March 16, 2026, Construction Update

DCR and SumCo staff are aware that there was flooding at the Bel Air Dam site last week due to a release of water from Pontoosuc Lake.  Visual observations on Monday, March 16 indicate that the water level at the Bel Air site is decreasing, and we continue to monitor the river flows and water levels.  

As of Monday March 16, we have not observed any large sediment plumes discharging from Bel Air Dam, or substantial sediment in the water discharging through the cut in the dam. Two preparations were made in advance of construction activities that are now helping to manage water levels and reduce sediment movement:  1) an intentional cut in the Bel Air dam allows a controlled release of water, and 2) two turbidity curtains installed downstream of the dam are minimizing the transport of sediments and are being monitored and maintained as needed.     

As of Monday, March 16, the water level has decreased from the high levels observed last week. SumCo is currently setting up pumps in an attempt to maintain or lower the current water level in the Bel Air impoundment as rain progresses throughout Monday and Tuesday, March 16 and 17.  

Sediment excavation at the site has been underway since Summer 2025 and the majority of sediment has been excavated. Completion of sediment excavation is anticipated to be completed by mid-May 2026, or before.