National Program for Inspection of Non-Federal Dams. Amston Lake Dam (CT 00544), Connecticut River Basin, Hebron, Connecticut. Phase I Inspection Program.

The dam is an earth embankment approximately 10 feet wide at the top and 400 feet long with the top approximately 10 feet above the streambed of an unnamed tributary to Raymond Brook. A central portion of the earth dam is comprised of a high area of natural ground to within a horizontal distance of 20 feet from the left spillway abutment. The spillway is a 15 foot long broad crested concrete weir of trapezoidal cross-section with vertical concrete training walls. The low level outlet is an approximately 1 foot square conduit through the spillway section. The flow through the conduit is regulated by a hand operated submerged gate mechanism adjacent to the upstream face of the spillway section. Based upon the visual inspection at the site and past performance, the dam is judged to be in poor condition. There was erosion evident on the upstream slope and crest of the dam, as well as numerous footpaths on the downstream slope. There were also significant amounts of seepage observed on the downstream slope and along the downstream toe of the dam. Other deficiencies include trees and brush on the dam embankment and a low beach area adjacent to the left end of the dam. Based upon hydraulics computations, the spillway capacity is 180 cfs which is equivalent to 113 percent of the routed Test Flood outflow. It should be noted that the above figures assume the low area at the left end of the dam to be raised to the top of the dam.