Last week, in a fit of Spring cleaning, I unearthed a pile of National Park Service brochures displaced from bedroom walls now cluttered with maps of Alaska. One of them, an eye-catching portrait of a Pacific Northwest rainforest, bore the headline “Freeing the Elwha.”
When I collected that Olympic National Park brochure nearly three years ago, I didn’t even know ‘the Elwha’ was a river, much less that its two large dams were slated for removal beginning in late 2011. Now, it’s hoped that by summer’s end, the Washington State river will flow free for the first time in a century.
Over the last year and a half, the Elwha’s reverse transformation into an untamed river has caught the attention of fishermen (welcoming the return of the salmon migration once blocked by concrete), boaters (navigating a changeable rivercourse as decades of stored sediment are purged from the riverbed), hydrologists (excitedly measuring shifts in water flow rate and level), and conservation biologists (checking their predictions against the actual trajectory of ecosystem restoration).
And no wonder: The Elwha is the site of the largest dam removal project in United States history.
But it certainly won’t be the last. Now that we’ve dammed two thirds of the world’s rivers, we’re witnessing the large-scale environmental effects of these structures. Yes, they generate electricity, control flooding, and secure water supplies. But they also block the movement of aquatic creatures, especially migratory fish like salmon that swim upriver to breed. They intercept nutrient-laden sediment that previously replenished the floodplain below. They induce water-rights conflicts and diminish downstream water supply and quantity. And the lakes that form behind them displace plants and animals – including, sometimes, people – and can play host to harmful algal blooms.
Do the benefits outweigh these costs? When dams were novel and rare, the answer was usually “Yes.” But today, American infrastructure is reaching the age of reevaluation: The average age of our 84,000 dams is 52 years. 4,000 dams are already in need of repair, 2,000 of which would threaten human life if they failed. And it’s when we look at these dams that we’re increasingly deciding, “No. Dam removal is the best option.”
Just last week, the Department of the Interior recommended dismantling four dams in Northern California and Southern Oregon to free the Klamath River.
The decision was based heavily on the astronomical costs of retrofitting and re-permitting the structures, plus the restoration benefits to the salmon and steelhead fisheries, whose stocks have fallen to a fraction of historical levels. Dam removal should also help resolve the water rights conflicts that flood the region every dry year.
But that hasn’t stopped the dam removal negotiation from turning into a multi-year beaurocratic odyssey that teeters on the brink of collapse with every new wave of elected officials. If the dams are removed, it won’t be cheap. The Department of Interior estimates $290 million in costs, plus almost $1 billion in restoration efforts – like building bat habitat to replace the cavernous dam infrastructure. But it will theoretically be a better financial deal in the long run.
Of more concern to me, though, is the effect of taking the dams’ collective 163 MW of electricity generating capacity offline. The dams produce enough electricity to power 70,000 homes, and they do it using a renewable resource. Where will the replacement power come from?
While the government report doesn’t delve much deeper than the financial details (coal is the only cheaper alternative), it does note that, if dam-owner PacifiCorp holds to California’s 2020 standard of 33% generation from renewable resources, the dam removal will actually reduce the emission of greenhouse gases.
That’s because hydroelectric power isn’t always squeaky clean. In this case, by trapping sediments below relatively calm lake waters, the dams set up the ideal habitat for methane-emitting microbes. Methane is a potent greenhouse gas, so eliminating the dams, and the methane source locked behind them, could represent an important emissions reduction.
In any case, the optimistic calculation amounts to emissions reductions of only a few percent, which will hardly halt climate change in its tracks. So while dam removal makes good ecological sense at a local scale, I’m not keen on taking all our hydroelectric power offline.
What we have, then, is yet another battle between what we need to use, and what we can afford to protect – or, in this case, restore. Perhaps, as this generation of dams turns over into the next, we can use the last century’s lessons and technological innovations to sidestep some of this conflict. Then, it becomes a matter of deciding what we’re willing to do without. Power sockets or sockeye salmon? Ready irrigation or a wilderness paddle?
Holly welcomes reader questions, comments, and just about any dam thoughts at hollyvm “at” stanford “dot” edu.