This report was prepared under the National Program of Inspection of Non-Federal Dams. This report assesses the general condition of the dam with respect to safety, based on available data and on visual inspection, to determine if the dam poses hazards to human life or property. (Author).

Fon-du-lac Subdivision Dam was inspected by an interdisciplinary team of engineers. The purpose of the inspection was to make an assessment of the general condition 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. Failure would threaten the life and property of ten families and cause appreciable damage to two county roads. Our inspection and evaluation indicates the dam is deficient in that the spillway is inadequate. The guidelines for a dam having the above size and hazard potential require that the spillway be capable of passing a one-half PMF (Probable Maximum Flood). The Probable Maximum Flood is defined as the flood discharge that may be expected from the most severe combination of critical meteorologic and hydrologic conditions reasonably possible in the region. Considering the small volume of water impounded, the large floodplain downstream and the three groups of farm buildings downstream, one-half PMF is the appropriate spillway design flood. A 20% PMF will begin to overtop the dam. The lake and spillway are adequate to contain a 1% annual probability flood (100-year flood) without overtopping the dam.

This report was prepared under the National Program of Inspection of Non-Federal Dams. This report assesses the general condition of the dam with respect to safety, based on available data and on visual inspection, to determine if the dam poses hazards to human life or property. (Author).

This report was prepared under the National Program of Inspection of Non-Federal Dams. This report assessess the general condition of the dam with respect to safety, based on available data and on visual inspection, to determine if the dam poses hazards to human life or property. (Author).

This report was prepared under the National Program of Inspection of Non-Federal Dams. This report assesses the general condition of the dam with respect to safety, based on available data and on visual inspection, to determine if the dam poses hazards to human life or property. (Author).

This report assesses the general condition of the dam with respect to safety, based on available data and on visual inspection, to determine if the dam poses hazards to human life or property. The St. Louis District has classified this dam as unsafe because of a large seep on the downstream embankment slope near the left abutment contact, and a seriously inadequate spillway that will pass only 32 percent of the Probable Maximum Flood.

This report was prepared under the National Program of Inspection of Non-Federal Dams. This report assesses the general condition of the dam with respect to safety, based on available data and on visual inspection, to determine if the dam poses hazards to human life or property. (Author).

This dam has been classified as unsafe, non-emergency by the St. Louis District as a result of the application of the following criteria: Spillways will not pass 50 percent of the Probable Maximum Flood without overtopping the dam; Overtopping of the dam could result in failure of the dam; and Dam failure significantly increases the hazard to loss of life downstream.

The purpose of Dresser No. 4 Dam is to impound tailings from a barite separation and beneficiation operation. The dam completely encircles the impoundment except for a 300-foot wide breach at the north (up-stream) end where the structure failed in 1975. The dam cannot retain water in its present state because of this breach in the dam. This dam is classified as large. The U.S. Corps of Engineers has classified it as having a high downstream hazard potential to indicate that failure of this dam could threaten life and property. The damage zone, estimated by the U.S. Corps of Engineers, extends about 6 miles downstream of the dam. Since the embankment cannot retain water, the overtopping potential of the embankment was not analyzed. Instead, studies were made to estimate the amount of flow that could occur in the diversion ditch (located to the west and south of the impoundment) under different flood conditions. It was calculated that the diversion ditch could pass a 100-year flood probably without significant erosion of the ditch or adjacent embankment toe. However, it was estimated that the ditch cannot pass 50 percent of the Probable Maximum Flood without significant erosion of the ditch and adjacent embankment materials.