Rainbow Lake: The Anatomy of a Dam Failure

Abstract Only - Torrential rains produced up to 14 inches of precipitation across mid Michigan in September of 1986 and caused disastrous flooding which overwhelmed manmade structures throughout the region. The normally picturesque, privately-owned rainbow lake was stripped of its ability to hold water as the dam failed during the peak of the storm and was converted back to its natural riverine state. As is often times the case with privately-owned dams, maintenance responsibilities were shouldered by a group of citizens duly elected by their neighbors. Without the specialized knowledge which is necessary to adequately understand the complicated nuances of dam structures, those who were responsible for maintaining the structure were largely unaware of the risks and probability of major flood events. Post failure studies provide hindsight indicating that the dam failure could have been predicted with reasonable accuracy. Taking a hard look at the cause and effect of this dam failure provides insight to preventative measures which can be undertaken at other dam sites. This cam also illustrates the ability of a well-maintained vegetated earth embankment dam to withstand flood overtopping. Finally, the project highlights a unique means for financing a private facility through a municipal financing mechanism. Abstract Only.