THE first steps toward formation of the Miami Conservancy Dist. were taken out of the wreckage of the city of Dayton, Ohio, immediately after the disastrous flood of 1913 a flood which did more than $100,000,000 worth of direct property damage in the valley of the Miami River. Ten years later, following pioneering jobs in legislation, engineering, financing, and many fields of human relations, the district had provided the Miami valley with flood protection works that included river improvements at nine cities and dams on the Miami River and four of its tributaries. The story of that ten years of unremitting struggle against obstacles raised not only by the nature of the problem itself, but by other interests in the area and by the economic dislocations of World War I, has been told in detail elsewhere (1). Of particular interest to the water works profession is the type of dam used on the project. The dams of the Miami Conservancy Dist. were almost without precedent in that they have no gates, but, instead, permanent openings through which water can flow at all times. Figure 1 shows the outlet conduits of the Germantown Dam, one of the Miami Conservancy dams, during ordinary stage, and Fig. 2 shows the same dam during flood. When these dams were built there were two or three very small structures in the United States operating on somewhat the same principle, and in France, two man-made narrowings of the Loire River channel, dating back some centuries, provided similar action although they were intended for entirely different purposes. In the more than thirty years since the construction of the Miami Con-