The Von Der Ahe Dam is an earthfill structure approximately 37 ft. high and 660 ft. long at the crest. The appurtenant works consist of an 18-inch diameter concrete pipe at east abutment, a 24-inch diameter steel primary spillway pipe at Sta. 4 + 82 and a 9-inch diameter steel drawdown pipe at Sta. 4 + 95. Our inspection and evaluation indicates that the combined spillways do not meet the criteria set forth in the guidelines for a dam having the above size and hazard potential. The combined spillways will pass 33 percent of the Probable Maximum Flood without overtopping. The embankment appeared to be generally in good condition. Deficiencies visually observed by the inspection team were: (1) Erosion of downstream face at toe of embankment; (2) Erosion of upstream face of dam at elevation of primary spillway inlet; (3) Lack of trash rack on the primary spillway inlet; and (4) Apparent seepage through bedrock in the east abutment; and (5) Seepage through drain pipe valve.

This dam has been classified as unsafe, non-emergency by the St. Louis District as a result of the application of the following criteria: the combined capacity of the 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.

Lake Serene Dam is an earthfill structure approximately 37 ft high and 1200 ft long at the crest. The appurtenant works consist of a rock cut spillway with a concrete weir control structure located at the south abutment, and a 12-in. diameter siphon pipe located near the north end of the dam. Our inspection and evaluation indicates that 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 pass 27 percent of the Probable Maximum Flood without overtopping. Deficiencies visually observed by the inspection team were: (1) erosion at the contacts of the dam with the north and south abutments; (2) tree and brush growth on downstream face of dam; (3) animal burrows on face of dam; (4) concrete debris on dam face near spillway; and (5) debris in spillway outlet channel.

Lynch Lake Dam was inspected. Based on the criteria in the guidelines, the dam is in the high hazard potential classification, which means that loss of life and appreciable property loss could occur in the event of failure of the dam. The estimated damage zone extends approximately three miles downstream of the dam. Within the first two miles of the damage zone are nine dwellings, Highway NN and bridge which may be subjected to flooding, with possible damage and/or destruction, and possible loss of life. Lynch Lake Dam is in the small size classification since it is less than 40 feet high and impounds less than 1,000 acre-feet of water.

Gundaker Dam is an earth fill structure approximately 27.7 ft high and 970 ft long at the crest. The appurtenant works consist of rock cut primary spillway with concrete control section in the west abutment, an earth swale emergency spillway in the east abutment and a draindown pipe with valve at the downstream end. Our inspection and evaluation indicates that the combined spillways do not meet the criteria set forth in the guidelines for a dam having the above size and hazard potential. The combined spillways will pass 22 percent of the Probable Maximum Flood without overtopping. Deficiencies visually observed by the inspection team were: (1) wet areas (apparent seepage) at the west abutment-dam contact; (2) sloughing of the upstream face; (3) trees on the dam; (4) animal burrows; (5) clogged fish screen on the primary spillway weir; (6) and brush in the primary spillway downstream of the concrete control weir.

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.