Naugatuck Valley COG
The Naugatuck River near the Kinneytown Dam, in a Flickr photo posted in September.
ANSONIA – The Naugatuck Valley Council of Governments (NVCOG) will lower the water level in Coe Pond by about three feet over the next two weeks.
According to a press release sent out on Monday, construction workers will enlarge a notch in a concrete spillway at the Coe Pond Dam to lower the water.
The Coe Pond Dam is an embankment dam running along the length of the canal just downstream from the Kinneytown Dam. That canal feeds directly into Coe Pond.
Lowering the water level in the dam was recommended in an engineering report commissioned by NVCOG in March. The intent is to mitigate flood risks to the nearby Waterbury Branch commuter train line.
The lower Naugatuck Valley experienced some of its worst flooding in decades on Aug. 18. During those floods, washouts knocked that train line out of service. The largest of those washouts was just downstream from the Kinneytown Dam.
However, the Coe Pond Dam held up through the storms. Dam inspectors cleared both dams afterward and said no repairs were needed.
During a recent Q&A with Ansonia and Seymour residents, officials were asked about flood risks at the dams, given that they survived a 1,000-year flood event. Officials said the dams were lucky that the worst flooding was further upstream in Seymour and Oxford. They said that, had the rains been a few miles closer, the dams could have breached.
The lowering of Coe Pond is part of NVCOG’s project, in partnership with Save the Sound, to remove the Kinneytown Dam. The dam has not functioned in years. Fish can’t migrate upstream past the dam, and a fish ladder installed to aid in migration does not work.
It is unclear what will become of Coe Pond after the Kinneytown Dam removal project is completed.
NVCOG said in a 2022 grant application that it may fill in the pond with sediment currently logged behind the dam, but officials have since said that this is only one of several possibilities.
Other possibilities include letting the sediment flush downstream into the Long Island Sound, or removing it to licensed disposal facilities as necessary.
Sediment samples were recently collected and analyzed as part of the project. That testing will provide more information on pollution and contamination levels, which in turn will determine what’s ultimately done with the sediment. NVCOG said it will release those test results in the coming weeks.
The current work on Coe Pond is being done by Schumack Engineered Construction of Clinton. The map below – not-to-scale – roughly shows the location of the work, near N. Fourth Street in Ansonia. The diagram is taken from a September engineering report, and the image is a screenshot from Google Earth.
Google Earth / Karl F. Acimovic, P.E. & L.S.
A map attempting to show the location of the work. For clearer text, click the link to the September engineering report above.
