National Program for Inspection of Non-Federal Dams. Seymour Reservoir Number 4 Dam (CT 00325), Naugatuck River Basin, Oxford, Connecticut. Phase I Inspection Report.

Seymour Reservoir No. 4, a storage reservoir for public water supply is impounded by a main dam and two dikes. The main dam consists of an earth embankment approximately 425 feet long, with a top width of 20 feet, and a maximum height of 28 feet. The right dike begins approximately 100 feet to the right of the main dam, and consists of an earth embankment approximately 400 feet long, with a top width of 15 feet, and a maximum height of 22 feet. The left dike is located approximately 1,000 feet upstream of the main dam on the left bank of the reservoir, and consists of an earth embankment approximately 160 feet long, with a top width of 15 feet and a maximum height of 12 feet. The low level outlets or blowoffs consist of 10 and 8-inch cast iron pipes through the main dam embankment. The spillways consist of an 18-inch concrete overflow pipe through the right dike embankment, two 24-inch concrete overflow pipes through the main dam embankment, and an auxiliary earth spillway located at the left abutment of the left dike. Based on the visual inspection and a review of all available pertinent data, the dam is judged to be in poor condition. Some features that could affect the integrity of the dam and dikes include the seepage and possible internal erosion at the toe of the main embankment, possible internal leakage from the blowoff and spillway pipes, and the lack of filter layers between the riprap and embankment materials. The spillway is capable of passing 102 percent of the routed Test Flood outflow without overtopping the dam.