Reconnecting Habitat Aids Migratory Fish on the Roanoke River

The Roanoke River is one of the largest and wildest rivers on the East Coast. It provides essential spawning habitat for migratory fish like striped bass, blueback herring, hickory shad, American eels, and the endangered Atlantic sturgeon. Although the river is mostly undeveloped, many old culverts at road-stream crossings and other small barriers disrupt its floodplain. These structures can block fish from reaching their spawning areas or trap them in standing water where low oxygen levels can kill them.

Now, with $3.2 million from NOAA's Office of Habitat Conservation , The Nature Conservancy is removing barriers along the lower Roanoke River in North Carolina.

This project will:

• Replace six undersized culverts with bridges and remove two additional barriers
• Open more than five miles of stream and 1,130 acres of floodplain forest
• Allow fish to move freely between the floodplain and the main river
• Improve water quality and reduce prolonged flooding to landowners

This work is part of a broader effort led by The Nature Conservancy to reconnect floodplains and help declining fish populations recover in the Roanoke watershed. Since 2019, NOAA has supported TNC's field assessments, landowner outreach, and barrier removal projects. The earlier work led to landowners requesting help on their own properties.

"NOAA's support allowed TNC to scale our restoration work to incredible levels that will really make a difference to the important aquatic species," said Julie DeMeester, director of water for TNC North Carolina. "At the end of the collective work, we expect to have opened more than 70 miles of stream and thousands of acres of floodplain forest."

A River System Worth Protecting

Stretching more than 400 miles from the Blue Ridge Mountains to Albemarle Sound, the Roanoke River hosts nine species of migratory fish. Many of these populations have declined over the past century, which makes the high-quality habitat on the lower Roanoke especially important.

"The Roanoke is one of the most impressive river systems in the country," said DeMeester. "Its extensive bottomland hardwood forests, five-mile-wide floodplains, and nursery habitat support rare species and one of the only naturally reproducing striped bass populations in the South."

Some of these fish species spawn on the river's floodplain, the area along the river that floods when water levels run high in the springtime. Recognizing this ecological value, TNC and its state and federal partners have protected more than 95,000 acres of land along the lower Roanoke.

Stream Barriers Kill Fish

The Roanoke River has large flows that spread out onto the adjacent floodplain and cause the water level to rise several feet. This connected system benefits fish like blueback herring, which lay their eggs among cypress trees' horizontal roots. Yet, in many places, old earthen berms and undersized culverts clogged with debris prevent water from draining. When water becomes trapped behind these structures, oxygen levels drop, leaving fish stranded in stagnant pools without enough oxygen to breathe.

"Water in the floodplain is supposed to rise and fall with the river," said NOAA Marine Habitat Resource Specialist Stephanie Krug. "When water gets stuck behind barriers, it stays on the landscape too long. That leads to water quality issues, fish kills, and other problems that ripple through the whole system."

TNC worked for decades with the U.S. Army Corps of Engineers and Dominion Energy to adjust water-release patterns at the three upper-river dams to create a more natural flow in the main Roanoke River channel. But with an estimated 1,400 potential road barriers across the watershed, flooding can still trap and kill fish. Research helped TNC determine which areas would benefit the most from barrier removals.

Removing Barriers Saves Fish

Earlier restoration projects on the lower Roanoke floodplain show that fish survive far better when barriers are removed.

In 2019, NOAA awarded funds to TNC to replace undersized culverts with bridges on TNC's Big Swash property. After major flooding in spring 2025, researchers compared the restored Big Swash site with Company Swamp, a future project site that still had undersized culverts in place.

The difference was striking:

• At Company Swamp, researchers counted 46 dead hickory shad in a 150-meter stretch upstream of the culvert
• At Big Swash, researchers found only one dead shad in the same distance

Oxygen levels at the restored site were six times higher than at the culvert site. The bridges allowed the floodplain to drain and prevented fish from becoming trapped.

Scientists partnering with TNC are also using environmental DNA (eDNA) and other tools to track how fish use streams before and after restoration. Early monitoring shows that blueback herring and other species gain access to miles of new habitat once culverts are replaced.

"We find that our target species cannot access the habitat before restoration," said DeMeester. "After restoration, they gain miles of tributaries and hundreds of acres of floodplain forest."

Benefits to People

Restored floodplains drain more quickly. As water spreads out and recedes naturally, the severity of flooding affecting landowners decreases. These improvements also increase water quality and support local hunting, fishing, and bird watching.

Each individual barrier removal is small, but together these projects create meaningful ecological gains. By reopening habitat, restoring natural flow patterns, and improving water quality, NOAA, TNC, and their partners are helping rebuild a better river system for fish and people.