Friday, May 5, 2023

Working to Open the Watershed

Chesapeake Bay Program, Over 31,000 miles of fish passage opened in the Chesapeake since 1988

For over 30 years, the Chesapeake Bay Program has been working to improve passage for migratory fish, whose migration corridors are blocked by hundreds of dams, bridges and outdated culverts built in the late 19th and early 20th century. By removing these barriers, our Fish Passage Workgroup supports not only striped bass, herring and shad, but also the American eel, that lives in freshwater rivers and spawn in the ocean, and the beloved brook trout, that migrates up and down freshwater tributaries.

The Bay Program has opened over 31,000 miles of stream habitat since 1988, and with each dam breach, culvert upgrade and fish ladder installation, we see fish species showing up in places they haven’t been for decades, if not centuries. In such a challenging time for the Bay’s health, this work gives us hope for the estuary’s wildlife.

Opening over 31,000 miles of fish passage

On a winter morning in 2004, deep-sea divers from the U.S. Army ventured into 32-degree water, hauling 50-pound hydraulic jack hammers to drill holes in the back of Embrey Dam on the Rappahannock River. The team was guided by both the U.S. Army Corps of Engineers and U.S. Air Force Reserves—a special training program called in to help detonate the dam and remove the obstruction from the tributary.

“We’re gonna blow this bad boy up come Monday morning,” said U.S. Army squad leader, Michael Poole, in a 2004 recording of the event.

Embrey Dam had been targeted by members of the Chesapeake Bay Program’s Fish Passage Workgroup as a key barrier to remove as early as 1988. The 22-foot-tall construction had outlived its usefulness for generating power and was no longer needed to supply drinking water in the nearby city of Fredericksburg, Virginia.

With the removal of the dam, migratory species found access to spawning grounds they hadn’t been able to reach for over 150 years.

“The hickory shad just poured through,” recalled Alan Weaver, fish passage coordinator with the Virginia Department of Wildlife Resources (DWR).

DWR is a key member of the Fish Passage Workgroup and has been surveying fish in the Rappahannock since Embrey was removed. According to Weaver, by 2008, American shad were found 28 miles upstream from where Embrey used to stand, at a survey location called Kelly’s Ford. In 2009, blueback herring were found in Kelly’s Ford as well as striped bass. And by 2016, the Smithsonian Environmental Research Center (SERC), another Workgroup member who conducts research on the Bay’s migratory fish, tracked blueback and alewife 62 miles from the ghost of Embrey Dam. “Bottom line is we know they’re using the habitat,” Weaver said.

The removal of Embrey Dam is one of several success stories for the Fish Passage Workgroup, which brings together state and federal agencies, nonprofits and academic institutions to identify dams that should be removed and determine how to do it.

“The biggest benefit of the Fish Passage Workgroup is that you have a variety of different agencies and organizations that can work together to figure out what priorities there are and then collectively pursue them,” said Jessie Thomas-Blate, dam removal expert with American Rivers.

A similar story can be found along the Patapsco River in Maryland. The removal of Bloede Dam is one of the most well-known in Maryland, but it was actually preceded by two others. The first to go was Union Dam up in the Patapsco headwaters, which was removed in 2010. Next was Simkins Dam, which was downstream of Union and went down in 2011. It took several years for the state of Maryland to take on the biggest and most expensive removal of them all, the Bloede Dam, which was finally removed using a controlled explosion in 2018. Just like in the Rappahannock, migratory fish are now passing more readily through the Patapsco.

“We've seen eight species upstream of Bloede Dam that were not observed pre-removal,” said William Harbold of Maryland Department of Natural Resources. “Alewife, blueback herring, gizzard shad, white perch, striped bass, yellow perch, quillback and northern snakehead.”

If it's working, why aren't the shad and herring runs in Maryland improving?


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