Conowingo Dam: where clean energy is not just for the birds.

It’s rare that a major effort in environmental engineering, no matter how noble the intent or how solicitous the conception, yields absolutely no negative environmental consequences.  It’s probably more than rare.  I’d wager that such a feat has never occurred.  It’s all the more unsettling when one considers such vast civil undertakings as the canal system of the 19th century or the construction of flood protecting levees in the first half of the 20th.  These efforts unequivocally improved riverine transportation or burgeoning cities that depended on their proximity to waterways for commerce.  But they also permanently altered the size and reach of historic watersheds, in some cases forcing the depositing of sediment in new, unnatural, illogical locations.  The rapidly depleting Louisiana coastline, for example, owes a considerable amount to the forced channelization of the Mississippi River and the Atchafalaya Basin, dumping upstream settlement directly into the Gulf of Mexico—sediment that previously helped replenish the low-lying coastal areas south of Lafayette and Baton Rouge with the hydric soils that distinguished land from water (in a region where those lines of distinction are fuzzier than elsewhere).

At this point it’s even reasonable to question the prudence in “draining the swamp”, which was a pastime long before it ever became a political apothegm.  As recently as the 1950s, even many ecologists perceived swamps as foul and pestilential, an impediment to modern settlement of little environmental merit.  The term “wetland” only emerged in recent decades because “swamp” had almost devolved into a pejorative.  Now, a major undertaking in sustainable best practices (at least in the United States) is the restoration of wetlands, attributed to the accrued appreciation for their biodiversity and their contribution to natural flood management systems.  But we’ve become so enamored with wetlands that we even seek to introduce imitative variants—rain gardens or intermittent wetlands—as a natural feature within highly urbanized residential developments.  Will we rue these efforts fifty years from now?  Obviously I can’t answer that question, but I suspect we will find another fashionable earth-moving initiative long before then.

Taking these shifts in prevailing opinion into consideration, no one should be surprised that some of the major infrastructural initiatives of the last century have offered dubious environmental benefits.  Take this hydroelectric dam in eastern Maryland:

This leviathan spans the Susquehanna River about six miles upstream from its mouth at the Chesapeake Bay.  The Conowingo Dam, constructed in 1928, serves multiple purposes: it’s a major source of hydroelectric power for the region (exurbs of Baltimore), it’s a lake for recreational boating (the Conowingo Reservoir created by the dam), it’s the bridge for US Route 1, conveying thousands of vehicles across the Susquehanna River, it’s the site of Conowingo Fisherman’s Park, it’s the trailhead for the Lower Susquehanna Heritage Greenway Trail (which leads to the significantly larger Susquehanna State Park), and it’s one of the greatest locations on the East Coast for viewing the national bird.

Everyone one of these features to the Conowingo Dam is completely intentional.  Except that last one.

At the time of its construction, the Conowingo Dam was the second largest hydroelectric enterprise in the country, behind only Niagara Falls, and to this day it is one of the largest of such projects funded exclusively privately.  Without admittedly having researched the laws, I have a sneaking suspicion that a similar hydroelectric initiative funded by a utility such as Philadelphia Electric Company (as was the case here) would be impossible today due to regulations.  Nonetheless, the Conowingo Dam, currently operated by Exelon Corporation, continues to provide considerable power to the Philadelphia metro—having such out-of-state beneficiaries only compounds the political challenge—but it naturally also impedes the downstream flow of water, as it should.  It also impedes the migratory paths of fish, both upstream (seeking to spawn), or those getting trapped, killed, or stunned as they get sucked in and churned out by the turbines near the dam’s ten generators.  

Ultimately the downstream spot just south of the Conowingo Dam becomes a feast for herons, gulls, cormorants, and bald eagles; among the upstream-bound fish, American shad are the favored.  Because this man-made impediment could seriously compromise shad populations, the utility companies that manage Conowingo and two other nearby dams began trapping and rescuing programs approximately forty years ago, culminating in fully automated fish lifts installed in the late 1990s. Though successful at rescuing sizable numbers of American shad, a number still remain trapped in the dead end created by the dam, leaving them easy prey.  Thus, the birds routinely congregate near the dam; the black specks on the lefthand side of Rowland Island in the middle of the Susquehanna River in the photo below, are, in fact, a dense convocations of bald eagles.

But you don’t need binoculars to appreciate them.  They’re perched in the trees right above the greenway trail.

The sharpest pic here is courtesy of Sarah McAfee:

And yes, it’s easy to spot them in flight as well.

(One important learning experience from being around this many eagles—more than I’ve ever encountered in total all the rest of my life—is you learn that the searing cry we have long associated with eagles is, in fact, a total myth popularized by TV commercials. Those are canned sounds.  The actual cry of a bald eagle isn’t intimidating in the least.  Frankly, it sounds like that errant squeaky fourth wheel on a grocery cart.) 

Conowingo Fisherman’s Park is indeed popular with flightless, featherless, two-legged creatures who enjoy fishing.  But I’d imagine that two-thirds of the cars parked in the lot are here for the bald eagles.

Here at Conowingo we encounter the unintentional consequences of a century-old source of “green energy”; I have a sneaking suspicion such a term didn’t exist back then, nor was there quite the full awareness of the consequences that environmentalists have witnessed in the ensuing years, positive and negative…simultaneously.  The trapped American shad creates a condition that almost ensures their failure to thrive, while at the same time amplifying their vulnerability to predators.  But the predator in this case is the bald eagle, a specie that less than fifty years ago was endangered and remained on the threatened list until 2007.  The cultural value of a charismatic bird like the bald eagle, the feathered synecdoche for America, was and still is so great that the possibility of introducing a captive food source, combined with a chance for the public to appreciate the mighty raptor, superseded the interest in saving the American shad, a specie of “least concern”.  The sightseeing opportunities only help to confer greater value not just to the park, or the predatory birds, but also to the networked food chain in this contrived habitat.  It’s not the first example I’ve recalled of energy extraction as a tourist attraction.  If only there were signage to inform people of what I researched, then they could both learn about and appreciate the mechanics of a “fish lift”.

Instead, the closest we get to a sign in this popular but not fully thought-out fishing-spot-turned-park is this one:

And that’s because, at Conowingo Fisherman’s Park, the bald eagle may remain the biggest attraction, but the most up-close-and-personal avian encounter is likely to be this one:

Turkey vultures are everywhere, they’re unafraid of humans, and they prefer the ground, although the (difficult to see) vulture perched atop the streetlight was so perfectly positioned, its vast wings outstretched at one point, that it looked like a decoration.

The warning is justified.  On a quiet day with fewer people present (the eagles are most prevalent in the winter and early spring), the vultures can gather around a parked car and pull at any available rubber: lining the door, the windshield wipers, maybe even parts of the tires.  They eat and then regurgitate it, causing hundreds of dollars of damage.  Exelon provides and maintains parking, lighting, and signage.  But they aren’t liable for the damage from these sinister lurkers, the grim reapers of the animal kingdom and an impressive sight all their own.  It’s an unusual pairing at the Conowingo Dam: the most widely embraced symbols of patriotism juxtaposed with the most famous scavenger.  Maybe in the long run, it’s best just to stick with the fish.  They’re not gong anywhere.