Dam Removal Restores Fish Passage to Mattatuxet River

By ecoRI News staff

The dam at Shady Lea Mill will soon be gone. (STB)

The dam at Shady Lea Mill will soon be gone. (STB)

NORTH KINGSTOWN, R.I. — Work began July 2 on the second phase of a $290,000 project to remove the designated “high-hazard” dam at the Shady Lea Mill and restore the natural free-flowing river channel.

The two-week project will improve passage for migratory fish and improve public safety, according to Save The Bay, one of the project partners. The initiative was made possible through a U.S. Fish & Wildlife Service program that helps private dam owners mitigate the risk of hazardous dams.

About 1.5 miles upstream of the fish ladder on the dam at the Gilbert Stuart Birthplace on Carrs Pond, the Shady Lea Mill dam is on the Mattatuxet River, a tributary of the tidally influenced Narrow River estuary, which flows into Narragansett Bay. All together, the river system hosts one of the largest herring runs in Rhode Island and supports many resident fish and wildlife species.

Save The Bay said the project will restore stream habitat and access to spawning areas for migratory fish in the uppermost parts of the Mattatuxet River, make this stretch of river more resilient to increasing storm events, and increase the quality of recreational fishing in the surrounding areas.

The stone and concrete dam was built in the 1820s to power what was then known as the Springdale Factory, a textile manufacturer, in the historic hamlet of Shady Lea. Like most of Rhode Island’s Industrial Revolution-era dams, it no longer serves a purpose, and has degraded so much that it was designated as a high-hazard dam by the Rhode Island Department of Environmental Management (DEM) after the March 2010 floods.

In addition to its ecological, recreational, and safety benefits, removal of the dam will reduce liability concerns for the dam’s private owner, Riesert Realty.

“This is a tremendous example of how private property owners and natural resource managers can work together to simultaneously benefit the dam owner, community, and natural resources,” said Kate McPherson, riverkeeper at Save The Bay.

Last fall, a small section of the dam was notched so that the impounded water above the dam could partially drain. Since then, the newly exposed shoreline has stabilized and re-vegetated with a wetland plant community. In this second phase of the removal project, the remainder of the dam at Shady Lea will be removed, and a stepped series of stone weirs will be installed to allow river herring and other fish to migrate upstream, even during low stream flow.

The project will preserve historic elements of the old mill raceway and a hydro turbine that exists next to the dam. Save The Bay and the DEM Division of Fish and Wildlife will continue to monitor fish passage and pool depth and flow conditions in the stone weirs.

“Once Shady Lea dam is gone, river herring will be able to pass upstream to their historical spawning grounds, and the risks of downstream flooding in the event of a breach will be reduced,” U.S. Fish & Wildlife Service Northeast regional director Wendi Weber said. “In time, the former upstream impoundment will return to streamside habitat, and sediment will again be carried downstream to nourish coastal beaches.”