National Dam Safety Program. Macon Lake Dam (MO 10153), Grand - Chariton Basin, Macon County, Missouri. Phase I Inspection Report.

The purpose of the inspection was to make an assessment of the general conditions of the dam with respect to safety, based upon available data and visual inspection, in order to determine if the dam poses hazards to human life or property. The inspection and evaluation indicate that the spillway does not meet the minimum criteria set forth in the recommended guidelines for an intermediate dam having a high hazard potential. The Probable Maximum Flood is the appropriate spillway design flood. The spillway will pass the 100-year flood (a flood having a 1 percent probability of being exceeded in any year) without overtopping the dam. The spillway will pass 55 percent of the Probable Maximum Flood without overtopping the dam. The Probable Maximum Flood (PMF) is defined as the flood that may be expected from the most severe combination of critical meteorologic and hydrologic conditions that are reasonably possible in the region. The height of the dam should be increased and/or the spillway size or shape should be changed to pass the Probable Maximum Flood without overtopping the dam.