Zander Lake Dam is located in Montgomery County of the State of Missouri on an unnamed tributary of the Scratchers Branch of the Little Loutre Creek. The purpose of the dam is to impound water for recreational use as a private lake. The visual inspection uncovered nothing of a consequential nature which would require immediate remedial action. However, some conditions were observed which could adversely affect the dam and the spillway in the near future.

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 appears to be in satisfactory condition. However, the dam does not have adequate spillway capacity. Considering the number of inhabited dwellings, a state highway and an oil depot being located downstream of the dam, the PMF is considered the appropriate spillway design flow for A.C. Schneider Lake Dam. The inspection and evaluation indicates that the reservoir/spillway system can accommodate approximately 5 percent of the Probable Maximum Flood without overtopping the dam. It also indicates that the reservoir/spillway system can not accommodate the one-percent chance flood without overtopping, however, the reservoir/spillway system of A.C. Schneider Lake Dam can accommodate the ten-percent chance flood without overtopping. Other deficiencies noted by the inspection team were: the erosion gully along the downstream left abutment/embankment contact, the trees on the downstream and upstream slope of the dam, wave erosion on the upstream slope, the unsupported length of the principal spillway pipe at the outlet, the eroded gulley in the emergency spillway channel, some vegetative growth around the principal spillway inlet, a need for periodic inspection by a qualified engineer and a lack of maintenance schedule. The lack of seepage and stability analyses on record is also a deficiency that should be corrected.

Riss Lake Dam was inspected 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. Our inspection and evaluation indicates the spillway does not meet the criteria set forth in the guidelines for a dam having the above size and hazard potential. The spillway will not pass the probable maximum flood without overtopping but will pass 90 percent of the probable maximum flood, which is greater than the estimated 100-year flood. The spillway design flood recommended by the guidelines is 100 percent of the probable maximum flood. The probable maximum flood is defined as the flood discharge which may be expected from the most severe combination of critical meteorologic and hydrologic conditions which are reasonably possible in the region. Deficiencies visually observed by the inspection team were erosion of the upstream face due to wave action, ponded water on the dam crest due to poor drainage of rainwater, trees and brush growing on the embankment, animal burrows, and seepage at several locations below the dam.

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 visual inspection, in order to determine if the dam poses hazards to human life or property. The inspection and evaluation indicate that the spillways do 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 spillways will pass 22 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.

This dam has been classified as unsafe, non-emergency by the St. Louis District as a result of the application of the following criteria: (1) Spillway will not pass 50 percent of the Probable Maximum Flood; (2) Overtopping could result in dam failure; and (3) Dam failure significantly increases the hazard to loss of life downstream.