The flooding in the lower basin of the Colorado River during the spring and summer of 1983 led to discussion of the management of the heavy spring runoff from the upper basin. This analysis stresses that the reasons for the flooding go beyond the climatic events of the year and the U.S. Bureau of Reclamation's response to them. It is argued that the flooding is the result of the convergence of three factors: 1) the 17-year period of filling Lake Powell (Glen Canyon Dam) has ended and the system of water storage reservoirs on the river now considered full; 2) during the filling period, physical encroachment into the lower basin flood plain accelerated; and 3) the climatic variability experienced in the Colorado River Basin. The flooding in the lower basin of the Colorado River during the spring and summer of 1983 led to discussion of the management of the heavy spring runoff from the upper basin. This analysis stresses that the reasons for the flooding go beyond the climatic events of the year and the U.S. Bureau of Reclamation's response to them. It is argued that the flooding is the result of the convergence of three factors: 1) the 17-year period of filling Lake Powell (Glen Canyon Dam) has ended and the system of water storage reservoirs on the river now considered full; 2) during the filling period, physical encroachment into the lower basin flood plain accelerated; and 3) the climatic variability experienced in the Colorado River Basin.