The dam is located across Mill Creek, approximately three miles upstream from its confluence with the Tuscarora Creek in Tuscarora Township, Bradford County, Pennsylvania. The dam is classified to be in the significant hazard category. It is estimated that failure of the dam may cause loss of a few lives and some property damage in these areas. The onsite inspection of Mill Creek Dam consisted of: Visual inspection of the embankment, abutments, and embankment toe, Visual examination of the spillway and the visible portions of the outlet works, and Evaluation of downstream area hazard potential.

Based on the evaluation of the existing conditions, the condition of Cooks Pond Dam is considered to be unsafe/nonemergency due to the seriously inadequate spillway capacity and structural deficiencies. The condition of the embankment is considered to be poor. The dam is old and in a general state of disrepair. The crest of the dam is irregular and the center of the dam appears to have settled. The stone wall along the downstream toe is irregular and bulging. The toe of the wall is swampy, caused by a general underseepage. In view of these observations, the overall stability of the dam is considered to be questionable, requiring further investigation and implementation of measures to improve the stability of the dam. The spillway capacity was evaluated according to the recommended procedure and was found to pass less than 10 percent of the Probable Maximum Flood (PMF) without overtopping the embankment. This capacity is less than the required spillway capacity of one-half PMF relative to the size and hazard classification of the dam. Because the spillway capacity is less than 50 percent of the PMF and it is estimated that failure of the dam due to overtopping would significantly increase the downstream hazard of loss of life compared to that which would exist just before failure, the spillway is considered to be seriously inadequate, and consequently the condition of the dam is considered to be unsafe/nonemergency.

The dam is located approximately 2 miles northwest of the Village of Colley, Wilmot Township, Bradford County, Pennsylvania. The inspection consisted of: Visual inspection of the retaining structure, abutments and toe; Examination of the spillway facilities, exposed portion of any outlet works and other appurtenant works; Observations affecting the runoff potential of the drainage basin; and Evaluation of the downstream area hazard potential. The dam appears to be in good condition and adequately maintained. From a brief survey conducted during the inspection, it was noted that the low spot on the crest of the dam exits at the top left edge of the spillway crest. It was observed during the inspection that a new concrete cap had been placed on the structure. The concrete appeared to be in good condition. The dam was constructed with dry rubble masonry with an upstream earthfill. No concrete exists on the downstream face of the structure or on the bench located along the downstream face of the structure. The rubble masonry appeared to be in good condition and well maintained.

Based on a visual inspection, operational history, and available engineering data, the facility is considered to be in good condition. The size classification of the facility is intermediate and its hazard classification is considered to be high. In accordance with the recommended guidelines, the Spillway Design Flood (SDF) for the facility is the PMF (Probable Maximum Flood). Results of the hydrologic and hydraulic analysis indicate the facility will pass and/or store only about 45 percent of the PMF prior to embankment overtopping. A breach analysis indicates that failure under less than 1/2 PMF conditions could lead to increased downstream damage and potential for loss of life. Thus, based on screening criteria provided in the recommended guidelines, the spillway is considered to be seriously inadequate and the facility unsafe, non-emergency. Calculations also indicate that if the spillway were constructed in accordance with available desing drawings, the facility could pass and/or store approximately 63 percent of the PMF.

The visual inspection, operational history, and hydrologic/hydraulic analysis indicate that the facility is in excellent condition. The size classification of the facility is intermediate and its hazard classification is considered to be high. In accordance with the recommended guidelines, the Spillway Design Flood (SDF) for the facility is the PMF (Probable Maximum Flood). Results of the hydrologic and hydraulic analysis indicate the facility is capable of passing and/or storing the PMF. Consequently, its spillway is considered adequate. It is recommended that the owner immediately (a) provide positive drainage for the area between the left spillway wingwall and left abutment hillside and (b) repair and seal all concrete cracks observed along the left spillway wingwall. (Author).