Dam Removal Helps Eels in Shenandoah

Removal of Embrey Dam lets more eels up the river

The removal of a large dam in Virginia has meant good news for the American eel population, according to a new study by the U.S. Geological Survey, U.S. Fish and Wildlife Service and National Park Service.

The research, published this month in Transactions of the American Fisheries Society, shows that the removal of Embrey Dam on the Rappahannock River increased American eel numbers in headwater streams nearly 100 miles away.

American eels migrate from their spawning grounds in the Atlantic Ocean to freshwater streams along the coast. Dams were thought to slow or even stop the migration.

Researchers studied eel populations in in Shenandoah National Park streams before and after the removal of the large dam in 2004. The study shows significant eel numbers beginning two years after the dam removal and nearly every year since.

"Our study shows that the benefits of dam removal can extend far upstream," said Nathaniel Hitt, a USGS biologist and lead author of the study. "American eels have been in decline for decades and so we're delighted to see them begin to return in abundance to their native streams."

Eels are a relatively rare catadromous fish; spawning in the deep ocean, and moving in to fresh water in both North America and Europe to grow to become adults.  So, unlike many fish, dams don't prevent them from reaching their spawning grounds so much as substantially restrict the range for them to grow in.

When I first moved to Maryland, eels were relatively common; you would often catch them on hook and line when fishing for bottom fish, and the Bay supported a substantial eel pot fishery (while not favorite food in the US, they are prized abroad).  Smaller one were commonly used as bait for large Stripped Bass (and still are, sometimes).  It's been many years since I have had to take one of the things off a hook; always a joy.

The Great Flush

China's giant man-made waterfall as floodgates are opened to send millions of tons of silt downstream

It is an scene of almost apocalyptic proportions. Bystanders are dwarfed as they stand watching a tremendous rush of water gushing through gaps in a dam in China, part of a carefully-choreographed operation to remove silt from the Yellow River in Luoyang, in the Henan province.

This annual operation sees more than 30 million tonnes of silt sent downstream a year, with more than 390 million tonnes shifted this way over the last 13 years. The silt-carrying water gushes out of three specialised holes in the dam of the Xiaolangdi Reservoir on the Yellow River during the annual silt-washing operation.

The Yellow River authority says such operations lowers the river bed in the lower reach of the river by an average of 2.03 meters each year.

The dam stands at 154m (505ft) tall and is 1,317m (4,321ft) wide. When it was built opened in 2000, following a six-year construction, it had cost US$3.5billion to construct.

The dam also produces almost 1.8 gigawatts of power, approximately the equivalent of nearby (to me) Calvert Cliffs Nuclear Power Plant (1.7 gigawatts). While it does have to be refueled annually, at least you don't have to flush 400 millions tons of silt out of it.

The Colorado River at Glen Canyon Dam (Hoover Lake) also benefits from a similar flushing program.  Instituted back in 2008, after years of regulated flows had allowed the river to silt heavily,  it was only partially successful in restoring a more natural river regime downstream. 

Maybe doing this with Susquehanna at Conowingo Dam could restore the Upper Bay to level required to support Atlantic Sturgeon reproduction, thought to be inhibited by the sedimentation.

Dam Removal on Patapsco River Being Planned

State considers removing Patapsco River dam

Fish making the spring spawning run from the Chesapeake Bay upstream into the Patapsco River swim about 11 miles of cool, shallow, flowing water before hitting a concrete wall nearly three stories high: the Bloede Dam. The wildlife obstacle and human safety hazard has stood for more than a century in Patapsco Valley State Park, but its days could be numbered.

The Maryland Department of Natural Resources is continuing a years-long effort to clear the Patapsco of dams that have outlived their original industrial uses and now turns its attention to Bloede. The dam is the largest of the Patapsco dams, and the most significant in terms of both wildlife and historical value.

"This one is the most important," said Jim Thompson, a DNR fisheries biologist, of the dam that straddles the Baltimore and Howard County line, 230 feet across and nearly 30 feet tall along the spillway. Because the Bloede Dam is the first obstacle that herring, shad and American eels hit as they head upriver, wildlife would benefit greatly if it were removed, he said.
...
A consultant's report prepared for American Rivers and released last week said up to 90 blueback herring and hickory shad were found in 15 minutes of sampling just below the dam in the spring of 2011. Above the dam, "none of these migratory species have yet been collected," the reports said,

American Rivers is devoted to restoring waterways across the country. McClain points to success stories in Maine, where she said dam removals in the past decade have helped to restore the herring population in the Kennebec River and bring back a commercial fishery.
....
The dam was built in 1906 to generate electricity for Victor G. Bloede's Patapsco Electric and Manufacturing Co., according to a historical documentation prepared by a consultant last year for the Maryland Historical Trust. It provided electricity for a 57-lot community called Eden Terrace being developed by Bloede, a German immigrant who moved to Baltimore in 1877 to establish a textile company.

The dam has served it's purpose, and now needs to be removed.  It was a marvel of progress when it was built, the first hydroelectric dam with the generating equipment built into the dam, but it is no longer needed or working, and is just preventing the movements of migrating fish.

Blow it.

While googling around on this story, I found this video of teens jumping into the Patapsco River up at Ilchester.



If I'm reading the map correctly, this is just upstream from the dam.