The U.S. Army Corps of Engineers, New England District (USACE) is proposing to take action to alleviate the negative water quality conditions and address the increasing sediment accumulation in the flood storage area of the Northfield Brook Dam in Thomaston, Connecticut.
Pursuant to the provisions of the National Environmental Policy Act (NEPA) (Title 33, Part 230 of the Code of Federal Regulations) and Section 404 of the Clean Water Act of 1977 (P.L. 95-17), the U.S. Army Corps of Engineers conducted an environmental assessment (EA) of the potential environmental and socioeconomic effects associated with the operations and maintenance action, and is requesting public comment to determine if the proposed Federal action warrants the preparation of an environmental impact statement.
The preferred method is by converting the existing reservoir area from an eight acre artificially impounded lake to a dry-bed and allowing the facility to operate as a run of the river flood storage facility. The action would restore the original Northfield Brook channel behind the dam, create a riparian buffer zone, and create additional recreational lands. The facility would operate as a run-of-the-river facility during non-flood operations, and still function in its authorized capacity to protect downstream resources. The other method is to temporarily dewater the reservoir and remove sediment by mechanical means.
The expected results of the proposed action would have short-term impacts to aquatic habitats from temporary increases in suspended sediment loads into the water column as the water levels begin to reach the lower levels; and the eventual transport and deposition of sediment onto fisheries habitat that exist immediately downstream. The long-term impacts would be beneficial and result in re-establishing a naturally occurring flow regime that is closer to the original stream structure and restore the aquatic habitat to a natural riparian/riverine system after several decades of an artificial reservoir condition. Fisheries habitat would be enhanced over existing conditions. It would eliminate the permanent pool behind the dam which is an identified impaired waterbody. The action would result in direct beneficial impacts to river temperatures and dissolved oxygen levels in the Northfield Brook, and indirectly the Naugatuck River system. It facilitates a more natural sediment transport regime and restores habitat and downstream migration for fisheries, while allowing USACE to continue to provide flood storage capabilities and recreational opportunities.
Comments received by February 28, 2015 regarding the proposed Federal action will assist in USACE’s evaluation of the action and will be reflected in the project record.
- Updated: 3 February 2015