America has built an average of two dams per day since the Revolutionary War—busier than beavers we have built more than 75,000 dams. Hoover Dam represents a major breakthrough (from an engineering point of view) and a major shift in emphasis from small dams (the vast majority) to huge dams which Hoover Dam’s engineers pioneered. Once the basics were down, more huge dams were built throughout the West. Perhaps every Western state has at least one. In the dam-building frenzy little attention was given to the unintended consequences. For example, the dams on the Klamath River in Oregon and Northern California reduced the salmon runs from more than 100 million tons harvested per season to being an endangered species. The hundreds of millions of dollars that have been subsequently spent to mitigate the damages were never factored into the calculus to build the dams. As an economist I can appreciate that, in fact, benefit-cost analysis was invented as a part of the major national policy questions at the time whether to build these things in the first place. As a rudimentary “science” however, almost all of the costs associated with building the dams were missed. For that matter, most of the costs are still missed by what is still a rudimentary science which makes it easier for decision makers to ignore those costs.