its utility as a cost-effective approach for dam construction in V-shaped valleys; at the same time, this design was estimated to produce a factor of safety more than twice that of gravity dams. The concept of such a dam was first suggested in 1879, but was optimized by Lars Jorgensen, chief design engineer for the Salmon Creek project. After completion, this dam served as the prototype for many more constant-angle dams constructed throughout the world after 1914, and it remains in service today, still supplying water and power to Juneau. For the contributions of this project to the advancement of dam engineering, Salmon Creek Dam was designated a National Historic Civil Engineering Landmark by ASCE in 2020.