Ithamar A. Beard, an engineer of some prominence in New England, surveyed the mill brook and selected the best site for a storage dam. Contractor Simeon Cobb, knowledgeable of contemporary civil engineering practices, made major changes to the dam's original design, converting the linear dam into a gentle arch.
Gravity

YearAdded:
Image Credit: Courtesy Wikipedia/Ymblanter (CC BY-SA 3.0)Image Caption: The Ascutney Mill Arch-Gravity DamEra_date_from: 1834
1970

The Bonneville Dam, Columbia River Power and Navigation System consists of 55 major projects on Oregon's Columbia River and is said to be the largest hydroelectric system in the world.
The Columbia River forms part of the border between Washington and Oregon and flows inland through the only waterway that crosses the Cascade Mountains. To harness the energy of the ninth longest river in North America, engineers developed unique design and construction approaches to overcome problems caused by depth of water, current velocity, and an irregularly-shaped river bottom.
YearAdded:
Image Credit: Courtesy Flickr/Ann Larie Valentine (CC BY-SA 2.0)Image Caption: The impressive power of the Bonneville DamEra_date_from: 1938
1987