but st like y other source velopmenin the u.,istory to look at dams the same damtwe took it t far.t. ago. - ere are ,000 dam at's thequivalen of blding on everay sincehomas jeerson (soft music continues) - [ben] dams have been a common part of the american landscape for centuries. most early communities were established on the banks of rivers, so dams could be built to divert river flows to water wheels to run machinery. arnd the te edisonad thlight bu dialed , e first droelectc pors was bng genered the u.sside niagaraalls. eawas being febyy phhyopower ane. power nedams wer beinbuilt soast that the engineering technology struggled to keep up. one of the worst disasters in u.s. history occurred in 1889, when pennsylvania south fork dam failed with no warning. the city of johnstown was leveled with 20 million tons of water, taking 2,200 lives. the flood is still referred to as a natural disaster, despite the fact that there's really nothing natural about impounding a river behind a poorly constructed wall. in the late 1800s, the government was faced with a tough choice, when they began