Results of a hydrologic/hydraulic analysis indicated that the spillway is adequate to pass lake outflow resulting from the 100-year frequency flood and the lake outflow corresponding to about 30 percent of the PMF lake inflow without overtopping the dam. According to the St. Louis District, Corps of Engineers, the length of the downstream flood damage zone, should failure of the dam occur, is estimated to be two miles. Accordingly, within the possible damage zone are four dwellings, Dam No. 30431, and two farm buildings. According to the Corps of Engineers, Dam No. 30431 has a significant hazard classification. A review of available data did not disclose that seepage or stability analysis of the dam were performed. This is considered a deficiency and should be rectified.

This dam has been classified as unsafe, non-emergency as a result of the application of the following criteria: spillway 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.

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. 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 15 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.

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.

Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.

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).