Highland Pond Dam is a 117 foot long stone rubble and earthfill dam which has a maximum height of 14 feet. There is a 21 foot long broad crested weir spillway located near the middle of the dam. The width of the embankment averages 20 feet including the dry stone masonry facing. The maximum storage capacity of the dam, with water at the top of dam, is 69 acre-feet. There are no known uses of the dam at the present time. The visual inspection of Highland Pond Dam indicated that the dam is in fair condition. The inspection revealed that the crest of the dam is covered with trees and rotted stumps. Trees were also noted growing at the downstream toe the dam. There is no riprap on the upstream slope, and erosion was noted in the vicinity of the left abutment. On the downstream face of the dam there was one area of bulging, along with an area of seepage, and a number of voids up to 6 inches wide between stones. The peak inflow at the dam is 1730 cfs which was calculated using the drainage area of 1.63 square miles and the Corps Peak Inflow Curve for rolling terrain. The peak outflow, after allowing for pond storage, is 1600 cfs. The spillway will discharge 175 cfs or 11% of the test flood with the pool level at the top of the dam. The test flood will overtop the dam by 3.2 feet.

The project, substantially reconstructed in 1967, has a total length of approximately 320 feet, consisting of an approximately 300 foot long embankment and a 20 foot long concrete spillway. The dam is approximately 23.5 feet in height above the streambed of Long Hill Brook and, with the pond level to the top of the dam, impounds approximately 250 acre-feet of water. The upstream slope is protected to the top of the dam by dumped rock riprap. The spillway is a concrete chute and is located near the right end of the dam. The low-level outlet facility is a 24 inch reinforced concrete pipe at the central portion of the embankment and is controlled from a concrete gatehouse on the dam. Based upon visual inspection and past performance, the project is judged to be in fair condition. No evidence of instability of the embankment or spillway was observed. However, there are items which require monitoring and/or maintenance, such as erosion of the spillway discharge channel and a stagnant water condition in the low-level outlet channel which does not allow a free flow of water from the toe drain pipes. Peak inflow to the reservoir at the 1/2 PMF is 850 cubic feet per second (cfs); peak outflow is 580 cfs with the lowest point along the top of the dam overtopped by 0.4 feet. The spillway capacity, with the reservoir level to the low point of the top of the dam, is 380 cfs, which is equivalent to 66% of the routed test flood outflow.

Upper Mill Pond Dam is a stone masonry dam approximately 100 feet long and 15 feet high. The spillway is 92 feet long, 9 feet wide and consists of a masonry broad crested weir. The water level is at the spillway crest and can be lowered by opening the low-level discharge gate which was recently made operable by the Middletown Water Department. In general, the overall condition of the dam is FAIR. The structural stability of the dam is good as evidenced by its vertical, horizontal and lateral alignment. The stone masonry is in good condition although moss and weeds are growing from the joints. The spillway weir and east abutment are in good condition. The west abutment is badly spalled at its base. The discharge gate inlet structure is badly spalled and the bar rack is cluttered with debris. There is some seepage at the east end of the dam where the stone masonry meets the abutment/ledge interface. Vegetation is growing around this area as well. The ledge continues along the downstream channel bank and there is minor seepage. A drainage pipe outlets above the west abutment. There is presently a scour hole at this location. This scour hole has caused the last section of the drainage pipe to collapse into the hole and is undermining the west spillway abutment. At the spillway elevation, the water surface area and storage capacity is 5 acres and 31 acre-feet respectively. The spillway capacity when the water level in the pond is at the top of the dam is 250 cfs. The test flood will overtop the dam by 1.8 feet.

The dam consists of a 400 foot long concrete spillway across the Farmington River with an adjacent hydroelectric generating powerhouse, and a 100 foot long butressed concrete transition dam spanning from the 70 foot long powerhouse to a 1050 foot long earth dike running along the pond shoreline. There are two low level sluices through the spillway section which are operated by hydraulic lifts in a chamber above the sluices. The sluices have an inlet elevation approximately 44.5 feet below the crest of the spillway. The 4 inlets to the turbines are approximately 34.5 feet below the crest of the spillway; the discharge flows to a tailrace channel cut into bedrock to the left of the spillway discharge channel. A fish ladder with an inlet about 1.5 feet below the spillway crest also discharges into the tailrace channel. All inlet gates are well maintained and operable. Based upon the visual inspection and past performance, the dam is judged to be in fair condition. No evidence of instability was observed in the dam or its appurtenances. The condition of the earth dike is good, however there are areas requiring attention. Based upon our hydraulics computations, the spillway capacity is 101,000 (cfs), which is equivalent to 51% of the routed Test Flood outflow.

This dam consists of an earth embankment, and a concrete wall which extends from the embankments to the spillway on each end of the spillway. The earth embankment is 500 feet long, 8 feet wide at the top and 6.7 feet high, with a downstream slope of 2H:1V. The concrete spillway is located at the western end of the dam and is 40 feet long with 15 inch high permanently attached timber flashboards. Based on the visual inspection, and past operational performance, the dam is judged to be in POOR condition. There are large trees growing on the embankment. The concrete wall is severely cracked and spalled and has been exposed on the downstream side by erosion. Seepage is occurring through the wall and all along the downstream toe of the embankment. The test flood for this dam is the 100 year flood. The test flood has an inflow equal to 1810 cfs and an outflow discharge equal to 1800 cfs at a stillwater elevation of 233.1 which will overtop the dam by 1.0 foot. The maximum outflow capacity of the spillway with the water level at the top of the dam is 53 cfs, which is 3 percent of the test flood outflow.

Crystal lake is an earthen embankment dam with a maximum height of 50 feet and a length of 130 feet. The upstream and downstream slopes are faced with riprap. The dam has a water control structure with a 36-inch diameter outlet pipe controlled by two sluice gates and a stop log spillway. The dam impounds Crystal lake which is used for recreational purposes. The lake has a storage volume of 350 acre-feet. Based upon the height of the dam, the size classification is intermediate. The dam is judged to be in generally fair condition. The crest is level, and no lateral movement was observed. The vertical and horizontal alignment of the dam is good. Some minor erosion along the dam adjacent to the left abutment was noted. The riprap paving on the upstream face is in good condition. The rockfill downstream face is also in good condition. Small trees and scrub brush are growing on the upstream and downstream slopes and could cause problems if not removed. The total capacity of the water control structure and the 36-inch diameter outlet pipe is adequate to pass the spillway test flood with a freeboard of 0.8 feet.