The Internet Archive has some excellent history resources, especially in the way of film. A search for Grand Coulee reveals this newsreel report about the opening of the dam. Notice they were still pitching the dam as a benefit for small farmers, which is not at all how it worked out. Also of interest is a 1947 Coronet Instructional Film The Mighty Columbia River. (I attempted to embed these videos as with YouTube but it did not work for some reason.) And check out the wonderfully cheesy Hanford Science Forum described as a "television program sponsored by General Electric Company for telecasting to residents of the Richland, Washington area." In this episode a Hanford biologists assures us that the "mildly radioactive" discharges from Hanford are perfectly harmless.