The project, built about 1891 has a total length of 545 feet consisting of a 340-foot masonry core with earth fill on the upstream and downstream sides, a 115 foot long earth embankment at the right end of the dam, and sections of concrete corewall at each end. A 71-foot broad-crested masonry spillway is located at the central portion of the dam. The top of the dam (elevation 312.0) is 7 feet wide and 16.5 feet above the Harbor Brook streambed. The maximum storage capacity with the pond level to the top of the dam is approximately 216 acre-feet of water. A gatehouse, located upstream and adjacent to the right end of the spillway, contains two valves which regulate a 20-inch blowoff and a 12-inch supply main which once led to the Bradley and Hubbard Corp. In accordance with the Army Corps of Engineers's Guidelines, Bradley Hubbard Reservoir Dam is classified as a high hazard, small size dam. The test flood range is from one-half to full Probable Maximum Flood (PMF). The selected test flood for Bradley Hubbard Reservoir Dam is equivalent to the PMF. Peak inflow to the reservoir at the test flood is 1500 cubic feet per second (cfs); peak outflow is 1325 cfs with the dam overtopped by 0.9 feet. The spillway capacity with the reservoir level to the top of the dam is 223 cfs, which is equivalent to 17% of the routed test flood outflow.

Black Pond Dam is a stone masonry and earth embankment structure approximately 100 feet long and 26 feet high with a 25-foot wide paved road (Birdsey Avenue) on the crest. A majority of the downstream embankment consists of a vertical stone masonry face. The 14-foot wide spillway is a 14-foot by 3-foot concrete culvert under the road at approximately the center of the dam. There is a mortared stone gate inlet structure that controls a 20-inch cast iron water main that passes through the base of the dam. The water main connects into the City's distribution network, and is used only for emergencies. There is no low-level discharge. The pond is presently used for recreation. The drainage area is 1.2 square miles and the reservoir has approximately 353 acre-feet of storage capacity. The assessment of the dam is based on the visual inspection, past operational performance and hydraulic/hydrologic computations. The dam is judged to be in fair condition with several areas that require attention. These areas include seepage through the dam, missing mortar in the downstream face, trees on the embankments as well as along the toe of the dam and the lack of a low-level discharge pipe. The test flood for this dam is 1/2 the PMF and is calculated to be 560 cfs. The spillway capacity at the top of the dam is 250 or 45 percent of the test flood outflow. The test flood outflow will overtop the dam by 1.1 feet.

The dam consists of two sections. The portion of the dam from the spillway 185 feet to the left is an earthen embankment on the upstream side of a rubble masonry retaining wall. The remaining portion of the dam to the left of the retaining wall is an earthen embankment. According to the existing information, a rubble masonry corewall exists from the spillway 260 feet to the left. The spillway is reported as a 50-foot-wide concrete weir flowing to a steep channel cut into natural rock formations. A 16 inch diameter high level intake approximately 900 + or - feet to the right of the dam was used as a supply main. The supply main is operable, however the reservoir is not used as a water supply due to the turbidity and poor color quality of the water. A 12 inch, low level inlet passes through the dam, but is presently inoperable. Based upon visual inspections at the site and past performance history, the dam is judged to be inf air condition. No evidence of structural instability in the retaining wall or the embankment portions of the dam was observed. However, the masonry retaining wall is very irregular making it impossible to detect any misalignment or movement of the wall. There are areas requiring attention. Based upon our hydraulic computations, the spillway capacity is 850 cubic feet per second, which is equivalent to approximately 28 percent of the Test Flood. Peak inflow to the reservoir is 3,500 cubic feet per second; peak outflow (Test Flood) is 3,000 cubic feet per second with the dam overtopped 0.8 feet.

The Broad Brook Dam is a concrete dam that is 210 feet long with a 70 foot spillway. It has a gate house with a 30 inch diameter blowoff and a 30 inch diameter water main. Based on the visual inspection, records available at the site and past operational performance, the dam is judged to be in poor condition. A review of the limited engineering data available reveals that there are areas of concern that should be corrected or investigated further as to their effect on the integrity of the dam. The east bank on the downstream side of the dam shows signs of fairly heavy seepage. This condition should be investigated further. The project spillway will pass only 26 percent of the estimated Probable Maximum Flood (PMF), the recommended spillway test flood. Therefore, further hydrologic and hydraulic studies are recommended to refine the spillway test flood, determine the ability of the dam to withstand overtopping, and if appropriate, measures for increasing spillway capacity.

The dam is comprised of an earthen embankment on the upstream side of a near-vertical rubble stone masonry wall, which is approximately 340 feet in length and rises approximately 37 feet above the original streambed elevation of the Mill River. The upstream earthen embankment is approximately 20 feet wide at the dam crest and has an upstream slope with a maximum inclination of 3 horizontal to 1 vertical. The right portion of the spillway is a concrete compounded circular crest with a sloped downstream face. The left portion of the spillway is a side channel concrete ogee section. The area below the dam is developed with industrial buildings, a high school, and residential structures. Based upon the visual inspection at the site and past performance of the dam, the dam is judged to be in good condition. No evidence was observed of structural instability in the earthen embankment or the masonry wall. The condition of both the embankment and wall appears to be good. There are some areas requiring attention. Based upon our hydraulics computations, the spillway capacity is 9700 cubic feet per second, which is equivalent to approximately 21 percent of the Test Flood. Peak inflow to the reservoir is 48,600 cubic feet per second; peak outflow (Test Flood) is 46,500 cubic feet per second with the dam overtopped 4.4 feet.

Plainville Reservoir Dam is an earthen embankment dam with a maximum height o 17 feet and a length of 688 feet. A concrete spillway section, 15 feet wide, is located near the left abutment. The upstream face has a slope of 1.5:1, and is protected by riprap. The downstream face has a slope of 1.5:1. There are two 6-inch diameter blowoffs located adjacent to the two gatehouse structures located downstream of the dam. Plainville Reservoir has a storage volume of 528 acre-feet; the size classification is thus small. In general, the dam was judged to be in fair condition. The vertical and horizontal alignment is good; however, a slight dip in the crest was noted in the vicinity of the downstream gatehouse. Several windows were observed in the upstream riprap, which ends about 2 feet below the crest of the dam. Some small seeps were observed near the downstream slope (right side of the dam). The concrete spillway and training walls were in good condition. Some flow of water was observed passing below the spillway and flowing out the spillway channel. The spillway is not adequate to pass the 0.5 PMF test flood outflow without overtopping the dam. The test flood would overtop the dam by about 0.2 feet. The spillway pass about 46 percent of the test flood outflow without overtopping the dam.

The dam is roughly 430 ft. long consisting of a stone and concrete outlet structure abutment 53 ft. in length, a curved spillway 147 ft. long, and an 80 ft. long auxiliary spillway. The maximum height of the dam is about 27 ft. above the bed of the Quinnipiac River. The dam appears to be in fair condition. There are some areas requiring attention. Based upon the size and hazard classification, The Test Flood will be equivalent to the Proable Maximum Flood. (Author).