Norwich ― The Upper Falls Dam on the Yantic River has been falling into the river one granite block at a time for the past several years, and the city would like to hasten the process, starting with a study on the feasibility and flood-reduction benefits of removing all or part of the dam.

The City Council on Monday voted to accept a grant of $44,800 from the Federal Emergency Management Agency’s Building Resilient Infrastructure and Communities program to study the potential flood-prevention benefits of removing the 1860 dam. The city Public Works Department will provide the $14,000 city match for the grant with in-kind engineering services, Public Works Director Patrick McLaughlin said.

City officials have wanted to remove the dam for years to reduce potential flooding upstream in the Yantic River. The dam is not functional and is not a barrier to migrating fish swimming upriver, since the natural gorge at Yantic Falls, Uncas Leap has been a historic barrier to fish. State law requires dams that are barriers to fish migration to be removed or fitted with fish ladders.

State officials determined removing the dam would not significantly reduce flooding immediately upriver, where contractors now are working on a new Sherman Street Bridge. The new bridge will be 18 inches higher than the old bridge, allowing higher river levels during major storms.

But McLaughlin said he believes removing all or part of the dam would ease flooding, especially when considering climate change and the anticipation of more serious storms affecting the volatile the Yantic River.

“It would help lessen the flooding, a climate change countermeasure,” McLaughlin said, “because even with the Sherman Street Bridge being raised 18 inches, it is barely above the 100-year flood. It would give us better flood control.”

During heavy rains, the Yantic River frequently floods homes, businesses and streets in low-lying areas of Norwichtown and Yantic along Town, West Town and Sturtevant streets.

The granite dam, a key part of a thriving water-powered industrial district in the 1860s, has a complex design. The portion nearest to the accompanying powerhouse was built as a granite wall, the river water allowed to flow through a 3-by-3-foot square wooden gate at the base when controlled by hydropower operators.

The gate rotted away some 20 years ago, allowing the river to flow through the base of the dam when river levels are low. McLaughlin said a crew from Manafort Bros., the contractor building the new Sherman Street Bridge, recently cleared debris that had been clogged the gate opening at the base of the dam to improve flow.

The second half of the dam has an earthen slope built up behind the granite wall that forms a gentle slope from the river up to the top of the dam. In this area, portions of the granite dam beneath the cap stones also have washed away into the river.

McLaughlin said the study will determine whether all or just part of the dam could be removed.

He said the city would keep the granite blocks, perhaps using some to fill in the deep hole at the base of the dam where the rushing river has eroded the riverbed and using some to decorate the Upper Falls Heritage Park, where round millstones already have been positioned to line the cul-de-sac driveway.

“We’ll see what the study recommends,” McLaughlin said.

c.bessette@theday.com