Of Oil Spills and Big Dams: What We Don't Know Can Hurt Us

06/02/2010 02:21 pm ET | Updated May 25, 2011

As BP's Gulf oil spill is so tragically demonstrating, once the cows are out of the barn and the oil is out of the well, it's too late to come up with a disaster response plan. We can't afford more BP disasters; it's time to start turning down projects with the greatest potential to create massive environmental catastrophes, and to decommission those that are ticking time bombs.

We now know that the BP oil rig was given a "fast pass" by government regulators. We know their plans for dealing with a deep-water blowout were completely inadequate. We will all be paying for this disaster for years to come.

Unhappily, oil rigs aren't the only potentially hazardous infrastructure we have to worry about. The world's rivers have been blocked off by some 50,000 large dams (and tens of thousands of smaller ones), and each one brings a unique brew of hazards. As with BP's Gulf spill, the owners of these dams are, generally speaking, remarkably unprepared to deal with the kinds of disasters that big dams can bring. Here's a roundup of the potential for disaster from big dams.

Seismic risk: Dams can induce earthquakes, by stressing and lubricating faults with millions of tons of water. Globally, there are over 100 identified cases of earthquakes that scientists believe were triggered by reservoirs (possibly including the 7.9 magnitude Sichuan earthquake in 2008). This phenomenon cannot be predicted, although building in known earthquake country increases the risks. Hundreds of new large dams are proposed or being built in some of the world's shakiest places: the Himalayas, China, Chilean Patagonia, Turkey, and Iran, to name just a few.

Dam Safety: "Dams are loaded weapons aimed down rivers, pointed at ourselves," writes Jacques Leslie in his 2005 book Deep Water: The Epic Struggle over Dams, Displaced People, and the Environment. As the world's dam stock ages (globally, 5,000 large dams are at least 50 years old), this problem grows - as does the issue of who is responsible for dam maintenance. In many cases where dams have become too costly to be maintained, owners have simply abandoned them. In the US, for example, about 15% of the nation's dams are of "indeterminate ownership"--meaning no one's minding the store. My organization calculates the global under-investment in dam safety at roughly $300 billion.

Climate risk: No dam today has taken into account the risk of climate change to its safety from super floods from unexpectedly large storms or melting glaciers upstream (a particular problem in mountainous areas - for example the Himalayas, where dozens of new dams are planned). Not to mention the risk to downstream residents of manmade drought, as their rivers dry up from upstream impoundments.

Damaged deltas: Dams could be setting us up for an epidemic of storm damage. Most of the world's major river deltas are sinking, thanks in large part to dams withholding land-building sediments, A shrinking delta was one factor in Hurricane Katrina, but there's much more destruction to come if we don't let rivers carry their muddy waters to the sea.

Destroyed fisheries: BP is destroying fisheries by spewing black death into the oceans. Dams damage fisheries by cutting off what fish need most: flowing water. Dams block migratory species from their breeding grounds, dry up downstream stretches of river, change rivers' chemistry and the timing of floods. Millions of people globally are at risk from dams' impact on their fisheries.

Decommissioning: Dams age, silt up, become obsolete. Yet no dam has ever included a funded plan for decommissioning; their owners build them as though they would live forever. What this means in practice is that affected communities have had to push for decommissioning, and sometimes even help fund it. In the US, activist communities working with local governments have succeeded in tearing down hundreds of obsolete dams, resulting in restored fisheries and natural habitat. But it should be the responsibility of dam builders and owners to plan and pay for a dam's decommissioning, not those who suffered losses from the dam.

When it comes to critical natural resources, we can't afford any more "hope and pray" risk management plans for projects that can cause widespread environmental and social catastrophes. It's time to just say no to the most dangerous projects whose destructive powers can't truly be mitigated, and to start demanding full risk disclosure and funded plans for dealing with risks on the rest.