The purpose of the inspection was to assess the general condition of the dam with respect to safety and, based upon this inspection and available data, determine if the dam poses a hazard to human life or property. The following deficiencies were noticed during the visual inspection and are considered to have an adverse effect on the overall safety and future operation of the dam and spillway: A dense cover of small- to medium-size trees and brush that may conceal animal burrows exists on the upstream face of the dam. The upstream face of the dam is in an unkept state. The crest width of the dam is non-uniform and varies from approximately 60 feet to more than 100 feet. The course of the spillway outlet channel is not readily discernible due to the existence of dense brush and trees that begin at the end of the spillway control section. This dam, which is classified as intermediate in size and of high hazard potential, is specified to be the Probable Maximum Flood (PMF). Results of a hydrologic/hydraulic analysis indicated that the existing spillway is inadequate to pass the lake outflow resulting from a storm of PMF magnitude without overtopping the dam. The length of the downstream damage zone, should failure of the dam occur, is estimated to be six miles.

Hornsey Brothers Dam, Missouri Inventory Number 30101, was inspected. The dam is an earth dam constructed to impound a reservoir for recreational purposes. The dam is classified as having a high hazard potential by the St Louis District, Corps of Engineers (SLD). The SLD estimated damage zone length extends approximately 10 mi downstream of the dam. Within the first two miles there are at least eight occupied dwellings, several farm buildings, and two state highways. The findings of the visual inspection and review of available data indicate the dam and appurtenant structures are in generally good condition. Evidence of soil creep was identified near the downstream toe of the dam, but did not appear to pose a safety hazard to the dam at this time. Minor seepage was noted near the toe of the maximum section but water was not flowing at a measureable rate. Small trees and brush were noted on the crest and downstream face of the dam but did not obscure inspection. Seepage and stability analyses comparable to the requirements of the 'Recommended Guidelines for Safety Inspection of Dams' were not available.

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

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).

The Pierce Lake Dam, Missouri Inventory Number 30999, was inspected. This dam is classified as small due to its 37 ft height and storage capacity of 681 ac-ft. A small dam is one which is less than 40 ft in height and impounds less than 1000 ac-ft of storage. The St. Louis District, Corps of Engineers, has classified this dam high hazard; we concur with this classification. The estimated damage zone, as determined by the St. Louis District, Corps of Engineers, extends approximately five miles downstream. The community of Richwoods and several other occupied structures are located within the estimated damage zone. The inspection and evaluation indicate that the dam is in generally poor condition. Specific deficiencies that were noted are insufficient spillway capacity, very steep downstream slope, high erodibility of the embankment materials and lack of maintenance and periodic inspections. Also deemed as a deficiency is the lack of any stability or seepage analyses.