View of a town by the Kennebec River. © NRCM   Have Dams Had Their Day? The early explorers of North America followed the waterways. Towns were built along riverbanks where water could be channeled into turning the grindstones and gears that produced flour, lumber, and textiles. The power produced by dams was first hydromechanical, then hydroelectric. As populations grew, dams provided reservoirs for drinking water, recreation, and crop irrigation. Bit by bit, America’s rivers were “tamed,” and by the 1940s dams were supplying as much as 40% of the nation’s electricity. Dam-building really took off after World War II, when dams were built across major rivers like the Missouri, the Colorado, and the Columbia. The official slogan of the Bureau of Land Reclamation was: “Our Rivers: Total Use for Greater Wealth.” The End of the Dam-Building Boom By the 1960s, however, the best hydroelectric sites were all dammed and the United States began relying more on fossil fuels. Hydropower now generates only about 10% of the nation’s electricity, and deregulation of the electric utility industry and technological innovation are unpleasant market forces confronting private dam owners.      1 of 9